nanoPT2013 abstract book

Index

Foreword Page 1

Organisers/Sponsors/Committees Page 2

Exhibitors Page 3

Speakers Page 9

Abstracts Page 19

Posters List Page 103

n a n o P T 2 0 1 3 P o r t o ( P o r t u g a l ) | 1

Foreword

We take great pleasure in welcoming you to Porto (Portugal) for the 1st edition of the nanoPT

International Conference (nanoPT2013).

This first edition is organized with the purpose of strengthen ties nationally and internationally on

Nanotechnology and, pretends to be a reference in Portugal in the upcoming years. This conference will

encourage industry and universities working on the Nanotechnology field to know each other and to

present their research, allowing new collaborations between nearby countries such as Spain and France.

NanoPT will be held every year in Portugal and will let the participants presenting a broad range of current

research in Nanoscience and Nanotechnology, not only the most prominent investigations/studies in

Portugal but from all over the world.

We are indebted to the following Scientific Institutions, Companies and Government Agencies for their

financial support: nanoVALOR, Viajes El Corte Inglés, International Iberian Nanotechnology Laboratory

(INL), American Elements, ICEX, FEI and Centre for Nanotechnology and Smart Materials (CeNTI).

We would also like to thank the following companies and institutions for their participation: nanoVALOR,

Iberlaser, Paralab, Irida, Dias de Sousa, ICEX, SPECS, ScienTec Ibérica and NanoSight.

In addition, thanks must be given to the staff of all the organising institutions whose hard work has helped

planning this conference.

Organisers

In partnership with:


Sponsors

Committees

O r g a n i z i n g C o m m i t t e e

Antonio Correia Phantoms Foundation (Spain)

Braz Costa CITEVE/CENTI (Portugal)

Luis Melo Instituto Superior Técnico (Portugal)

Antonio Correia Phantoms Foundation (Spain)

Jose Rivas INL (Portugal)

Vasco Teixeira Univ. Minho (Portugal)

T e c h n i c a l C o m m i t t e e

Viviana Estêvão Phantoms Foundation (Spain)


Exhib itors

4 | n a n o P T 2 0 1 3 P o r t o ( P o r t u g a l )

n a n o V A L O R

Nanotechnology is the common denominator that gathers eight institutions, from the euro-

region Galicia-Northern Portugal, around Nanovalor, a project funded by the ERDF through the

Programa Operativo de Cooperación Transfronteiriza España-Portugal 2007-2013 (POCTEP). The

NanoValor Project's mission is the consolidation of institutional links between key actors in the

field of Nanotechnology in the North of Portugal-Galicia Euroregion through the creation of a

Competitiveness Pole (PCT) sustained by collaborative models based on R&D and innovation

communities.

The NanoValor Project consortia is composed by 8 partners: Universidade do Minho

(coordinator), TecMinho, International Iberian Nanotechnology Laboratory (INL), Universidade do

Porto, INESC-Porto from Northern Portugal and Universidad de Santiago de Compostela (USC),

Fundación Empresa-Universidade Galega (FEUGA) and Asociación de Investigación Metalúrgica

do Noroeste (AIMEN).

www.nanovalor.org


I b e r l a s e r

Iberlaser was setup in 1993, and is based in Madrid-Spain. Our principal mission statement is

provide research Spanish market with the novel instrumentation and highly qualified servicing.

Our lines of products include Bio-technology, Laser Technology, Low light Imaging, Photovoltaics,

Spectroscopy, Surface chemistry, Vibrate Control.

Tel: 91 658 67 60

Fax: 91 654 17 00

www.iberlaser.es

[email protected]

P A R A L A B

PARALAB was founded in 1992 by a group of young entrepreneurs. The objective was to establish

a new company on the field of distribution of scientific instrumentation, whose excellence of the

proposed technical solutions, the strong commitment for superior after sales support and

customer training, would differentiate it from all competitors. Since then, PARALAB became a

reference in the Portuguese market for:

− distribution of analytical instrumentation for laboratory and process applications

− system integration of solutions for laboratory and process applications

PARALAB has all the resources to maintain the level of support that its customer´s growing

expectations currently demand. PARALAB´s Commercial Area has four divisions:

− Analytical equipment

− General Laboratory Equipment

− Process and environmental Equipment

− Industrial Equipment

Tel: +351 224664320

Fax: +351 224664321

www.paralab.pt

[email protected]


I r i d a

Irida Iberica is one of the youngest but most dynamic nanotechnology instruments providers in

Spain. We introduce novel techniques and the best technological solutions for most of the

nanotechnology applications challenges. Irida offers a unique value to price combination for a

wide variety of surface analysis products like Optical Profilers or Atomic Force Microscopes, as

well as the most versatile configurations for material science and biological samples analysis. Our

products, manufactured by world leading companies, are some of the most sophisticated

instruments in the market because of their cutting edge technology. But it is our service

department that makes the difference because is what gives our clients the security of a nonstop

research or production work.

Irida Iberica S.L.

Diligencia 9

28108 Madrid, Spain

Tel: +34911130824

[email protected]

www.irida.es

D i a s d e S o u s a

A Dias de Sousa, Instrumentação Analítica e Científica SA (DS, SA), a leader in the Portuguese

Market for both General Lab Equipment and High Technology Solutions and Services, where

Nanotechnology represents an area where we are pioneers in Portugal. DS, SA works together

with world reference Partners, like Bruker AXS, Bruker MicroCT, Bruker Nano, LUM, Kruss,

Thermo MC, Ametek, and many others, enabling us to provide high end solutions in the

Nanotechnology and NanoScience fields. Dias de Sousa, SA (www.dias-de-sousa.pt/sa), a matter

of trust since 1983, enabling Science to go forward!

Dias de Sousa.

Paula Lourenço Cid

Diretora Comercial

Tel: +351 916 604 868

[email protected]

www.dias-de-sousa.pt/sa


S P E C S

SPECS Surface Nano Analysis GmbH as a leading manufacturer produces innovative components

and customized systems for surface spectroscopy and microscopy. The customized systems are

highly integrated with facilities for sample and thin film preparation and in-situ analysis from UHV

to high pressures. Main analysis components are the hemispherical energy analyzer family

PHOIBOS, the time-of-flight spectrometer THEMIS, the ultimate stability Aarhus SPM family, the

ultimate low temperature SPM family JT-SPM, the Tyto SPM head, the KolibriSensor, the in situ

SPM Curlew and the high resolution LEEM/PEEM instrument.

Principal Office

SPECS Surface Nano Analysis GmbH

Voltastraße 5

D-13355 Berlin

Germany

Tel: (+)49 - 30 46 78 240

Fax: (+)49 - 30 46 42 083

[email protected]

www.specs.com

T h e S p a n i s h I n s t i t u t e f o r F o r e i g n T r a d e ( I C E X )

The Spanish Institute for Foreign Trade (ICEX) ("Instituto Español de Comercio Exterior") is the

Spanish Government agency serving Spanish companies to promote their exports and facilitate

their international expansion, assisted by the network of Spanish Embassy´s Economic and

Commercial Offices and, within Spain, by the Regional and Territorial Offices. It is part of the

Spanish Ministry of Industry, Tourism and Trade ("Ministerio de Industria, Turismo y Comercio").

Espa&ntildea, Technology for life:

www.spainbussiness.com


S c i e n T e c I b e r i c a

ScienTec Ibérica company is specialized in distribution of scientific equipment dedicated to R & D

laboratories and industry. Its fields of activity related to the atomic force microscopy,

profilometry, interferometry and the nanoindentation.Serving the research and industry for over

10 years, ScienTec Ibérica accompanies you in your various projects by offering systems adapted

to your application (nanotechnology, polymer, material, biology, semiconductor...).

ScienTec Iberica

C/ Rufino Sánchez 83

Las Rozas - Madrid 28290

Tel: +34 91 842 9467

[email protected]

www.scientec.es

N a n o S i g h t

NanoSight’s “Nanoparticle Tracking Analysis” (NTA) detects and visualises nanoparticles in liquids

down to 10nm, material dependant. It measures size, size distribution, concentration, zeta

potential and fluorescence, on a particle-by-particle basis. This technology is being utilised in the

development of drug delivery systems and viral vaccines, and in nanotoxicology. It also gives

insight into the kinetics of protein aggregation and has a growing role in biodiagnostics, including

the detection and speciation of exosomes and microvesicles. NanoSight has installed 550+

systems worldwide and its technology is validated by 600+ third party papers citing NanoSight

results, consolidating NanoSight’s leading position in nanoparticle characterisation.

www.nanosight.com

Speakers


Index alphabetical order

K: Keynote Speakers

O: Orals (Plenary Session)

OP: Orals (Parallel Session)

Speakers

Page

Aguilar Ribeiro, Helena (University of Porto, Portugal)

"In situ decoration of gold nanoparticles on TiO2/cellulose nanocomposites: An application

toward dye-sensitized solar cells on paper substrates" O 21

Ahn, Kang-Hun (Chungnam National University, Korea)

"Anomalously strong confinement in strained graphene systems" O 23

Arias Otero, Jorge (Centro de Aplicaciones Laser-AIMEN, Spain)

"To be defined" O -

Braun, Hans-Georg (Leibniz Institute of Polymer Research, Germany)

"Complex structure formation in ultrathin films and at liquid/gas interfaces" O 24

Calado, João (Innovnano, Portugal)

“High Pressure Physics on large scale Synthesis of Nanomaterials” K 25

Carneiro, Joaquim (University of Minho, Portugal)

"Development of Anodic Aluminum Oxide (AAO) membranes for cell culture substrates" OP 26

Chachamidou, Maria (Aristotle University of Thessaloniki, Greece)

"Commercialisation of Organic and Large Area Electronics – COLAE Project"

O 27

Charra, Fabrice (CEA, France)

“Direct imaging of optical field enhancement, propagation and antenna effects for

molecular plasmonics” K 28

Correa-Duarte, Miguel Angel (Universidade de Vigo, Spain)

"Inorganic Complex Nanocapsules: Synthesis and Applications" O 29

Costa, Claudia (Ynvisible S.A., Portugal)

"PEDOT and graphene based electrodes printed by screen-printing on plastic and paper

and application on flexible electrochromic devices" OP 30

Cuniberti , Gianaurelio (Dresden University. of Technology, Germany)

“Biosensing with Silicon Nanowire FETs: From Theory to experiments” K 31

De la Prida, Víctor (Universidad de Oviedo, Spain)

"Electroplating of Co54Ni46/Co85Ni15 multilayer nanowires from single electrochemical

bath in anodic alumina templates" O 32

dos Santos, Tiago (Instituto de Engenharia Biomédica, Portugal)

"Uptake of Polymer-Based nanoparticles of different size into multiple cell lines:

approaches to control and understand bio-nano interactions" O 34

Evangelista, Marta B. (BIOCANT, Portugal)

"Antimicrobial peptide permanently immobilized on surfaces with high activity in the

presence of serum and low cytotoxicity against human cells " OP 35

Fernández Rossier, Joaquín (INL, Portugal)

“Spin Physics in two dimensional materials: from graphene to MoS2 “ K 36

Fonseca, Joana (CeNTI-Centre for Nanotechnology and Smart Materials, Portugal)

"Printed sensors: from the printing process to the data acquisition system design" O 37

Fraga, Sonia (REQUIMTE, Portugal)

"Biokinetics and toxicity of gold nanoparticles after single intravenous injection in the rat" O 38


Page

Franco, Ricardo (REQUIMTE-Universidade Nova de Lisboa, Portugal)

"Bionanotechnology for Malaria Diagnostics: Towards a Point-Of-Need Assay" O 40

Freitas, Paulo (INL, Portugal)

“Spintronic devices for biomedical applications” K 42

Gaspar, Rogério (Univ. of Lisbon, Portugal)

“Nanomedicines: the clinical use and the challenges coming from new manufacturing

science and healthcare costs” K 43

Glückstad, Jesper (Technical University of Denmark, Denmark)

"Structure-mediated nanoscopy" O 44

Gnauck, Peter (Carl Zeiss, Germany)

"Helium Ion Microscopy. Extending the frontiers of nanotechnology"

O 46

Gomes, João (ISEL-Instituto Superior de Engenharia de Lisboa, Portugal)

"Assessment of nanoparticles emissions resulting from arc welding of mild steel" OP 48

González Salazar, Jhon Wilfer (INL-International Iberian Nanotech. Lab.,Portugal)

"Graphene single electron transistor as a sensor for magnetic molecules"

O 50

Hueso, Luis (CIC nanoGUNE, Spain)

“Spintronic devices with fullerenes” K 51

Kasumov, Alekber (Universite Paris-Sud, France)

"Long range electronic tranport in DNA molecules"

O 52

Korgel, Brian (Univ.of Texas at Austin/Depart. of Chemical Engineering, USA)

"Silicon and Germanium Nanowires for Next Generation High Capacity Lithium Ion Batteries"

O 54

Landman, Uzi (Georgia Inst. of Technology, USA)

"To be defined" K -

Larkin, Ivan (University of Minho, Portugal)

"Edge magnetoplasmons in strongly non-uniform magnetic field"

O 55

Marques, António (CeNTI-Center for Nanotechnology and Smart Materials, Portugal)

"Transparent thin films for TCOs replacement–A Roll-to-Roll approach" OP 56

Medforth, Craig (REQUIMTE-Universidade do Porto, Portugal)

"New Insights into the Synthesis and Structures of Self-Assembled Porphyrin Nanomaterials"

O 57

Melle-Franco, Manuel (University of Minho, Portugal)

"Realistic modeling of carbon nanostructures, bridging the gap between theory and experiment" OP 59

Moreira, João Nuno (University of Coimbra, Portugal)

"Tailoring Nanomedicines aiming at anticancer molecular therapy"

O 60

Moura, Vera (Treat U, Lda, Portugal)

"PEGASEMP - impact on the treatment of solid tumors with a novel microenvironment targeting" OP 62

Paiva, Maria da Conceiçao (Universidade do Minho, Portugal)

"The influence of carbon nanotube functionalization on the dispersion in polypropylene

by melt blending" OP 64

Pereira, Clara (REQUIMTE-Universidade do Porto, Portugal)

"Engineered Nanomaterials for the Development of Functional Textiles: From Concept to

Technological Applications" OP 66

Pereira, Eulalia (Universidade do Porto, Portugal)

"Nanobioconjugates of tyrosinase and laccase with gold nanoparticles: effect of

coupling method and capping agent on enzymatic activity"

O 68

Peres, Nuno (Univ. Minho, Portugal)

“Exact solution for square-wave grating covered with graphene: Surface plasmons-polaritons

in the THz range” K 70

Pérez-Prieto, Julia (Universitat Valencia, Instituto de Ciencia Molecular (ICMol), Spain)

"Symbiosis between nanoparticles and their organic ligands"

O 71


Page

Piedade, Ana Paul (CEMUC-GNM, Portugal)

"Sputtering and nanosurface modification of biomedical devices" OP 72

Rai, Akhilesh (Universidade de Coimbra, Portugal)

"Design of potent antimicrobial and biocompatible gold nanoparticles"

O 74

Rana, Sohel (University of Minho, Portugal)

"Development and characterization of carbon nanotube dispersed carbon/phenolic

multi-scale composites"

O 75

Rauls, Eva (University of Paderborn, Germany)

"Formation of thin organic layers at the example of Co-and Cu-Phthalocyanines on Au-

substrates-a theoretical investigation"

O 77

Rocha, Nuno (University of Coimbra , Portugal)

"Development of polymer-based self-assembly systems for advanced applications"

O 79

Roche, Stephan (CIN2-ICN-CSIC, Spain)

“Quantum Transport in Disordered Graphene : Scaling Properties and Spin relaxation

Mechanisms” K 81

Sáenz, Juan José (Univ. Autónoma de Madrid, Spain)

“Scattering Asymmetry and Non-conservative Optical Forces on Nanoparticles” K 82

Sáez Puche, Regino (Universidad Complutense Madrid , Spain)

"Synthesis, characterization and magnetic properties of ZnFe2O4 spinel nanoparticles

encased in porous matrices"

O 83

Salgueiriño, Verónica (Universidade de Vigo, Spain)

"Hybrid Nanostructures assembling Antiferro- and Ferrimagnetic Oxides" OP 85

Samitier, Josep (IBEC, Spain)

Functional liposome arrays based on natural nanovesicles” K 86

Schmool, David (IFIMUP-IN, Universidade do Porto, Portugal)

"Modeling exchange-spring layered systems with perpendicular anisotropy using

ferromagnetic resonance measurements"

O 87

Silva, Maria Joao (Inst. Nacional Saude Dr. Ricardo Jorge, Portugal)

"Safety evaluation of manufactured nanomaterials: comparison of genotoxic effects of

multi-walled carbon nanotubes in two human cell lines"

O 89

Silvestre, Nuno (IST-Technical University of Lisbon, Portugal)

"Mechanical behaviour of tensioned and twisted chiral carbon nanotubes"

O 91

Simão, Claudia (Institut Català de Nanotecnologia (ICN-CIN2), Spain)

"Block copolymers directed self-assembly directed by nanoimprint: approaches and

nanometrology" O 93

Simöes, Ricardo (Institute for Polymers and Composites IPC/I3N, Portugal)

"Modeling the electrical and mechanical properties of CNT/polymer nanocomposites"

O 95

Teixeira, Vasco (University of Minho, Portugal)

"NanoVALOR: Creation and Promotion of a Competitiveness Pole in Nanotechnology for

the capitalization of R&D potential in the North of Portugal-Galicia Euroregion" O -

Thompson, Damien (Tyndall National Institute, University College Cork, Ireland)

"Modelling and design of nanostructured interfaces" OP 96

Ventura, João (Universidade do Porto, Portugal)

"Spin-dependent tunneling in CoFeB-MgO magnetic tunnel junctions"

O 97

Vieira, Maria Teresa (CEMUC-Universidade de Coimbra, Portugal)

"Reactive nanomaterials for non-conventional applications" OP 99

Vilhena Albuquerque D'Orey, Jose Guilherme (Univer. Autónoma de Madrid, Spain)

"Molecular dynamics study of the IgG adsorption on a graphite surface" OP 101


Index alphabetical order Keynotes

Page

Calado, João (Innovnano, Portugal)

“High Pressure Physics on large scale Synthesis of Nanomaterials” 25

Charra, Fabrice (CEA, France)

“Direct imaging of optical field enhancement, propagation and antenna effects for molecular

plasmonics” 28

Cuniberti , Gianaurelio (Dresden University. of Technology, Germany)

“Biosensing with Silicon Nanowire FETs: From Theory to experiments” 31

Fernández Rossier, Joaquín (INL, Portugal)

“Spin Physics in two dimensional materials: from graphene to MoS2 “ 36

Freitas, Paulo (INL, Portugal)

“Spintronic devices for biomedical applications” 42

Gaspar, Rogério (Univ. of Lisbon, Portugal)

“Nanomedicines: the clinical use and the challenges coming from new manufacturing

science and healthcare costs” 43

Hueso, Luis (CIC nanoGUNE, Spain)

“Spintronic devices with fullerenes” 51

Landman, Uzi (Georgia Inst. of Technology, USA)

"To be defined" -

Peres, Nuno (Univ. Minho, Portugal)

“Exact solution for square-wave grating covered with graphene: Surface plasmons-polaritons

in the THz range” 70

Roche, Stephan (CIN2-ICN-CSIC, Spain)

“Quantum Transport in Disordered Graphene : Scaling Properties and Spin relaxation

Mechanisms” 81

Sáenz, Juan José (Univ. Autónoma de Madrid, Spain)

“Scattering Asymmetry and Non-conservative Optical Forces on Nanoparticles” 82

Samitier, Josep (IBEC, Spain)

Functional liposome arrays based on natural nanovesicles” 86



Orals

(P lenary Sess ion)

Page

Aguilar Ribeiro, Helena (University of Porto, Portugal)

"In situ decoration of gold nanoparticles on TiO2/cellulose nanocomposites: An application

toward dye-sensitized solar cells on paper substrates" 21

Ahn, Kang-Hun (Chungnam National University, Korea)

"Anomalously strong confinement in strained graphene systems" 23

Arias Otero, Jorge (Centro de Aplicaciones Laser-AIMEN, Spain)

"To be defined" -

Braun, Hans-Georg (Leibniz Institute of Polymer Research, Germany)

"Complex structure formation in ultrathin films and at liquid/gas interfaces" 24

Chachamidou, Maria (Aristotle University of Thessaloniki, Greece)

"Commercialisation of Organic and Large Area Electronics – COLAE Project"

27

Correa-Duarte, Miguel Angel (Universidade de Vigo, Spain)

"Inorganic Complex Nanocapsules: Synthesis and Applications" 29

De la Prida, Víctor (Universidad de Oviedo, Spain)

"Electroplating of Co54Ni46/Co85Ni15 multilayer nanowires from single electrochemical bath in

anodic alumina templates" 32

dos Santos, Tiago (Instituto de Engenharia Biomédica, Portugal)

"Uptake of Polymer-Based nanoparticles of different size into multiple cell lines: approaches to

control and understand bio-nano interactions" 34

Fonseca, Joana (CeNTI -Centre for Nanotechnology and Smart Materials, Portugal)

"Printed sensors: from the printing process to the data acquisition system design" 37

Fraga, Sonia (REQUIMTE, Portugal)

"Biokinetics and toxicity of gold nanoparticles after single intravenous injection in the rat" 38

Franco, Ricardo (REQUIMTE-Universidade Nova de Lisboa, Portugal)

"Bionanotechnology for Malaria Diagnostics: Towards a Point-Of-Need Assay" 40

Glückstad, Jesper (Technical University of Denmark, Denmark)

"Structure-mediated nanoscopy" 44

Gnauck, Peter (Carl Zeiss, Germany)

"Helium Ion Microscopy. Extending the frontiers of nanotechnology"

46

González Salazar, Jhon Wilfer (INL-International Iberian Nanotechnology Lab. Portugal)

"Graphene single electron transistor as a sensor for magnetic molecules"

50

Kasumov, Alekber (Universite Paris-Sud, France)

"Long range electronic tranport in DNA molecules"

52

Korgel, Brian (Univ.of Texas at Austin/Depart. of Chemical Engineering, USA)

"Silicon and Germanium Nanowires for Next Generation High Capacity Lithium Ion Batteries"

54

Larkin, Ivan (University of Minho, Portugal)

"Edge magnetoplasmons in strongly non-uniform magnetic field"

55

Medforth, Craig (REQUIMTE -Universidade do Porto, Portugal)

"New Insights into the Synthesis and Structures of Self-Assembled Porphyrin Nanomaterials"

57


Page

Moreira, João Nuno (University of Coimbra, Portugal)

"Tailoring Nanomedicines aiming at anticancer molecular therapy"

60

Pereira, Eulalia (Universidade do Porto, Portugal)

"Nanobioconjugates of tyrosinase and laccase with gold nanoparticles: effect of coupling

method and capping agent on enzymatic activity"

68

Pérez-Prieto, Julia (Universitat Valencia, Instituto de Ciencia Molecular (ICMol), Spain)

"Symbiosis between nanoparticles and their organic ligands"

71

Rai, Akhilesh (Universidade de Coimbra, Portugal)

"Design of potent antimicrobial and biocompatible gold nanoparticles"

74

Rana, Sohel (University of Minho, Portugal)

"Development and characterization of carbon nanotube dispersed carbon/phenolic multi-

scale composites"

75

Rauls, Eva (University of Paderborn, Germany)

"Formation of thin organic layers at the example of Co- and Cu-Phthalocyanines on Au-

substrates-a theoretical investigation"

77

Rocha, Nuno (University of Coimbra , Portugal)

"Development of polymer-based self-assembly systems for advanced applications"

79

Sáez Puche, Regino (Universidad Complutense Madrid , Spain)

"Synthesis, characterization and magnetic properties of ZnFe2O4 spinel nanoparticles

encased in porous matrices"

83

Schmool, David (IFIMUP-IN, Universidade do Porto, Portugal)

"Modeling exchange - spring layered systems with perpendicular anisotropy using

ferromagnetic resonance measurements"

87

Silva, Maria Joao (Inst. Nacional Saude Dr. Ricardo Jorge, Portugal)

"Safety evaluation of manufactured nanomaterials: comparison of genotoxic effects of multi-

walled carbon nanotubes in two human cell lines"

89

Silvestre, Nuno (IST-Technical University of Lisbon, Portugal)

"Mechanical behaviour of tensioned and twisted chiral carbon nanotubes"

91

Simão, Claudia (Institut Català de Nanotecnologia (ICN-CIN2), Spain)

"Block copolymers directed self-assembly directed by nanoimprint: approaches and

nanometrology"

93

Simöes, Ricardo (Institute for Polymers and Composites IPC/I3N, Portugal)

"Modeling the electrical and mechanical properties of CNT/polymer nanocomposites"

95

Teixeira, Vasco (University of Minho, Portugal)

"NanoVALOR: Creation and Promotion of a Competitiveness Pole in Nanotechnology for the

capitalization of R&D potential in the North of Portugal-Galicia Euroregion"

-

Ventura, João (Universidade do Porto, Portugal)

"Spin-dependent tunneling in CoFeB-MgO magnetic tunnel junctions"

97



Orals

(Para l le l Sess ion)

Page

Carneiro, Joaquim (University of Minho, Portugal)

"Development of Anodic Aluminum Oxide (AAO) membranes for cell culture substrates" 26

Costa, Claudia (Ynvisible S.A., Portugal)

"PEDOT and graphene based electrodes printed by screen-printing on plastic and paper and

application on flexible electrochromic devices" 30

Evangelista, Marta B. (BIOCANT, Portugal)

"Antimicrobial peptide permanently immobilized on surfaces with high activity in the

presence of serum and low cytotoxicity against human cells " 35

Gomes, João (ISEL - Instituto Superior de Engenharia de Lisboa, Portugal)

"Assessment of nanoparticles emissions resulting from arc welding of mild steel" 48

Marques, António (CeNTI-Center for Nanotechnology and Smart Materials, Portugal)

"Transparent thin films for TCOs replacement – A Roll-to-Roll approach" 56

Melle-Franco, Manuel (University of Minho, Portugal)

"Realistic modeling of carbon nanostructures, bridging the gap between theory and experiment" 59

Moura, Vera (Treat U, Lda, Portugal)

"PEGASEMP - impact on the treatment of solid tumors with a novel microenvironment targeting" 62

Paiva, Maria da Conceiçao (Universidade do Minho, Portugal)

"The influence of carbon nanotube functionalization on the dispersion in polypropylene by

melt blending" 64

Pereira, Clara (REQUIMTE-Universidade do Porto, Portugal)

"Engineered Nanomaterials for the Development of Functional Textiles: From Concept to

Technological Applications" 66

Piedade, Ana Paul (CEMUC-GNM, Portugal)

"Sputtering and nanosurface modification of biomedical devices" 72

Salgueiriño, Veronica (Universidade de Vigo, Spain)

"Hybrid Nanostructures assembling Antiferro- and Ferrimagnetic Oxides" 85

Thompson, Damien (Tyndall National Institute, University College Cork, Ireland)

"Modelling and design of nanostructured interfaces" 96

Vieira, Maria Teresa (CEMUC - Universidade de Coimbra, Portugal)

"Reactive nanomaterials for non-conventional applications" 99

Vilhena Albuquerque D'Orey, Jose Guilherme (Universidad Autónoma de Madrid, Spain)

"Molecular dynamics study of the IgG adsorption on a graphite surface" 101

Abstracts


Helena Aguilar Ribeiro, Christiane Santos and Ana Catarina Duarte LEPAE, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal

[email protected]

I n s i t u d e c o r a t i o n o f g o l d n a n o p a r t i c l e s o n

T i O 2 / c e l l u l o s e n a n o c o m p o s i t e s : A n

a p p l i c a t i o n t o w a r d d y e -s e n s i t i z e d s o l a r c e l l s o n p a p e r

s u b s t r a t e s

Dye-sensitized solar cells (DSCs) have long been envisaged as a cost-effective alternative to conventional inorganic solid state photovoltaic technologies (PV), but further optimization of the cells performance and manufacturing processes for large scale production is still underway. The major processes occurring in a DSC include photoexcitation of dye molecules, charge generation and electron percolation within a mesoporous metal oxide semiconductor, and electron scavenging by the electrolyte ionic species [1,2]. Recent studies suggest the use of one-dimensional morphologies such as nanotubes, nanowires and fibers in an attempt of improving electron transport in the semiconductor, also providing a larger surface area for dye adsorption and enhancement of the light harvesting efficiency. Among these alternatives, photoanodes made of cellulose fibers embedded with conductive nanoparticles and photosensitizers, and with a much lower tortuosity of the pores compared to mesoporous nanoparticulated films, apparently offers a decisive advantage. In fact, with the advent of printed electronics, paper has emerged as a focus area for researchers developing innovative paper-like substrates for lightweight, flexible, electronic devices such as DSCs [3,4]. The obvious motivation of this work was to demonstrate the potential of incorporating light-harvesting nanostructures and titania nanoparticles into cross-linked cellulose fibers, and use this new material architecture as a semiconductor for DSCs. Nanosized TiO2 particles were deposited and grafted on cellulose fibers surface by using a sol-gel method at low temperature (<100 ºC) and titanium isopropoxide as the TiO2 precursor. The as-prepared paper-like semiconductor was sintered at moderate temperatures (<200 ºC) and sensitized with N719 ethanol dye solution. Complete DSCs were characterized by means of electrochemical impedance spectroscopy to elucidate how composition and topography of the composite semiconductor impact on its global performance.

Under one-third Sun - typical lower-light, real-world light conditions, tens of micro A·cm-2 were obtained with DSCs made of commercial bleached Eucalyptus

globulus kraft paper. Although this was a very promising outcome, the low electric conductivity of the paper based substrates is still envisaged as one of the main bottlenecks toward PV and printed electronic applications. To further enhance the conductivity of paper, a sort of nanostructured carbon materials could be employed but that would limit the optical properties of the semiconductor [5]. Conjugation of gold nanoparticles (AuNP) with titania and cellulose fibers became the focus of this research, as these quantum sized particles may play two important roles: (i) preservation/enhancement of the semiconductor optical properties in the UV-visible light wavelength; for small monodispersed gold quantum dots the surface plasmon resonance phenomena causes an absorption of light similar to that of N719 ruthenium based dye, with a characteristic narrow absorption band observed at 530 nm [6]; (ii) promotion of electric contact among titania aggregates [7] and cellulose fiber cross-linking [8].

Electrodes made from commercial printing paper samples, in which titania nanoparticles had previously been grafted to cellulose fibers by the in

situ precipitation method described above, were dipped into a solution of AuNPs stabilized with tannic acid and sodium citrate for 24h. After dipping, the electrodes were rinsed and dried at room temperature and used as photoelectrodes for DSCs. The performance of DSCs fabricated with AuNP@TiO2 decorated commercial bleached kraft paper grafted on FTO (F:SnO2) conductive glass was assessed by means of electrochemical impedance spectroscopy and photocurrent density vs. photovoltage characteristic data. Results are in line with previous studies reporting high adsorption of gold nanoparticles on paper, attributed to the interaction between the hydroxyl groups of the


tannin acid-metal ion complex and cellulose through hydrogen bonding and minor Van-der-Wall interactions [8].

At the present time, research is being oriented to solve scaling-up issues related to substrate film adhesion and foster the development of stable, high-performance devices for energy conversion and smart packaging solutions.

Acknowledgements: The authors acknowledge the Portuguese National Science Foundation (FCT) for financial support under the contract PTDC/EQU-EQU/101397/2008 and Programa Ciência 2007. LEPAE, CEFT, LCM and DEMM at FEUP are greatly acknowledged for the much appreciated facilities.

References

[1] M. Shalom, J. Albero, Z. Tachan, E. Martinez-

Ferrero, A. Zaban, E. Palomares, The Journal of Physical Chemical Letters, 1 (2010), 1134.

[2] K. Tvrdy, P.A. Frantsuzov, P.V. Kamat, PNAS, 108, (2010), 29.

[3] B. Wang, L.L. Kerr, Solar Energy Materials & Solar Cells, 95 (2011), 2531.

[4] K. Fan, T. Peng, J. Chen, X. Zhang, R. Li, Journal of Materials Chemistry, 22 (2012), 16121.

[5] L. Hu, J.W. Choi, Y. Yang, S. Jeong, F. La Manti, L.-F. Cui, Y. Cui, PNAS, 51 (2009), 21490.

[6] S.A. Aromal, D. Philip, Physica E, 44 (2012), 1692.

[7] D. Tsukamoto,Y. Shiraishi, Y. Sugano, S. Ichikawa, S. Tanaka, T. Hirai, Journal of the American Chemical Society, 134 (2012), 6309.

[8] A. Higazy, M. Hashem, A. ElShafei, N. Shaker, M.A. Hady, Carbohydrate Polymers, 4 (2010), 890.

Figures

Figure 1: Schematic diagram of the paper-based semiconductor grafted on fluor-doped tin oxide transparent conductive glass (FTO); SEM image of titania surface coated cellulose fibers: the inset shows a dye-sensitized solar cell made with a AuNP@TiO2/Cellulose nanocomposite electrode.


Kang-Hun Ahn1, Sul-Ah Park1,

Young-Woo Son2, Kyung-Joong Kim1 and Ya. M. Blanter3 1Department of Physics, Chungnam National University, Daejeon 305-764, Republic of Korea 2Korea Institute for Advanced Study, Seoul 130-722, Republic of Korea 3Kavli Institute of Nanosciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands

[email protected]

A n o m a l o u s l y s t r o n g c o n f i n e m e n t i n s t r a i n e d

g r a p h e n e s y s t e m s

The quasi-particles near charge neutral point in graphene are described by massless Dirac Fermions. When mechanical strain is applied to graphene, it is now well known that the strain plays a role of pseudo-magnetic field, which can be so strong to confined quasi-particles in pseudo-Landau levels. The strain engineering of graphene attracts great interest nowadays because of the huge pseudo-magnetic field which is unrealistically strong if it was real magnetic field.

We investigate electronic properties of mechanically deformed graphene systems not only near Dirac points but also other points in Brillouin zones. We introduce various phenomena which cannot be described in perturbation method.

Rotationally symmetric strain causes inhomogeneous pseudo magnetic field causing quasi-particle confinement near Dirac points. At certain energies, the quasi-particle can escape out through transport channel which can be described by ‘snake orbit’. We show that depending on the symmetries of the confined states, the system shows paramagnetic or diamagnetic response of real magnetic field [1].

We find that the electron transport of uni-directionally strained graphene is extremely sensitive to small deformation at certain momentum states. We show that the sensitivity is not originated from geometry of contacts or chaotic scattering at boundaries. We find and discuss anomalously strong confinement in this system using analytical and numerical analysis and suggest possible experiments to observe the phenomenon[2].

References

[1] Kyung-Joong Kim, Ya. M. Blanter, Kang-Hun

Ahn, Phys. Rev. B, 84 (2011) 081401(R). [2] Sul-Ah Park, Young-Woo Son, Kang-Hun Ahn,

preprint.

Figures

Figure 1: The graphene systems we consider. The graphene with rotationally symmetric strain (A) and uni-directionally deformed graphene (B).


Hans-Georg Braun Max Bergmann Center of Biomaterials, Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, D-01069 Dresden, Germany

[email protected]

C o m p l e x s t r u c t u r e f o r m a t i o n i n u l t r a t h i n f i l m s a n d a t

l i q u i d / g a s i n t e r f a c e s

Self organization of different systems at interfaces or in ultrathin films will be discussed.

Ultrathin (3nm) Polyethyleneoxide (PEO) films (left upper image) which are initially amorphous and metastable can self-assemble into dendritic lamella structures during crystallization. Patterning of the amorphous films will demonstrate the influence of surface confinement onto the diffusion limited growth process (DLA) that takes place [1].

The pH triggered aggregation of oligopeptide molecules ( FmocFF) at the liquid/gas interface will be shown to produce nanosized networks of peptide fibrills which are crystallographically characterized by electron diffraction. (right upper image) [2].

The formation of calziumcarbonate microparticles at the liquid/gas interface which self-assembly into extended (meter sized) stable floating rafts (left lower image) is another example of interfacial self-assembly. The stability of free floating rafts at the liquid/gas interface will be discussed on artifical microstrcutured floating membranes with predefined pore sizes (right lower image) [3]. References

[1] E. Meyer & H.-G. Braun, Journal of Physics, 17

(2005) S623 – S635 [2] H.-G. Braun & A. Zamith-Cardoso, Colloids and

Surfaces B: Biointerfaces 97 (2012) 43-50 [3] René Hensel and Hans-Georg Braun, Soft

Matter, 2012,8, 5293-5300

Figures


J. Calado, N. Neves, R. Calinas, A Lagoa, S Pratas and M Rodrigues Innovnano, Materiais Avançados, SA, Coimbra, Portugal

[email protected]

H i g h P r e s s u r e P h y s i c s o n l a r g e s c a l e S y n t h e s i s o f

N a n o m a t e r i a l s

INNOVNANO is a Portuguese company with an innovative industrial nanomaterials synthesis process that has the ability to produce customizable, high quality nano-structured powders with excellent physical, chemical and mechanical properties. Production capacity increases significantly with the opening of a new manufacturing and technology facility (Coimbra, Portugal) in middle of 2012. The new plant technology is based on a patented process [1], where a broad range of nanomaterials are obtained at very high dynamic pressures (3-10 GPa).

In this talk, I will discuss, in a theoretical point of view, the effect of high pressure phenomena during the gas phase synthesis of nanomaterials, in variables like: condensation conditions of nanoparticles, saturated vapor pressure, free enthalpy of formation of a stable aggregate and the critical minimum germ size.

The second step analysis will be focused on the effect of high dynamic pressures on the final properties that nanomaterials acquire when subjected to dynamic high pressure: shock induced phase transitions and chemical reactions, defects and flux pinning, super hardness and nanocrystallinity.

To conclude, I will present some Innovnano R&D results [2,3], around a narrow range of very specific nanomaterials and nanotechnology applications: Nanocoatings for TBC´s, Advanced Ceramic Applications, Translucent Ceramic pieces, Photovoltaic Applications, Lithium ion-batteries, where these nanomaterials are currently being applied and intensively tested.

References

[1] Calado, J.M. and Antunes, E.M., Nanometric-

sized ceramic materials, process for their synthesis and uses thereof, patent WO 2009144665 (2009).

[2] Neves, N., Barros, R., Antunes, E., Ferreira, I., Calado, J., Fortunato, E. and Martins, R., Aluminum doped zinc oxide sputtering targets obtained from nanostructured powders: processing and application, J. Eur. Ceram. Soc., 2012, 32(16) 4381-91.

[3] Carvalho, T., Antunes, E., Calado, J., Figueiredo, F.M. and Frade, J.R., Lanthanum oxide as a scavenging agent for zirconia electrolytes. Solid State Ionics, 2012, 225, 484-7.


J. Carneiro1, M. Peixoto1, P.

Sampaio2, A. Samantilleke1, S. Azevedo1, F. Fernandes1, M. Maltez-da Costa1, V. Teixeira1 1Physics Department, University of Minho, Azurém Campus, 4800-058, Guimarães, Portugal 2Centre of Molecular and Environmental Biology (CBMA), University of Minho, Campus of Gualtar, 4710-057 Braga, Portugal

[email protected]

D e v e l o p m e n t o f A n o d i c A l u m i n u m O x i d e ( A A O )

m e m b r a n e s f o r c e l l c u l t u r e s u b s t r a t e s

Nanoporous Anodic Aluminum Oxide (AAO) structures have become the object of intense scientific research works for dissimilar fields of application. These structures are characterized by the presence of parallel pores with perpendicular orientations to the surface. The pore dimension depends on the applied voltage, electrolyte concentration (and type) and temperature [1]. The unique properties and structure of nanoporous AAO seems beneficial in biomedical fields, such as tissue engineering [2]. Recent studies have dealt with the application of nanoporous aluminum oxide films on orthopedic implants since nanostructured membranes present excellent cell-growth conditions. The cells are able to grow into the pores and consequently stabilize the endoprosthesis.

The main goal of this work was the production of nanoporous AAO membranes in sulfuric acid electrolyte using a two-step anodization process for the cell culture substrates. The influence of anodization process’ parameters (i.e. applied voltage, current intensity and electrolyte

concentration as well as temperature) on membranes’ pore morphology was evaluated (pore size, inter-pore distance and thickness). Moreover, in what concerns the biological experiments, the cytotoxicity (LDH and TNF-α measurement) of the AAO membranes was tested. Additionally, by using Scanning Electron Microscopy (SEM) it was possible to evaluate the influence of pore diameters on cells adhesion and its proliferation.

References

[1] W. Lee, K. Schwirn, M. Steinhart, E. Pippel, R.

Scholz and U. Gösele, Nature Nanotechnology 3 (2008) 234 - 239

[2] A. Hoess, N. Teuscher, A. Thormann, H. Aurich, A. Heilmann, Acta Biomaterialia, 1 (2007) 43


Maria Chachamidou, Stergios Logothetidis

Aristotle University of Thessaloniki, Department of Physics, Lab for Thin Films- Nanosystems & Nanometrology (LTFN), GR-54124 Thessaloniki, Greece

[email protected]

C o m m e r c i a l i s a t i o n o f O r g a n i c a n d L a r g e A r e a E l e c t r o n i c s –

C O L A E P r o j e c t

The area of Organic and Large-area Electronics (OLAE) is a new scientific and technological field of Nanotechnology with a multitude of potential applications that offer substantial advantages and the possibility for low cost large-scale manufacturing processes in high volumes. Most new technical and business opportunities are perceived to be in energy (Organic Photovoltaics- OPV), displays (Organic Light Emitting Diodes- OLEDs), lighting, signage, sensors (Organic Thin Film Transistor- OTFT), smart labeling and medicine (Organic Biosensors) [1, 2]. The applications of Organic Electronics are already penetrating every commercial and industrial field, aiming to dominate every aspect of life worldwide [3].

Europe has been pulling ahead of the rest of the world in many aspects of OLAE and probably has the most robust vertical integration of effort in OLAE. Actors in OLAE field in Europe involve several big companies, corporate and academic spin-offs [4], start ups as well as Universities and Research Institutes across various European countries that have contributed greatly to the growth of what is widely recognized to be a commercial prospect with immense potential [5]. Since OLAE technologies are becoming ready for incorporation into products of all types there is a need for technology transfer and research commercialization.

Europe’s leading organizations are collaborating to form COLAE – Commercialization of Organic and

Large Area Electronics – a European funded project under the Seventh Framework Programme [6]. The project is designed to promote the commercial exploitation of OLAE technology for the benefit of European industry. COLAE aims to provide to European companies effective access to the knowledge base and technology know-how of key European OLAE partners and their regional OLAE clusters, high-quality training, OLAE product and business idea feasibility support, the best European manufacturing, pilot production facilities and services, important future research topics through workshops, advanced OLAE open innovation process and

coordinated support for better IPR landscaping and exploitation.

The expected impacts of COLAE include the growth of OLAE R&D services in Europe, increased effective product demonstration and pilot services, the improved coordination of infrastructure investments, the enlargement of the network of OLAE companies and an increase in the number and capability of OLAE technologists and designers. To achieve this, project activities include awareness of the opportunities given by OLAE. COLAE provides evaluation and verification of opportunities and provides a coordinated support service for their needs. A program of training, providing basic awareness as well as more advanced technology and entrepreneurship courses is being implemented. An OLAE feasibility network is being established and verified by executing selected trial cases in which new users of OLAE will be assisted to examine the feasibility of using OLAE technology into applications. The OLAE feasibility network is an important step towards the concept of a virtual European OLAE foundry, together with the development of an open innovation model for collaboration and rapid commercialization of OLAE.

References

[1] Strategic Research Agenda Organic & Large Area Electronics (2009)

[2] Logothetidis S., Materials Science and Engineering: B, Volume 152, Issues 1–3, 25, Flexible organic electronic devices: Materials, process and applications (2008), 96-104

[3] Intertechpira. Printed, Organic & Flexible Electronics Forecasts, Players & Opportunities 2012-2022, http://www.idtechex.com (2012)

[4] Chachamidou, M. & Logothetidis, S., Proceedings of the 2nd International Symposium on Flexible Organic Electronics, Academic entrepreneurship: the case of organic electronics (2009).

[5] Organic Electronics Association (OE-A), Roadmap for Organic and Printed Electronics (2011)

[6] COLAE Project- Commercialization of Organic and Large Area Electronics www.colae.eu (2012)


Fabrice Charra Laboratoire de Nanophotonique, Service de Physique et Chimie des Surfaces et Interfaces, IRAMIS, CEA, F-91191 Gif-sur-Yvette Cedex, France

[email protected]

D i r e c t i m a g i n g o f o p t i c a l f i e l d e n h a n c e m e n t , p r o p a g a t i o n

a n d a n t e n n a e f f e c t s f o r m o l e c u l a r p l a s m o n i c s

The exploitation of plasmon resonances to promote the interaction between conjugated molecules and optical fields motivates intensive researches. Their objectives are to understand the mechanisms of plasmon-mediated interactions, and to realize molecularly- or atomically-precise metal nanostructures combining field-enhancements and optical antenna effects. In this presentation, we present examples of plasmonic-field mappings based on multiphoton photoemission PEEM [1], or scanning tunneling microscopy(STM)-induced light emission [2], two techniques among those which offer today's best spatial resolutions for plasmon microscopy [3].

By imaging the photoemitted electrons, using well-established electron optics, two-dimensional intensity maps reflecting the actual distribution of the optical near-field are obtained. The imaging technique involves no physical probe altering the measure. This approach provides full field spectroscopic images with a routine spatial resolution of the order of 20 nm (down to 2 nm with recent aberration corrected instruments). We have analyzed the optical response of various metal nano-objects and imaged for the first time the so-called short-range propagative modes in nanorods [4] as well as polarization and spectral selection of hot-spots at the tips of gold nano-triangles [5] or nano-stars [6].

A particularly interesting geometry is that of a nano-scale gap between two metallic objects, as present between the tip and the sample in a STM. Such geometry is ideally suited to exhibit simultaneously field enhancement and antenna effects. Hence, an unfamiliar property of the junction of a STM is its ability to behave as a highly localized source of light. This phenomenon can be exploited to probe opto-electronic properties, in particular plasmonic fields, with ultimate subnanometer spatial resolution. Moreover, it permits to insert molecular systems in

the junction, in particular through self-assembly. The analysis of current- or field induced photonic processes in the junction of a STM operating in an organic environment offers new insights into elementary mechanisms underlying photonic responses. We have studied the response of self-assembled metal particles and conjugated organic systems [7]. Time-resolved or nonlinear optical processes may be exploited as well [8].

As a conclusion, we will report an application of plasmonics in two-photon fluorescence (TPF) enhancements through nanoantenna or Purcell effects in hybrid systems coupling gold nanoparticles to fluorophores. First results indicate the existence of an optimal distance between fluorophore and metal surface, allowing TPF enhancement [9]. References

[1] L. Douillard et al., Journal of Applied Physics

101, 083518 (2007). [2] F. Silly et al., Physical Review Letters 84 (2000). [3] L. Douillard, and F. Charra, Journal of Physics D-

Applied Physics 44, 464002 (2011). [4] L. Douillard et al., Nano Letters 8 (2008). [5] C. Awada et al., Journal of Physical Chemistry C

116 (2012). [6] C. Hrelescu et al., Nano Letters 11 (2011). [7] K. Kusova et al., Surface Science 602 (2008). [8] I. Berline et al., Journal of Applied Physics 104,

103113 (2008). [9] Y. El Harfouch et al., Proceedings of SPIE 8424,

842418 (2012).


Miguel A. Correa-Duarte and Moisés Pérez-Lorenzo Department of Physical Chemistry, Universidade de Vigo, 36310 Vigo, Spain

[email protected]

I n o r g a n i c C o m p l e x N a n o c a p s u l e s :

S y n t h e s i s a n d A p p l i c a t i o n s

The synthetic architectures of complex nanostructures, including multifunctional hollow capsules, are expected to play key roles in many different applications, such as drug delivery, photonic crystals, nanoreactors, and sensing. Implementation of novel strategies for the fabrication of such materials is needed because of the infancy of this knowledge, which still limits progress in certain areas. Herein we report a straightforward synthetic approach for the development of multifunctional submicron reactors comprising catalytic and or optically active nanoparticles confined inside porous hollow silica capsules. The confined growth of encapsulated metal nanoparticles was carried out to evidence the usefulness and functionality of these reactors in different applications, such as bio-sensing based on surface enhance Raman spectroscopy (SERS) [1], or in catalysis. Additionally, it has been used as an innovative approach for the development of novel complex nanostructures [2].

References

[1] Sanles-Sobrido, M.; Exner, W.; Rodríguez-

Lorenzo, L.; Rodríguez-González, B.; Correa-Duarte, M. A.; Alvarez-Puebla, R. A.; Liz-Marzán, L. M., J. Am. Chem, 131 (2009), 2699–705.

[2] Sanlés-Sobrido, M.; Pérez-Lorenzo, M.; Rodríguez-González, B.; Salgueiriño, V.; Correa-Duarte, M. A., Angewandte Chemie 51 (2012), 3877–82.

Figures

Figure 1: Synthesis of Ni/NiO magnetic nanostructures by controlled reactions carried out in the inner cavity of the previously formed nanoreactor. a) Hybrid particles composed of dendritic Pt NPs deposited onto polystyrene (PS) colloidal templates; b) hollow capsules obtained after the silica coating and polymer dissolution processes; c) formation of magnetic Ni nanomaterial confined inside the silica hollow capsule by reduction of the Ni2+ ions using hydrazine and catalyzed with the dendritic Pt NPs.


Lúcia Gomes, Tiago Moreira, Aida Branco, Cláudia Costa, Ana Marques Ynvisible, Rua Mouzinho de Albuquerque 7, 2070-104 Cartaxo, Portugal

[email protected]

P E D O T a n d g r a p h e n e b a s e d e l e c t r o d e s p r i n t e d b y s c r e e n -p r i n t i n g o n p l a s t i c a n d p a p e r

a n d a p p l i c a t i o n o n f l e x i b l e e l e c t r o c h r o m i c d e v i c e s

The present work describes the deposition of PEDOT and graphene based films on plastic and paper using screen-printing. Electrochromic devices (ECDs) were assembled using these PEDOT/graphene based electrodes.

Over the last years, the use of transparent conductive electrodes (TCE) has been growing for many different applications in areas such as portable electronics, displays and flexible electronics; a few examples are multi-functional windows, touchscreens, solar cells, transistors and electrochromic devices (ECD). Lately, the integration of ECDs in disposable applications has gained a growing interest in the printed electronics field.

The most commonly used TCE is indium-tin oxide (ITO), which, in most cases, is used as a thin film sputtered onto glass or plastic. However, this material has several limitations and possible alternatives are being extensively studied.

PEDOT is a conductive polymer with a strong blue coloration and is used both as a conductive material, as well as an electrochromic material. Doping PEDOT with carbon-based materials results in films with higher transparency, as well as higher conductivity,

which still maintain the electrochromic functionality of PEDOT and its electrochemical reversibility. The main objective of this work is to print a single layer of PEDOT/graphene formulations that acts as electrode and electrochromic material simultaneously when assembled in electrochromic devices (thereby reducing the conventional 5 layer device to a 3 layer device). The hybrid PEDOT/graphene formulation can also be used to print transparent electrodes for other devices that do not involve redox reactions.

Several PEDOT/graphene formulations were prepared and printed. The resulting thin films were characterized in terms of electrical and optical properties, as well as stability measurements. Techniques such as cyclic voltammetry, UV-Vis spectroscopy, SEM and mechanical tests (tape peeling test, scratch test and bending test) were used. The performance of the resulting devices was compared with that of conventional ones (5 layer structure) through the analysis of the device color contrast over time during continuous operation conditions using a cycling program.


Gianaurelio Cuniberti Chair "Materials Science and Nanotechnology" Institute for Materials Science and Max Bergmann Center of Biomaterials Dresden University of Technology 01062 Dresden, Germany

[email protected]

B i o s e n s i n g w i t h S i l i c o n N a n o w i r e F E T s : F r o m T h e o r y

t o e x p e r i m e n t s

Mobile and automated biosensing is a key technological issue for modern medicine. Current medical diagnostics rely on laboratory methods that are very exact and reliable, however lacking the possibility of miniaturization and cost-efficiency for point-of-care diagnostics and personalized medicine.

During the past decade field effect transistors mainly based on doped silicon were adapted for highly sensitive detection of biological molecules based on charge sensing. We are here presenting our work on the manufacturing, characterization and theoretical modeling of a Schottky barrier silicon nanowire field effect transistor for the detection of biological molecules.

A multi-scale model for the determination of nanowire conductivity was developed and applied to Schottky barrier nanowire FETs in dry and liquid surrounding. In parallel electrical measurements that show the device's biosensing capabilities were done and underlying mechanisms were explained by theoretical predictions.

In conclusion we developed a low cost Schottky barrier nanowire field effect transistor and we were able to model the device sensitivity. Our devices have the potential to improve diagnostics in modern medical applications.


V.M. Prida1, J. García1, L. Iglesias1, V.

Vega1, D. Görlitz2, K. Nielsch2, E. Díaz Barriga-Castro3, R. Mendoza-Résendez4, A. Ponce5 and C. Luna3 1 Depart de Física, Univ de Oviedo, (Spain) 2 Inst of Applied Physics, Univ of Hamburg, (Germany). 3 Centro de Investigación en Ciencias Físico Matemáticas / Facultad de Ciencias Físico Matemáticas, Universidad Autónoma de Nuevo León, (México) 4 Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, (México) 5 Depart of Physics and Astronomy, Univ of Texa,s (USA)

[email protected]

E l e c t r o p l a t i n g o f C o 5 4 N i 4 6 / C o 8 5 N i 1 5 m u l t i l a y e r

n a n o w i r e s f r o m s i n g l e e l e c t r o c h e m i c a l b a t h i n

a n o d i c a l u m i n a t e m p l a t e s

Co-Ni alloy nanowires are outstanding magnetic materials that can exhibit either a soft or a hard magnetic behaviour depending on the Co content in the alloy [1, 2]. The combination of low magnetocrystalline anisotropy of fcc Ni and high magnetocrystalline anisotropy of hcp Co, together with the high solubility of Co atoms in the Ni crystalline lattice and vice-versa, for a wide range of relative concentrations, allows for the design of material composition with tunable magnetic properties [3]. Additionally, the anomalous electroplating behaviour of the Co-Ni alloys results in a preferential deposition of Co atoms with respect to the Ni ones, although Ni2+ ions have a slightly higher deposition potential than Co2+ ions [4]. This effect becomes predominant at low deposition potentials (-0.8V vs. Ag/AgCl ref. electrode), but it is greatly reduced as the electrode potential is increased up to -1.4V vs. Ag/AgCl ref. electrode.

By using the anomalous co-electrodeposition of Co-Ni alloys, we have produced multilayered Co-Ni nanowires from a single Watts-type electrochemical bath containing Co2+ and Ni2+ ions. Hard-Anodic Aluminum Oxide (H-AAO) nanoporous alumina membranes were employed as templates to obtain highly ordered arrays of Co-Ni multilayered nanowires with a diameter of about 180 nm. The composition of each layer was modified by carefully adjusting the pulsed electrodeposition potential

between -0.8V and -1.4V vs. Ag/AgCl reference electrode [5].

The nanowires morphology, crystalline structure and chemical composition were characterized by Scanning Electron Microscopy (SEM, JEOL-6610LV), High-Resolution Transmission Electron Microscopy (HR-TEM, FEI-Titan 80-300kV), Selected Area Electron Diffraction (SAED) and Electron Dispersive X-ray Spectroscopy (EDX). Magnetic hysteresis loops were measured in a Vibrating Sample Magnetometer (VSM, Quantum Design-Versalab) under a magnetic field of ± 30 kOe, applied in both parallel and perpendicular directions with respect to the nanowires long axis.

Our studies reveal that the nanowires are composed of a stack of 40 multilayers with an average length of about 300 nm and approximated compositions of Co54Ni46 and Co85Ni15 in each layer. Figure 1 displays a TEM image of nanowires after being released from the H-AAO template. The compositional contrast indicates the different composition of the multilayers, whereas SAED spectra (insets in Figure 1) demonstrate that nanowires exhibit a differenced crystalline structure between each layer, corresponding to fcc or hcp phases in the Co54Ni46 or Co85Ni15 layers, respectively.

The hysteresis loops depicted in Figure 2 show small coercive field values of HC = 150 and 194 Oe for the parallel and perpendicular directions, respectively.


The reduced remanence (mr = Mr/MS) in both directions takes values close to 0.04. These results point out that the array of nanowires does not clearly show an easy magnetization axis, indicating that the shape magnetic anisotropy of the system is strongly competing with the magnetocrystalline anisotropy and dipolar interactions among adjacent barcode nanowires having layers with different compositions and crystalline structures.

References

[1] S. Talapatra, X. Tang, M. Padi, T. Kim, R. Vajtai,

G.V.S. Sastry, M. Shma, S.C. Deevi, P.M. Ajayan, J. Mater. Sci. 44 (2009) 2271.

[2] L.G. Vivas, M. Vázquez, J. Escrig, S. Allende, D. Altbir, D.C. Leitao, J.P. Araujo, Phys. Rev. B 85 (2012) 035439.

[3] S.L. Cheng, C.N. Huang, Synth. React. Inorg., Met.-Org., Nano-Met. Chem. 38 (2008) 475.

[4] L. Tian, J. Xu, C. Qiang, Appl. Surf. Sci. 257 (2011) 4689.

[5] L. Clime, S.Y. Zhao, P. Chen, F. Normandin, H. Roberge, T. Veres, Nanotechnology 18 (2007) 435709.

Figures

Figure 1: HR-TEM image of multilayered Co54Ni46/Co85Ni15 nanowires. The insets show SAED spectra of two layers with different compositions, evidencing the change in their crystalline structures.

-10 -5 0 5 10

-1.0

-0.5

0.0

0.5

1.0

-0.2 0.0 0.2-0.05

0.00

0.05

M/M

S

Magnetic Field (kOe)

M/M

S

Magnetic Field (kOe)

Parallel

Perpendicular

Figure 2: Hysteresis loops of multilayered Co54Ni46/Co85Ni15 nanowires measured in the parallel and perpendicular directions with respect to the nanowires long axis. The inset shows an enlargement at the low field region.


Tiago dos Santos1,2, Juan Varela1,

Iseult Lynch1, Anna Salvati1 and Kenneth A. Dawson1 1Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland 2Instituto de Engenharia Biomédica (INEB), Porto, Portugal

[email protected]

U p t a k e o f p o l y m e r - b a s e d n a n o p a r t i c l e s o f d i f f e r e n t s i z e

i n t o m u l t i p l e c e l l l i n e s : a p p r o a c h e s t o c o n t r o l a n d

u n d e r s t a n d b i o - n a n o i n t e r a c t i o n s

Nanoparticles potentially provide a powerful tool for specific treatments of diseases, acting as a drug delivery transport. However, a deep understanding and control of how nanoparticles interact with biological systems is a key driver to assure the safe implementation of nanomedicine. The overall idea of this project was to provide new leads in the development of such a new field, finding tools for various biomedical applications, not only in drug delivery and gene therapy, but also in molecular imaging and biomarkers, with a better engineered nanoparticle as the ultimate goal. For this we investigated how the basic unit of life, the cell, interacts with nanoparticles. Multiple cell lines were used and the ultimate goal was to control and quantify uptake of a series of negatively charged carboxylated modified polystyrene of different size, understand the endocytic pathways required for NPs internalization, and their final sub-cellular destination. We found that kinetic models can be used to determine uptake and distinguish between uptake of molecules and nanoparticles, based on the competing kinetics of internalization and export from cells. Uptake of nanoparticles is an energy dependent process and it is linear in the first hours, saturating only at longer time scales, due to cell division [1]. Moreover, was found that internalization of nanoparticles is highly size dependent for all cell lines studied, with the different cell types showing very different uptake efficiencies for same materials, with macrophages having the higher uptake rate for all nanoparticle sizes [2] (Figure 1). In the studies of the effects of transport inhibitors, it became very clear that nanoparticle internalization might involve several different mechanisms even in one cell line, although whether this was a result of the lack of inhibitor

specificity or evidence of the use of several uptake pathways simultaneously is not yet resolved [3].

Figure 1: Confocal images of a) HeLa, b) A549, c) 1321N1, d) HCMEC/D3, e) RAW 264.7 cells treated for 24h with 20 µg/ml of 1µm diameter carboxylated modified polystyrene particles. Images represent optical section (x, y-axis), with respective projection of the x,z- and y, z-axes of a single cell, after 24h incubation with 20 µg/ml, 1µm diameter carboxylate-modified polystyrene particles.

References

[1] Anna Salvati, Christoffer Aberg, Tiago dos

Santos, Juan Varela, Paulo Pinto, Iseult Lynch, Kenneth Dawson, Nanomedicine: nanotechnology, biology and medicine, 7, (2011), 818-826

[2] Tiago dos Santos, Varela J, Lynch I, Salvati A, Dawson KA, Small, 7, (2011), 3341-3349

[3] Tiago dos Santos, Varela J, Lynch I, Salvati A, Dawson K, PloS One, 6(9), (2011), 1-9


Akhilesh Rai1,2, Marta B.

Evangelista1,2, Sandra Pinto2 and

Lino S. Ferreira1,2 1BIOCANT, Parque Tecnológico de Cantanhede, Cantanhede, Portugal 2CNC, Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Coimbra, Portugal

[email protected]

A n t i m i c r o b i a l p e p t i d e p e r m a n e n t l y i m m o b i l i z e d o n

s u r f a c e s w i t h h i g h a c t i v i t y i n t h e p r e s e n c e o f s e r u m a n d

l o w c y t o t o x i c i t y a g a i n s t h u m a n c e l l s

Antimicrobial peptides (AMPs) are a class of molecules that are present in large number in nature and are very effective against several strains of bacteria, fungi and viruses, preventing by several mechanisms infections and contaminations [1, 2]. Because they quickly kill, and target the organisms’s membrane nonspecifically, they have been shown to be less likely to develop resistant bacteria than traditional antibiotics [1]. In recent years, AMPs have been chemically immobilized on surfaces of medical devices to render them with antimicrobial properties [3-8]. However, the impact of immobilized AMPs in human cells remains elusive.

Here we report an AMP coating that can be applied to various surfaces while maintaining its antimicrobial activity in the presence of human serum while being non-cytotoxic against human cells. The coating consists on the covalent immobilization of the antimicrobial peptide cecropin-mellitin (CM) on gold (Au) nanoparticles (NPs) immobilized on surfaces. CM peptide is a hybrid antimicrobial peptide with 15 amino acids, containing sequences from cecropin-A and mellitin antimicrobial peptides. We show that we can immobilize larger concentrations of AMP peptide per centimeter square (1.02 mg/cm2) than by methods reported in the literature [5, 7, 9, 10]. The CM peptide immobilized on the Au NP-coated titanium surfaces maintains antimicrobial activity in the presence of human serum with an excellent reusability for five cycles. We further show that the surfaces having immobilized CM have little impact in cell viability, cell metabolism, membrane cell integrity and membrane cell potential as measured by different tests, and thus can be considered as relatively not cytotoxic.

Acknowledgments The authors are grateful for finantial support from Portuguese Foundation for Science and Technology Killmicrob Project under the contract PTDC/Qui-Qui/105000/2008.

References

[1] Hancock RE, Sahl HG, Nat Biotechnol 24 (2006)

1551. [2] Zasloff M, Nature 415 (2002) 389. [3] Bagheri M, Beyermann M, Dathe M, Antimicrob

Agents Chemother 53 (2009) 1132. [4] Ferreira L Zumbuehl, A, J Mater Chem 19

(2009) 7796. [5] Gabriel M, Nazmi K, Veerman EC, Nieuw

Amerongen AV, Zentner A. Bioconjug Chem 17 (2006) 548.

[6] Gao G et al. Biomacromolecules 12 (2011) 3715. [7] Gao GZ et al. Biomaterials 32 (2011) 3899. [8] Humblot V et al. Biomaterials 30 (2009) 3503. [9] Kazemzadeh-Narbat M. et al. Biomaterials 31

(2010) 9519. [10] Chen CP, Wickstrom E. Bioconjug Chem 21

(2010) 1978.


J. Fernández-Rossier1,2

1International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga, 4715-330 Braga, Portugal 2Depto. de Física Aplicada, Universidad de Alicante, 03690 Alicante, España

[email protected]

S p i n P h y s i c s i n t w o d i m e n s i o n a l m a t e r i a l s : f r o m

g r a p h e n e t o M o S 2

The study of truly two dimensional systems made of a single atomic plane extracted from a layered material has opened a new chapter in the field of material science. Whereas the paradigmatic case of graphene is being very widely studied, the fabrication of devices based on single atomic planes of transition metal dichalcogenides such as MoS2 is following suit.

In this talk I will discuss, from the theory standpoint, spin-related physical phenomena that are unique to this new class of two dimensional materials. In the case of graphene, I will discuss an intrinic spin relaxation originated by the interplay of atomic spin-orbit interaction and the local curvature induced by flexural distortions of the atomic lattice, typical from membrane like materials [1]. The proposed mechanism dominates the spin relaxation in high mobility graphene samples and should also apply to other planar aromatic compounds.

In the case of MoS2, and after a brief introduction to the properties of this semiconducting material, I will discuss the unique electronic properties of spin properties related to the lack of inversion symmetry specific of the single atomic plane. The electronic and spin properties of heterostructures of MoS2 and the related compound WS2 will also be discussed. References

[1] S. Fratini, D. Gosálbez-Martínez, P. Merodio

Cámara, J. Fernández-Rossier arXiv:1202.6216 [2] K. Kośmider, J. Fernández-Rossier

arXiv:1212.0111


Joana Fonseca, Miguel Silva, Bruna Moura, Miguel Ribeiro and João Gomes CeNTI – Centre for Nanotechnology and Smart Materials, Rua Fernando Mesquita, 2785, Vila Nova de Famalicão, Portugal

[email protected]

P r i n t e d s e n s o r s : f r o m t h e p r i n t i n g p r o c e s s t o t h e d a t a

a c q u i s i t i o n s y s t e m d e s i g n

Over the last years, the development of printed electronics has been growing rapidly. The main driving force has been the need for mass-production processes for the realization of very low cost devices. Typically, "Printed electronics" term refers to the use of different techniques such as screen printing, inkjet, or flexo/gravure. These are well-known technologies from graphics art industries that can also be used for the production of electronic components and devices such as OLEDs lamps, TFTs, RFID tags, antennas, displays, solar cells and sensors.

The printing processes allow a directed, reproducible (and therefore reliable) sensor application on a great variety of substrates, including paper and plastic and even on non-planar surfaces, reducing integration costs.

Due to major scientific and technologic efforts, printed sensors sensitive to temperature, touch, humidity, pressure, chemical compounds and light have already been achieved. In common, all of them are extremely flexible, lightweight and thin (few microns) being particularly suitable to be embedded in conventional products. Target applications include environmental monitoring (e.g. radiation tags), biomedical devices (e.g. disposable medical sensors), robotics (e.g. smart skin technology) and smart packaging (e.g. temperature tracking of pharmaceuticals, packaging designed to ensure the authenticity of branded products) [1].

At CeNTI we have been developing resistive and capacitive sensors printed by different techniques directly on different substrates (of different materials and morphologies) in close collaboration with industrial partners. A multi-disciplinary approach has been pursued focused in different steps that range from the optimization of the design and the deposition of sensors, the mechanical, morphologic and electrical characterization of the printed features and also the design and integration of the system for acquisition, treatment and data transmission. Due to the nature of the collaboration (which involves industrial partners), the scalability of the processes that are used is also one of the major focuses of the scientific and technological approaches. References

[1] http://www.azom.com/article.aspx?ArticleID=5175


Ana Brandão1, Maria Elisa Soares1, José Alberto Duarte2, Laura Pereira3, Eulália Pereira4, Maria de Lourdes Bastos1, Helena Carmo1,Sónia Fraga

1 1REQUIMTE, Laboratory of Toxicology, Department of Biological Sciences, University of Porto, Portugal 2CIAFEL, Faculty of Sports, University of Porto, Portugal 3Laboratory of Biochemistry, Department of Biological Sciences, University of Porto, Portugal 4REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto; Portugal

[email protected]

B i o k i n e t i c s a n d t o x i c i t y o f g o l d n a n o p a r t i c l e s a f t e r

s i n g l e i n t r a v e n o u s i n j e c t i o n i n t h e r a t

Gold nanoparticles (AuNPs) offer great biomedical potential as immunodiagnostic, drug/gene delivery and contrast agents [1]. A significant effort has been done to develop surface coatings in order to increase AuNPs stability and biocompatibility, which are crucial for their successful implementation into the clinical setting. The pentapeptide CALNN (cysteine-alanine-leucine-asparagine-asparagine) has been found to effectively convert citrate-stabilized AuNPs into stable, water-soluble AuNPs, with some chemical properties analogous to those of proteins [2]. Recently, our group reported that CALNN capping significantly increased hepatic accumulation of AuNPs comparing with citrate-coated AuNPs, at 24 h after a single intravenous (i.v.) injection in the rat [3]. Therefore, the present study aimed at providing further insight into the kinetics and toxicity effects of Cit-AuNPs vs CALNN-AuNPs (16 nm), after a single i.v. injection (0.7 mg Au/Kg) in the rat.

Male Wistar rats (150-200 g; n=5/group) were randomly divided into three experimental groups: control (0.9% NaCl), Cit-AuNPs and CALNN-AuNPs. At 30 min and 28 days after injection, the distribution of Cit- and CALNN-AuNPs was evaluated based on the Au tissue content measured by Graphite Furnace Atomic Spectroscopy (GFAAS) [3]. The animals were kept in metabolic cages and, in addition to clinical and behaviour observations, animal weight, food and water intake were recorded daily during the 28 days. Also, feces were collected and assayed for Au excretion. At the end of the study, the rats were sacrificed and blood samples were collected for hematology and serum ionogram analysis. Potential toxicity of the AuNPs was also investigated by determining the organ indexes and

morphological analysis of the hepatic and splenic tissue of AuNPs-injected animals by Transmission Electron Microscopy (TEM).

No abnormal clinical signs and behavioural responses were observed in either control or AuNPs-injected rats throughout the experiment. Also, no changes in the body weight, food and water intake were detected in Cit- and CALNN-AuNPs-treated animals comparing with control rats. The pattern of AuNPs distribution was very similar in the two assessed time-points (30 min and 28 days), either in Cit- or CALNN-AuNPs-treated rats (Table 1). Both Cit-AuNPs and CALNN were quickly removed from the bloodstream and preferentially accumulated in the liver. However, Au blood levels detected 30 min post-injection of CALNN-AuNPs were significantly lower comparing with citrate-AuNPs injected rats, suggesting that CALNN capping may not be effective in increasing the plasma half-life of the AuNPs. Twenty eight days post-injection, the liver remained the main accumulation site but at significantly lower levels compared to those found at 30 min after injection, suggesting elimination of the AuNPs. This hypothesis was confirmed by the presence of Au in 5-day fecal samples of AuNPs injected animals and further supported by TEM observations of the hepatic tissue, which demonstrated that AuNPs were located in Kupffer cells but not in hepatocytes, indicating that both Cit- and CALNN-AuNPs are being eliminated by the hepatobiliar pathway. Gross necropsy did not show any adverse effects of the tested AuNPs in any organs. Although no signs of AuNPs have been detected by TEM in the splenic tissue of either Cit- or CALNN-AuNPs rats, the spleen index of CALNN-injected rats was significantly lower


comparing with control rats, at 28 days post-injection. The hematological findings revealed signs of slight anaemia in CALNN-AuNPs rats with significant decreases in red blood cells (RBC), hemoglobin (HGB), hematocrit (HCT) and mean corpuscular volume (MVC). On the other hand, no changes in the electrolyte levels of sodium (Na), potassium (K) and chloride (Cl) were found in both Cit- and CALNN-treated rats.

Thus, our results confirm that the liver is the preferential organ for accumulation of Cit-AuNPs and CALNN-AuNPs. Under our experimental conditions, surface coating seems to have more impact on the toxicity rather than on the distribution of the NPs throughout the rat body.

Nevertheless, further investigation is necessary to better assess and understand the potential long-term effects of these AuNPs.

References

[1] Dykman L, Khlebtsov N, Chem Soc Rev, 41 (2012) 2256-2282.

[2] Lévy R, Thanh NT, Doty RC, Hussain I, Nichols RJ, Schiffrin DJ, Brust M, Fernig DG., Am Chem Soc, 126 (2004) 10076-10084.

[3] Morais T, Soares ME, Duarte JA, Soares L, Maia S, Gomes P, Pereira E, Fraga S, Carmo H, Bastos ML, Eur J Pharm Biopharm, 80 (2012) 185-193.

Table 1: Gold distribution (% of the injected dose) in the analyzed rat organs and tissues 30 min or 28 days after i.v. injection of Cit-AuNPs or CALNN-AuNPs. The results are expressed as mean ± standard error (SEM), n=4-5. LQ - Limit of quantification (2.15 ng/mL). -- not assessed * p< 0.05 vs Cit-AuNPs 30 min a p< 0.001 vs Cit-AuNPs 30 min b p< 0.05 vs CALNN-AuNPs 30 min c p< 0.001 vs Cit-AuNPs 30 min d p< 0.001 vs CALNN-AuNPs 30 min

Organ/Tissue

% injected dose

30 min 28 days

Cit-AuNPs CALNN-AuNPs Cit-AuNPs CALNN-AuNPs

Liver 62.92 ± 3.55 52.26 ± 4.48 28.31 ± 3.36a 23.97 ± 3.48b

Spleen 1.21 ± 0,31 2.11 ± 0,30 0.89 ± 0.31 1.00 ± 0.13b

Thymus -- -- <LQ <LQ

Heart 0.52 ± 0.52 0.004 ± 0.003 <LQ <LQ

Lung 0.93 ± 0.70 0.57 ± 0.37 0.03 ± 0.01 0.05 ± 0.03

Kidney 0.008 ± 0.002 0.014 ± 0.002 0.003 ± 0.003 0.01 ± 0.01

Brain <LQ <LQ <LQ <LQ

Skeletal

muscle

<LQ 0.006 ± 0.004 0.01 ± 0.01 <LQ

Small

intestine

0.006 ± 0.004 0.002 ± 0.002 <LQ <LQ

Bone (femur) 0.016 ± 0.004 0.04 ± 0.01 0.08 ± 0.08 0.010 ± 0.004

Testis 0.01 ± 0.01 0.01 ± 0.01 <LQ <LQ

Blood 0.12 ± 0.02 0.05 ± 0.01* <LQ <LQ

Tail 3.34 ± 1.20 6.90 ± 1.36 2.95 ± 0.98 6.64 ± 2.47

TOTAL 68.01 ± 2.99 61.94 ± 3.42 32.27 ± 3.66c 31.69 ± 1.28d


Ricardo Franco1, Miguel A. S. Cavadas1,

Inês Gomes1, Cláudia S. Cunha2, Isabel Silva1, Eulália Pereira3, Diane W. Taylor4, Maria Mota2, Miguel Prudêncio2 1REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal 2Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Portugal 3REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Portugal 4Department of Tropical Medicine, University of Hawaii, Honolulu, U.S.A.

[email protected]

B i o n a n o t e c h n o l o g y f o r M a l a r i a D i a g n o s t i c s : T o w a r d s

a P o i n t - O f - N e e d A s s a y

Despite the fact that several countries were able to eradicate malaria during the past century, it remains one of the most prevalent infectious diseases worldwide. Forty percent of the world’s population is at risk of infection, and 500 million people become infected every year [1]. Hopes for the eradication of this disease during the 20th century were dashed by the ability of Plasmodium falciparum (Pf), its most deadly causative agent, to develop resistance to available drugs. Despite its huge burden, the diagnosis of malaria is often not straightforward. If malaria rapid detection tests (RDT) reliably equal or surpass the efficacy of clinical microscopy, the accepted ‘gold standard’ despite its significant limitations, they could have a significant role in clinical practice [2]. We aim to design a gold nanoparticle (AuNP)-based rapid detection test (RDT) using specific antibodies to detect Plasmodium falciparum (malaria parasite) antigens in clinical specimens. The characteristics of the proposed malaria RDTs include reproducibility, acceptable high sensitivity and specificity, rapidity, ease of performance and interpretation, stability when stored, and capability of species differentiation, all at an affordable price. We recently established the proof-of-concept for a competitive immunofluorescent assay using a Plasmodium falciparum heat shock protein 70 (PfHsp70) antigen/monoclonal antibody pair [3]. This homogeneous assay is based on the fluorescence quenching of cyanine 3B (Cy3B)-labeled recombinant PfHsp70 upon binding to AuNPs functionalized with an anti-PfHsp70

monoclonal antibody (Figure 1). Upon competition with the free antigen, the Cy3B-labeled recombinant PfHsp70 is released to solution resulting in an increase of fluorescence intensity (Figure 2). The estimated LOD for the assay is 2.4 μg.mL−1 and the LOQ is 7.3 μg.mL−1. The fluorescence immunoassay was successfully applied to the detection of antigen in malaria-infected human blood cultures at a 3% parasitemia level, and is assumed to detect parasite densities as low as 1,000 parasites.μL-1. PfHsp70 is nevertheless not the ideal antigen for malaria detection as a protein-sequence similarity search reveals 96-93% identity to other Plasmodium species, and some 80% identity to Coccidian and Cryptosporidiosis parasites. This result indicates that PfHsp70 monoclonal antibody might be unable to distinguish between Plasmodium species, and false positives could be potentially generated by the presence of other prevalent parasitic infections. Plasmodium falciparum histidine-rich protein 2 (PfHRP-2) is a water-soluble protein released from parasitized erythrocytes into in vitro culture supernatants, that has proven to be of interest for its potential effects on the host immune system and as an antigen for specific diagnosis of malaria [4]. We are using a PfHRP-2 antigen/monoclonal antibody pair in the above fluorescent competitive immunoassay format hoping to confirm the validity of the assay and its specificity and sensitivity parameters also for this antigen/monoclonal antibody system. As a drawback for the utilization of this antigen in diagnosis, it has been found that detectable antigen frequently persists after parasite


clearance. The search for new antigens for malaria diagnostics continues, with the aim of revealing more sensitive and disease-specific targets [5]. Acknowledgments: This work was supported by the Luso-American Foundation, Portugal (Grant FLAD-LACR, to RF, DT, MM and MP), and Fundação para a Ciência e a Tecnologia, Portugal (Grants PEst-C/EQB/LA0006/2011 to REQUIMTE; PTDC/CTM-NAN/112241/2009 to RF; and PTDC/SAUMII /099118/2008 to MP). Professor Gregory L. Blatch (Rhodes University, South Africa) and Professor Daniel E. Goldberg (Washington University, USA), are kindly acknowledged for supplying the PfHsp70 and the PfHRP-2 over-expressing plasmids, respectively. References

[1] Silvie O, Mota MM, Matuschewski K, Prudencio

M, Curr Opin Microbiol, 11(4) (2008) 352-359. [2] Murray CK, Bennett JW, Interdiscip Perspect

Infect Dis, 2009 (2009) 415953. [3] Guirgis BS, Sa e Cunha C, Gomes I, Cavadas M,

Silva I, Doria G, Blatch GL, Baptista PV, Pereira E, Azzazy HM, Mota MM, Prudencio M, Franco R, Anal Bioanal Chem, 402(3) (2012) 1019-1027.

[4] Parra ME, Evans CB, Taylor DW, J Clin Microbiol, 29(8) (1991) 1629-1634.

[5] Ray S, Renu D, Srivastava R, Gollapalli K, Taur S, Jhaveri T, Dhali S, Chennareddy S, Potla A, Dikshit JB, Srikanth R, Gogtay N, Thatte U, Patankar S, Srivastava S, PLoS ONE, 7(8) (2012) e41751.

Figures

Figure 1: PfHsp70 detection on saponin-treated pellets of P.

falciparum-infected RBCs of a human blood culture and of RBCs of non-infected human blood. (A) PfHsp70 detection (red bands) following incubation with AuNP-antibody conjugates. (B) PfHsp70 detection by chemiluminescence.

Figure 2: The photoluminescence intensity of Cy3B in the presence of AuNP-antibody conjugates is low due to quenching by the AuNPs (dashed trace). When the PfHsp70 antigen (analyte) binds to the AuNP-antibody conjugates, an increased amount of Cy3B-labeled PfHsp70 is free in solution causing an increase in the photoluminescence intensity (solid trace). Red circles are AuNPs, blue “Y” are antibodies, green diamonds represent the antigen, and pink stars represent the Cy3B label.


P. P. Freitas1,2,3, S. Cardoso1,2, F. A.

Cardoso1,T.Dias1,2, V. C. Martins3, E. Fernandes3,4, C. Carvalho3,4, J. Azeredo3,4, J. P. Amaral1,2, V. Pinto5, R. Ferreira3, E. Paz3, J. Gaspar3, D. Davila3 and J. Noh3 1INESC MN and IST, Lisbon, Portugal 2IST, Physics Department, Lisbon, Portugal 3INL, Braga, Portugal 4Biological Engineering Department, U.Minho, Braga, Portugal 5ICVS, Braga, Portugal

S p i n t r o n i c d e v i c e s f o r b i o m e d i c a l a p p l i c a t i o n s

Spintronic devices have been proposed over the past decade for various biomedical applications. These include static or dynamic biomolecular recognition platforms (DNA-cDNA, antibody-antigen, phage-bacteria, …), cytometer and cell separation devices and lateral bio assay platforms, microelectrode based devices for neuroelectronic applications, and hybrid sensor arrays for imaging applications [1]. The biomolecular recognition platforms include a magnetoresistive sensor array, a set of biomolecular probes (surface immobilized or in solution), biological targets labeled with particular magnetic micro beads or magnetic nanoparticles, and arraying architectures and microfluidics used to increase sensitivity and favour probe-target interaction. The platforms also incorporate the proper signal conditioning and processing electronics. Results will be shown for cell free DNA detection as a cancer marker indicator, and for cell detection using phage markers. For neuroelectronic applications, magnetoresistive sensors were fabricated onto Si microelectrode arrays. Experiments probe either extra cellular currents measured in mouse hypocampus slices, or spinal medulla signals probed directly with implanted

magnetoresistive electrodes. For deep brain simulation and detection, sensors and electrodes are being fabricated into flexible polyimide probes. Separation between straight electrical contributions and magnetic signals is discussed. For imaging applications (magneto cardiography) efforts continue to reach pT level detectivity at 1Hz, using hybrid MEMS/magnetoresistive sensor devices. Two architectures will be presented leading to larger DC field mechanical modulation, and therefore increased sensitivity.

References

[1] “Spintronic platforms for biomedical

applications”, P.P.Freitas, F.a.Cardoso, V.C.Martins, S.A.Martins, J.Loureiro, J.Amaral, R.C.Chavres, S.Cardoso, J.Germano, m.S.Piedade, A.M.Sebastiao, L.F.Fonseca, M.Pannetier-Lecoeur, C.Fermon, Lab Chip,vol. 12(3), pp.546-557, 2012


Rogério Gaspar Faculty of Pharmacy of the University of Lisbon; Avenida Prof. Gama Pinto, 1649-003 Lisboa, Portugal

[email protected]

N a n o m e d i c i n e s : t h e c l i n i c a l u s e a n d t h e c h a l l e n g e s c o m i n g

f r o m n e w m a n u f a c t u r i n g s c i e n c e a n d h e a l t h c a r e c o s t s

The increased complexity of factors involved in drug discovery, design, development and usage (3DU) makes way for new approaches that can integrate Science & Technology serving the needs of patients. Among those approaches the need to establish more efficient strategies to transform Science in better Healthcare faces challenges from Industrial organization (and business model), from Science gaps (in certain areas evident lack of adequate models for translation to first in man or clinical trials) and from non-harmonized views in certain areas between regulators and scientists.

Systems approaches will become more common through the introduction of complex analytical and predictive tools, by opening new doors for systems toxicology (allowing room for the introduction of modern toxicology methods), systems pharmacology (a whole new paradigm currently addressed by a number of NIH initiatives), systems therapeutics (integrating also pharmacoepidemiology and pharmacogenetics, as well as efficacy and effective evaluation tools, paving the way for health technologies assessment with a better scientific base), systems technologies (Quality by Design or QbD approaches, through the use of PAT), and complex systems, through the development and use of new hybrid and increasingly complex structures that will allow to combine different therapeutic targets with a combination of diagnostics, therapeutics and monitoring. These five systems approaches are the Science base for modern Regulatory Science.

All advances need to be put in the context of improved healthcare, more efficient, with increased rationale use of complex therapeutic platforms, optimizing diagnostic and therapeutic functions, delivering affordable technologies capable of really improving healthcare in specific groups or populations of patients.

Health technology assessment (HTA) will bring to the table the need to integrate medicines and diagnostics, including better biomarkers for both

safety and efficacy, including the use of new imaging techniques together with new purposely engineered materials platforms.

Drug usage based in science approaches making use of Pharmacoepidemiology and/or Pharmacogenetics as well as improved communication skills from health professionals, will be increasingly a key-point in the rationale use of medicines in the context of the overall rational use of healthcare technologies. After 3 decades of clinical experience, more than 40 nanomedicines now in the market have consolidated the area as a major player for health improvement. Nanomedicine is now in a head position to solve some of these issues regarding increased complexity of systems and affordable technologies for healthcare, providing solutions for the integration of diagnostics and therapeutics

References

[1] R Gaspar, B Aksu, A Cuine, M Danhof, M

Jadrijevic-Mladar Takac, HH Linden, A Link, E-M Muchitsch, CG Wilson, P Öhrngren, L Dencker - Towards a European Strategy for Medicines Research (2014-2020): The EUFEPS Position Paper on Horizon 2020. European Journal of Pharmaceutical Sciences (2012) 47 (2012) 979–987

[2] R Duncan and R Gaspar - Nanomedicine(s) under the microscope, Molecular Pharmaceutics (2011) 8(6): 2101-2141


J. Glückstad, A. Bañas, T. Aabo and D. Palima DTU Fotonik, Dept. of Photonics Engineering, Technical University of Denmark, Ørsted Plads 343, 032 DK-2800 Kgs. Lyngby, Denmark

[email protected] www.ppo.dk www.optorobotix.com

S t r u c t u r e - m e d i a t e d n a n o s c o p y

The science fiction inspired shrinking of macro-scale robotic manipulation and handling down to the micro- and nano-scale regime open new doors for exploiting the forces and torques of light for micro- and nanobiologic probing, actuation and control [1]. Advancing light-driven micro-robotics requires the optimization of optical forces and torques that, in turn, requires optimization of the underlying light-matter interaction. The requirement of having tightly focused beams in optical tweezing systems exemplifies the need for optimal light-shaping in optical trapping, manipulation and sorting [2]. On the other hand, the recent report on stable optical lift shows that optical manipulation can be achieved, even when using unshaped light, by using an appropriately shaped structure instead [3]. Therefore, a generic approach for optimizing light-matter interaction would involve the combination of optimal light-sculpting techniques [4] with the use of optimized shapes in micro-robotics structures [5]. Micro-fabrication processes such as two-photon photo-polymerization offer three-dimensional resolutions for creating custom-designed monolithic microstructures that can be equipped with optical trapping handles for convenient mechanical control using only optical forces [6]. These microstructures can be effectively handled with simultaneous top- and side-view on our BioPhotonics Workstation to carry out proof-of-principle experiments illustrating the six-degree-of-freedom optical actuation of two-photon polymerised microstructures equipped with features easily entering the submicron-regime. Furthermore, we exploited the light shaping capabilities available on the BioPhotonics Workstation to demonstrate a new strategy for controlling microstructures that goes beyond the typical refractive light deflections that are utilized in conventional optical trapping and manipulation. We took this approach to extend the opto-mechanical light-force driven capabilities by including functionalised mechanisms to the fabricated

monolithic structures. Aided by collaborators who fabricated test structures with built-in waveguides for us, we were able to put the idea of optically steerable freestanding waveguides – coined: wave-guided optical waveguides - to the test using our BioPhotonics Workstation [7]. We also proposed designing micro-structures for so-called structure-mediated access to the nanoscale and real-time sculpted light for the strongly emerging areas of neurophotonics and optogenetics.

References

[1] P. Rodrigo, L. Kelemen, D. Palima, C. Alonzo, P. Ormos, and J. Glückstad, "Optical microassembly platform for constructing reconfigurable microenvironments for biomedical studies," Optics Express 17, 6578-6583 (2009).

[2] J. Glückstad, “Sorting particles with light,” Nature Materials 3, 9-10 (2004).

[3] J. Glückstad, “Optical manipulation: Sculpting the object,” Nature Photonics 5, 7-8 (2011).

[4] E. Papagiakoumou, F. Anselmi, A. Begue, V. de Sars, J. Glückstad, E. Isacoff, V. Emiliani, “Scanless two-photon excitation of channelrhodopsin-2,” Nature Methods 7, 848-854 (2010).

[5] D. Palima, A. R. Bañas, G. Vizsnyiczai, L. Kelemen, P. Ormos, and J. Glückstad, "Wave-guided optical waveguides," Opt. Express 20, 2004-2014 (2012).

[6] D. Palima and J. Glückstad, “Gearing up for optical microrobotic manipulation: mechanical actuation of synthetic microstructures by optical forces,” Laser & Photonics Reviews (upcoming) (2012).

[7] H. Ulriksen, J. Thøgersen, S. Keiding, I. Perch-Nielsen, J. Dam, D. Palima, H. Stapelfeldt, and J. Glückstad, "Independent trapping, manipulation and characterization by an all-optical biophotonics workstation," J. Eur. Opt. Soc-Rapid 3, 08034 (2008).


Figures

Figure 1: Structure-mediating tool for nanoscopic probing, analysis and excitation. Adapted from reference [5].


Peter Gnauck, Danielle Elsiwck, Mohan Ananth, Lewis Stern, John Notte, Larry Scipioni, Chuong Huynh, David Ferranti Carl Zeiss Microscopy, Carl Zeiss Str. 56, Oberkochen, Germany

[email protected]

H e l i u m I o n M i c r o s c o p y . E x t e n d i n g t h e f r o n t i e r s o f

n a n o t e c h n o l o g y

The Helium Ion Microscope has been described as an impact technology offering new insights into the structure and function of nanomaterials [1]. Combining a high brightness Gas Field Ion Source (GFIS) with unique sample interaction dynamics, the helium ion microscope provides images offering unique contrast and complementary information to existing charged particle imaging instruments such as the SEM and TEM [2]. Formed by a single atom at the emitter tip, the helium probe can be focused to below 0.25nm offering the highest recorded resolution for secondary electron images. The small interaction volume between the helium beam and the sample also results in images with stunning surface detail . Besides imaging, the helium ion beam can be used for fabricating nanostructures at the sub-10nm length scale. Researchers have used the helium ion beam for exposing resist and features as small as 4nm have been reported [3]. The main advantage of helium ion lithography over electron beam lithography is the minimal proximity effect [Fig 2, 3]. The helium ion beam has also been used for deposition and etching in conjunction with appropriate chemistries [4]. Helium induced deposition results in higher quality deposits than with Ga-FIB or EBID (Electron Beam Induced Deposition). Finally, the helium ion beam can be used for direct sputtering of different materials. Patterning of graphene has resulted in 5nm wide nanoribbons [Fig.1] and 3.5nm holes in silicon nitride membranes have been demonstrated. However, due to its lower mass, the helium sputter rate is significantly lower than with gallium. Further, helium tends to implant rather than sputter silicon which is an issue for FIB applications in semiconductors. To overcome these issues, we have developed the GFIS to operate with Ne.

The Gas Field Ion Source has been modified and the gun redesigned to allow the use of both He and Ne source gases. Although Best Imaging Voltage (BIV), defined as the optimal voltage to get the highest source brightness, is lower for Ne, the system is optimized to operate under the same column conditions for both gases. The neon probe size is greater than helium and is measured between 1-2nm although additional improvements are expected. However this is not a limitation from a nanofabrication standpoint. The sputter yield of Ne is about 30X higher than He, and the Ne beam has a shallower penetration depth resulting in lower sub-surface damage. The sputtering of materials with Ne is significantly better than He and generally within a factor 2X of Ga. Neon ion beam has been used for Lithography and is shown to be 1000X more efficient than 30keV electron beam with the ability to print 7nm lines [5]. This work has culminated in the development of an ion microscope with a gas field ion source that can operate with both He and Ne. References

[1] Smentkowski, V.S., Denault, L., Wark, D.,

Scipioni, L., and Ferranti, D, Microscopy and Microanalysis 16(Suppl.2), (2010) p.434

[2] Bell, D. C., Microscopy and Microanalysis 15, (2009), p.147

[3] Li, W., Wu, W., and Williams, R.S., SPIE Lithography Conference (2012)

[4] Sanford, C.A., Stern, L., Barriss, L., Farkas, L., DiManna, M., Mello, R., Maas, D.J., Alkemade, P.F.A., J. Vac. Sci. Technol. B 27(6), (Nov/Dec 2009), p.2660

[5] Winston, D., Manfrinato, V.R., Nicaise S.M., Cheong, L.L., Duan, H., Ferranti, D., Marshman, J., McVey, S., Stern, L., Notte, J., Berggren, K.K., Nano Letters 11(10), (2011), p.4343


Figures

Figure 1: Nanoribbons in Graphene; (Results courtesy of Dan Pickard NUS).

Figure 2: SEM suffers from proximity effects: Exposed dots near the center are much bigger than the same exposed dots at the corners. (Results courtesy of Karl Bergren of MIT)

Figure 3: When exposed with a helium beam, the exposed region is smaller, AND more consistent – independent of nearby exposures. (Results courtesy of Karl Bergren of MIT)


J. Gomes1,2, C. Guerreiro3, R. Miranda3,

P. Carvalho4 1Área Departamental de Engenharia Química, ISEL – Instituto Politécnico de Lisboa, Portugal 2IBB – Instituto Superior Técnico – Universidade Técnica de Lisboa, Portugal 3UNIDEMI, Departamento de Engenharia Mecânica e Industrial, Universidade Nova de Lisboa, Portugal 4ICEMS, Departamento de Bioengenharia, Instituto Superior Técnico – Universidade Técnica de Lisboa, Portugal

[email protected]

A s s e s s m e n t o f n a n o p a r t i c l e s e m i s s i o n s r e s u l t i n g f r o m a r c

w e l d i n g o f m i l d s t e e l

Welding is the principal industrial process used for joining metals. However, it can produce dangerous fumes that may be hazardous to the welder’s health and it is estimated that, presently, 1-2% of workers from different professional backgrounds (which accounts for more than 3 million persons) are subjected to welding fume and gas action. With the advent of new types of welding procedures and consumables, the number of welders exposed to welding fumes is growing constantly in spite of the mechanization and automation of the processes. Simultaneously, the number of publications on epidemiologic studies and the devices for welders’ protection is also increasing. Apart from that, the influence of very ultrafine particulate, lying in the nanoparticles range, on human health has been pointed to be of much concern as airborne nanoparticles are resulting both from nanotechnologies processes and also from macroscopic common industrial processes such as welding. In fact, nanotoxicological research is still in its infancy and the issuing and implementation of standards for appropriate safety control systems can still take several years. Yet, the advanced understanding of toxicological phenomena on the nanometer scale is largely dependent on technological innovations and scientific results stemming from enhanced R&D. Meanwhile, the industry has to adopt proactive risk management strategies in order to provide a safe working environment for their staff, clients and customers, and obtain products without posing health threats at any point of their lifecycle. Understanding the relationship of airborne nano sized particulate and human health, under different environmental conditions is of great importance for improving

exposure estimates and for developing efficient control strategies to reduce human exposure and health risk and for establishing, evaluating and improving regulations and legislation both on air quality, airborne emissions and the incorporation of nano sized materials in other products and commodities [1].

The fusion welding processes generate fumes that contain nanoparticles, however it is not known a relationship between the welding parameters and the emitted nanoparticles. From the most common welding processes in the industry there are two more widespread, the shielded metal arc and the active metal arc welding. Therefore it is important to study these two processes. The main objectives of this study were the analyses of released particles from this processes, the characterization of the particles by concentration and composition and the correlation between the operating conditions of the welding processes. Welding tests were performed using different welding parameters, quantifying nanoparticle emissions. Nanoparticles were also collected and characterized by transmission electronic microscopy. In this study, which covered two welding processes Shielded Metal Arc Welding (SMAW) and (Metal Active Gas) MAG, it was possible to determine the existence of nanoparticles having a high deposition rate in the alveolar tract, possibly causing a decrease on the respiratory capacity of welders as other technical personal involved in welding operations. Studies such as this enable the determination of the alveolar surface area of nanoparticles deposited, concentration, morphology and composition resulting from various process conditions.


With this aim, a Nanoparticle Surface Area Monitor, TSI3550, was used for assessing exposure to nano particles produced and manipulated in laboratory and industrial facilities. This equipment indicates the human lung-deposited surface area of particles expressed as square micrometers per cubic centimeter of air (μm2/cm3), corresponding to tracheobronchial (TB) and alveolar (A) regions of the lung. Also, granulometry of particles was measured in the nano range using a Scanning Mobility Particle Size Spectrometer, TSI3034. Particles were sampled using a Nanometer Sampler Analyser, TSI3089 and observed further on using scanning electronic microscopy.

The obtained results clearly demonstrated the existence of airborne nanoparticles, as shown in figures 1 and 2, in the analyzed welding processes [2-4].

References

[1] M. Shalom, J. Albero, Z. Tachan, E. Martinez-

Ferrero, A. Zaban, E. Palomares, The Journal of Physical Chemical Letters, 1 (2010), 1134.

[2] K. Tvrdy, P.A. Frantsuzov, P.V. Kamat, PNAS, 108, (2010), 29.

[3] B. Wang, L.L. Kerr, Solar Energy Materials & Solar Cells, 95 (2011), 2531.

[4] K. Fan, T. Peng, J. Chen, X. Zhang, R. Li, Journal of Materials Chemistry, 22 (2012), 16121.

[5] L. Hu, J.W. Choi, Y. Yang, S. Jeong, F. La Manti, L.-F. Cui, Y. Cui, PNAS, 51 (2009), 21490.

[6] S.A. Aromal, D. Philip, Physica E, 44 (2012), 1692.

[7] D. Tsukamoto,Y. Shiraishi, Y. Sugano, S. Ichikawa, S. Tanaka, T. Hirai, Journal of the American Chemical Society, 134 (2012), 6309.

[8] A. Higazy, M. Hashem, A. ElShafei, N. Shaker, M.A. Hady, Carbohydrate Polymers, 4 (2010), 890.

Figures

Figure 1: TEM image of nanoparticles resulting from arc welding of mild steel using gaseous mixture Ar+ 18% CO2 in globular transfer mode

Figure 2: Size distribution of nanoparticles resulting from arc welding of mild steel using gaseous mixture Ar+8% CO2 in globular transfer mode


J. W. González, F. Delgado, and J. Fernández-Rossier International Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga, 4715-330 Braga, Portugal

[email protected]

G r a p h e n e s i n g l e e l e c t r o n t r a n s i s t o r a s a s e n s o r f o r

m a g n e t i c m o l e c u l e s

Graphene is a very promising candidate for high precision molecular sensing, due to its extremely large surface to volume ratio, and its electrically tunable large conductivity [1]. On the other hand, being a zero-gap semiconductor with small mass and small density of spinfull nuclei, makes graphene a material with potentially large spin lifetime both, for carriers and host magnetic dopants [2].

Taken together, these two ideas naturally lead to the use of graphene as a detector of the spin state of extrinsic magnetic centers, in the form of magnetic ad-atoms, vacancies and spinfull molecules. This connects with recently reported [3, 4] experiments in which gated graphene nanoconstrictions, operating in the single electron transport (SET) regime, showed hysteric behavior in the linear conductance when a magnetic field is ramped.

In this work we provide a theoretical background to understand how the magnetic state of localized magnetic moments affects transport through the graphene nanoconstriction in the SET regime. We consider transport across a spin-split state [5]. In our system, the energy splitting arises from the exchange coupling to the extrinsic magnetic centers. This spiting effectively gates the nanoconstriction, changing its conductance thereby. We model the graphene nanoconstriction decorated with magnetic centers with a random exchange field tight binding Hamiltonian that we solve numerically. We discuss the experimental conditions, such as temperature, density of magnetic centers, exchange coupling strength, tunnel rate, under which the graphene nanoconstriction can operate an efficient spin sensor.

We also compare our modeling with the experimental results [6].

References

[1] F. Schedin, A. Geim, S. Morozov, E. Hill, P. Blake,

M. Katsnelson, and K. Novoselov, Nature Materials 6, 652 (2007).

[2] D. Pesin and A. MacDonald, Nature Materials 11, 409(2012).

[3] A. Candini, S. Klyatskaya, M. Ruben, W. Wernsdorfer, and M. Affronte, Nano Letters 11, 2634 (2011).

[4] M. Urdampilleta, S. Klyatskaya, J. Cleuziou, M. Ruben, and W. Wernsdorfer, Nature Materials 10, 502 (2011).

[5] P. Recher, E. Sukhorukov, and D. Loss, Phys. Rev. Lett. 85, 1962 (2000).

[6] J. W. González, F. Delgado, and J. Fernández-Rossier, In preparation.

Figures

Figure 1: (a) Scheme of a graphene constriction with randomly distributed magnetic centers. (b) Diagram with the system energy levels and graphene density of states.


Luis E. Hueso, Marco Gobbi, Amilcar Bedoya-Pinto, Federico Golmar, Felix Casanova CIC nanoGUNE, San Sebastian, Spain IKERBASQUE, Basque Foundation for Science, Spain

[email protected]

S p i n t r o n i c d e v i c e s w i t h f u l l e r e n e s

Organic and carbon-based materials have recently caught the attention of spintronics, and significant efforts are being made towards their integration in this field [1,2]. One of their most attractive aspect for spintronic applications is the weakness of their spin scattering mechanisms, implying that the spin polarization of the carriers can be maintained for a very long time in these materials. Noticeably, spin relaxation times of microseconds have been reported by different techniques, with values exceeding by orders of magnitude the characteristic times detected in inorganic materials. Moreover, these materials might have tunable chemical properties, opening a way for the integration of synthetic chemistry into spintronic devices.

In this talk I shall focus on different spintronic devices with C60 fullerenes. In the first part, I will show how C60 acts as a spacer in hybrid ferromagnetic/organic spin valves [3]. I will present room temperature magnetoresistance data that consistent with a multistep tunneling regime.

In the second part I will introduce a magnetic tunnel transistor with C60 as a collector [4]. In this device, hot-electron magnetoconductance values of up to 90% at room temperature have been recorded. Moreover, this magnetoconductance can be increased to any arbitrarily high value by suppressing the non-spin polarized current flowing in the device

References

[1] L.E. Hueso et al., Nature 445 (2007) 410 [2] V. Dediu, L.E. Hueso et al., Nature Materials 8

(2009) 707 [3] M. Gobbi, et al., Advanced Materials 23 (2011)

1609 [4] M. Gobbi, et al., Applied Physics Letters 101

(2012) 102404


A. Kasumov1, A.D. Chepelianskii1,2, D

Klinov3, S Guґeron1, O Pietrement4, S Lyonnais5 and H Bouchiat1 1LPS, Univ. Paris-Sud, CNRS, France 2Cavendish Laboratory, University of Cambridge, UK 3Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Russia 4UMR 8126 CNRS-IGR-UPS, Institut Gustave-Roussy, France 5Museum National dHistoire Naturelle, CNRS, France

[email protected]

L o n g r a n g e e l e c t r o n i c t r a n p o r t i n D N A m o l e c u l e s

We report our experiments on the conduction of λ DNA molecules over a wide range of temperature deposited across slits in a few nanometers thick platinum film. These insulating slids were fabricated using focused ion beam etching and characterized extensively using near field and electron microscopy [1]. This characterization revealed the presence of metallic Ga nanoparticles inside the slits, as a result of the ion etching. After deposition of λ DNA molecules, using a protocol that we describe in detail, some of the slits became conducting and exhibited superconducting fluctuations at low temperatures. We argue that the observed conduction was due to transport along DNA molecules, that interacted with the Ga nanoparticles present in the slit. At low temperatures when Ga becomes superconducting, induced superconductivity could therefore be observed. These results indicate that minute metallic particles can easily transfer charge carriers to attached DNA molecules and provide a possible reconciliation between apparently contradictory previous experimental results concerning the length over which DNA molecules can conduct electricity.

On four samples superconductivity was observed whereas a last resistive sample had a differential conductance similar to grapheme (Fig.1). Due to high critical magnetic fields around 10 Tesla we interpreted the observed superconductivity as proximity effect from superconducting nanoparticles inside the FIB slit. On a control sample where a short circuit was formed by stopping FIB etching before the sample became insulating no superconductivity was observed. In order to search for sample characteristics which might be specific of DNA molecules we have irradiated our samples with

microwaves. Our idea was that the helix structure of the molecule could induce special magnetic field asymmetry in the out of equilibrium transport across the molecule. This expectation was not confirmed experimentally since the R(B) dependence under irradiation remained rather symmetrical. However the DC-magnetoresistance of our samples could become unstable under microwave irradiation (see Fig. 2). Interestingly instabilities were observed mainly at rather low frequencies f < 1 GHz. A possible (although science fiction like) interpretation is that the microwave field excites a mechanical transition between two possible equilibrium positions for a DNA molecule suspended across the peaks created on both sides of the gap by the FIB etching; in this scenario the superconductivity just enhances the sensibility to these mechanical vibrations. However one must take into account that the response to microwave may be very complicated in superconducting weak links where the switching may become chaotic. In particular magnetic field anti-symmetric photovoltaic effect was observed in such systems by [2]. Hence the presence of a magnetic field asymmetry does not allow to discriminate between a chiral molecule like DNA and an array of superconducting weak links.

Several arguments can be retained to demonstrate that long range transport across DNA molecules was observed in our experiments. The first argument is statistical, for transport was not observed after deposition of a buffer solution without DNA. However one must be cautious with statistical arguments in these systems where sample to sample fluctuations are large. The destruction of conductance by UV irradiation with wavelength 233


nm is in this sense more convincing since UV are unlikely to destroy metallic nano-filaments. However the experiment was performed on only a single sample and more statistics and better control of irradiation doses are needed. Concerning the conduction data the observed proximity effect suggests that transport takes place across a nanowire with a very small density of states. It is tempting to conclude from this argument that transport indeed takes place along DNA molecules.

References

[1] A.D. Chepelianskii, D. Klinov, A. Kasumov, S.

Guron, O. Pietrement, S. Lyonnais and H. Bouchiat, New J. Phys. 13 (2011) 063046.

[2] R. E. Bartolo and N. Giordano, Phys. Rev. B 54 (1996) 3571.

Figures

Figure 1: The panels a,b,c. show the differential resistance of the 3 kΩ, 4.8 kΩ and 6.1 kΩ samples which have a superconducting behavior. The panel d. displays the differential conductance of the resistive 10 MΩ sample. Temperature was 100 mK.

Figure 2: Magnetoresistance of the 10 kΩ sample at T = 1.3K, i = 10nA for several microwave powers. Microwave frequency was f = 298 MHz.


Brian A. Korgel, Aaron Chockla, Tim Bogart, Xiaotang Lu The University of Texas at Austin, Department of Chemical Engineering, Austin, TX USA

[email protected]

S i l i c o n a n d G e r m a n i u m N a n o w i r e s f o r N e x t

G e n e r a t i o n H i g h C a p a c i t y L i t h i u m I o n B a t t e r i e s

Lithium (Li)-ion batteries have the highest energy and power density of any available rechargeable battery technology and they are widely used to power portable electronics. Nonetheless, Li-ion batteries are needed with much lower cost, lighter weight, higher energy density, and better performance at fast charge/discharge rates. One way to increase the energy density of a Li-ion battery is to replace the graphite anode with silicon (Si) or germanium (Ge). Si and Ge have significantly higher lithium storage capacities than graphite (3,579 mA h g-1 and 1,384 mA h g-1 compared to 373 mA h g-1), however, they undergo massive volume expansions when lithiated—by about 280%. Nanowires might be able to tolerate these volume changes without degradation. Here, we present the latest battery results from our laboratory using large quantities of Si and Ge nanowires grown by solution-based methods [1-4]. Battery performance depends on all of the constituents of the anode, including electrolyte and binder formulations, and even the seeds used to grow the nanowires. The highest performance Si nanowires have been grown using tin seeds, which is also electrochemically active, and Ge nanowires have exhibited the best rate capability with capacities near the theoretical capacity due to its reasonably high electrical conductivity and fast Li diffusion.

References

[1] A. M. Chockla, K. C. Klavetter, C. B. Mullins, B. A.

Korgel, “Tin-Seeded Silicon Nanowires for High Capacity Li-ion Batteries,” Chem. Mater., 24 (2012) 3738-3745.

[2] A. M. Chockla, K. Klavetter, C. B. Mullins, B. A. Korgel, “Solution-Grown Germanium Nanowire Anodes for Lithium-Ion Batteries,” ACS Appl. Mater. & Interfaces, 4 (2012) 4658-4664.

[3] A. M. Chockla, T. D. Bogart, C. M. Hessel, K. Klavetter, C. B. Mullins, B. A. Korgel, “Influences of Gold, Binder and Electrolyte on Silicon Nanowire Performance in Li-Ion Batteries,” J. Phys. Chem. C, 116 (2012) 18079-18086.

[4] A. M. Chockla, J. T. Harris, V. A. Akhavan, T. D. Bogart, V. C. Holmberg, C. Steinhagen, C. B. Mullins, K. J. Stevenson, B. A. Korgel, “Silicon Nanowire Fabric as a Lithium Ion Battery Electrode,” J. Am. Chem. Soc., 133 (2011) 20914-20921.


I. A. Larkin and O. G. Balev Department of Physics, Minho University, Braga 4710-057, Portugal

[email protected]

E d g e m a g n e t o p l a s m o n s i n s t r o n g l y n o n - u n i f o r m

m a g n e t i c f i e l d

We have theoretically studied two-dimensional electron gas (2DEG) placed in a strong laterally non-uniform magnetic field, which appears due to ferromagnetic film (Fig 1.). We have found, that in this case 2DEG experiences static charge redistribution that strongly depends on presence and configuration of the gates on the surface of a heterostructure [1].

Also, it is shown that lateral inhomogeneity of a strong magnetic field allows itself “magnetic gradient” or “magnetic-edge” magnetoplasmons due to complex lateral structure of magnetic field gradient. This mechanism is different from usual “density gradient” edge magnetoplasmons [2, 3]. We have investigated two families of different-chirality modes localized near the edge of the magnetic film. They are characterized by different direction of magnetoplasmon propagation that determined by sign of the gradient of magnetic field (Fig. 2). Spectrum of plasmons is sensitive to surface of heterostructure preparation. We have analyzed in detail influence of the electrostatic boundary conditions near the edge of metal gate. We have found, that gate always screens out long range coulomb interaction and kernel of the integral equation that determine dispersion of magnetoplasmons remains finite. Therefore, contrary to the previous findings [2,3] none of the fundamental state has logarithmically large phase velocity at small wave vectors. References

[1] I. A. Larkin, J. H. Davies, Phys. Rev. B 52, 5535,

(1995). [2] I. L. Aleiner, L. I. Glazman Phys. Rev. Lett. 72,

2935 (1994) [3] O. G. Balev and P. Vasilopoulos, Phys. Rev. Lett.

81, 1481 (1998)

Figures

Figure 1: Heterostructure layout and profile of the magnetic induction at edge of the ferromagnetic film in perpendicular external field.

Figure 2: Gradient of inverse magnetic field dB-1(y)/dy (thick brown curve) at external field at H = 1.2 Tesla and magnetic induction of ferromagnetic film B = 0.6 Tesla. Blue curve shows shape of fundamental mode localized at minimum of gradient at the edge of the gate, red curve shows the shape of fundamental mode under exposed surface and orange curve slowest fundamental mode localized under the gate. Figures near curves show phase velocities of these modes.


A. Califórnia1, A. Pinto1, N. M. Santos1, J.

F. Silva1, J. G. Rocha2, M. G. Santos3, L. Pereira3 and J. Gomes1 1CeNTI – Centre for Nanotechnology and Smart Materials, Portugal 2University of Minho, Department of Industrial Electronics, Portugal 3Organic Semiconductors Laboratory, Department of Physics and i3N – Institute of Nanostructures, Nanomodelling and Nanofabrication, University of Aveiro, Portugal

[email protected]

T r a n s p a r e n t t h i n f i l m s f o r T C O s r e p l a c e m e n t – A R o l l - t o -

R o l l a p p r o a c h

Traditionally, doped metal oxides have the most widespread use for various applications requiring a transparent conductor. These materials have been well researched and refined during the last fifty years. Over the time, applications changed toward more electronic device fabrication and more advanced techniques became available in order to produce thin films composed by metal oxides. Conductive polymers, the organic analog to metal oxides, have a technical genealogy traceable to the 1970s with the discovery of polyacetylene. New conductive polymers were posteriorly discovered as PEDOT:PSS but the low conductivity obtained has lead to develop more studies in order to improve it [1].

Doped metal oxides and conductivity polymer material classes, dominated the 20th century with metal oxides as the most technically advanced and utilized material. At the beginning of 21th century, rapid advances in nanomaterials have brought about interesting, emerging material alternatives, which will challenge ITO’s dominance in traditional applications, and open up possibilities for new applications [1].

With new emerging materials, the possibility of use different techniques to process thin films becomes extremely promising. One of the most important options are the techniques that apply a printing or coating procedure, capable of being used as a continue process like roll-to-roll technique, thus lowering the prices of the built devices. A range of examples could be found on literature related with the analysis of low cost processes in the production of organic electronic devices as organic photovoltaic’s (OPV’s) [2].

In this work there is the evaluation of the possibility to apply techniques such as Screen Printing and Slot-Die to process a hybrid film using PEDOT:PSS and Silver, in order to understand the influence of the silver pattern and the respective lines width on the equivalent resistance of a thin film. In addition, studies will be carried out related with the morphology and the percentage of light that crosses the hybrid film.

References

[1] David S. Hetch et al, Advanced Materials, 23

(2011) 1482-1513. [2] Nieves Espinosa, Frederick C. Krebs et al, Solar

Energy Materials & Solar Cells, 97 (2012) 3-13


Craig J. Medforth1, Ana Gomes1, Joana

Marques1, Daniela Rodrigues1, Pedro Quaresma1, John A. Shelnutt2, Yongmin Tian2, Lin Jiang3 and Hong Wang3 1REQUIMTE/Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal [email protected] 2Center for Integrated Nanotechnologies, P.O. Box 5800, MS1315, Albuquerque, NM 87185-1315, USA 3Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA

[email protected]

N e w I n s i g h t s i n t o t h e S y n t h e s i s a n d S t r u c t u r e s o f

S e l f - A s s e m b l e d P o r p h y r i n N a n o m a t e r i a l s

Recent studies have shown that self-assembly of porphyrins is a powerful method for the production of highly functional nanomaterials [1]. Porphyrin-based nanomaterials can be synthesized by a range of methods including ionic self-assembly (ISA), re-precipitation and coordination polymerization. ISA of oppositely-charged water-soluble porphyrins is particularly promising because of the potential to couple porphyrins to produce novel materials with unusual properties. This methodology has been used to prepare binary catalytic nanoscale materials at liquid-liquid interfaces [2], on templates [3], or spontaneously in solution [1,4,5]. These binary materials have numerous potential applications in optoelectronics, catalysis and alternative energy and have been successfully used as light-harvesting photocatalysts for reduction of H2O to H2 [6], as selective electrocatalysts for reduction of O2 to H2O [2], as adsorbed pigments for functionalizing carbon nanotubes [7], as H2 storage materials [8], and as photoconductors [4].

This talk will describe advances in the preparation of porphyrin nanomaterials by ionic self-assembly of oppositely-charged porphyrins in aqueous solutions. The first study concerns the stoichiometry of the porphyrins in nanomaterials prepared by ISA. In all cases reported in the literature, the stoichiometry of the porphyrin anions and cations in the nanomaterials is a function of the charges of the porphyrin ions in solution. For example, tetraanionic and tetracationic porphyrins produce a 1:1 solid, whereas dianionic and tetacationic porphyrins produce a 2:1 solid. Recently, we discovered the first example of an ionic solid which does not conform to this rule. Mixing equimolar amounts of H4TPPS2-

and SnTAPP4+ (see Figure) produces a 1:1 rather than the expected 2:1 solid. Addition of a second equivalent of H4TPPS2- converts the 1:1 to the 2:1 solid. The origins of the unusual behavior of the H4TPPS2-/SnTAPP4+ system and its potential applications in the preparation of novel porphyrin nanomaterials by ISA are discussed. A second area of research involves advancing the ionic self-assembly method beyond synthetic porphyrins based on the standard TPP framework (Figure). Porphyrins with extended π-systems or nonplanar structures are known to have significantly altered optical and electronic properties and may be useful in tuning the properties of binary nanostructures for specific applications. Investigations of the ISA of H4TPPS2- with the highly nonplanar π-extended porphyrin NiOPyTBz8+ (Figure) [9] are described. Finally, preliminary results on the preparation of chiral binary porphyrin nanostructures via ISA are presented. It is known that physical forces such as stirring can induce the formation of chiral self-aggregates in solutions of H4TPPS2- even though H4TPPS2- is an achiral molecule [10]. Reversal of the direction of stirring results in a reversal of the chirality of the aggregates. The reaction of H4TPPS2- and SnTPyP4+ has previously been shown to produce nanotubes (Figure) [11]. The effect of stirring on the structures and optical properties of the nanomaterials produced by this reaction is described.

The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° PCOFUND-GA-2009-246542 and


from the Foundation for Science and Technology of Portugal. C.J.M. is the recipient of a Marie Curie Fellowship from the Fundação para a Ciência e a Tecnologia, Portugal and the Marie Curie Action Cofund. References

[1] For a review see: Medforth, C. J.; Wang, Z.;

Martin, K. E.; Song, Y.; Jacobsen, J. L.; Shelnutt, J. A. Chem. Commun. (2009) 7261.

[2] Olaya, A. J.; Schaming, D.; Brevet, P.-F.; Nagatani, H.; Zimmermann, T.; Vanicek, J.; Xu, H.-J.; Gros, C. P.; Barbe, J.-M.; Girault, H. H. J. Am. Chem. Soc. 134 (2012) 498.

[3] Lauceri, R.; Fasciglione, G. F.; D'Urso, A.; Marini, S.; Purrello, R.; Coletta, M. J. Am. Chem. Soc. 130 (2008) 10476.

[4] Martin, K. E.; Wang, Z.; Busani, T.; Garcia, R. M.; Chen, Z.; Jiang, Y.; Song, Y.; Jacobsen, J. L.; Vu, T. T.; Schore, N. E.; Swartzentruber, B. S.; Medforth, C. J.; Shelnutt, J. A. J. Am. Chem. Soc. 132 (2010) 8194.

[5] Tian, Y.; Beavers, C. M.; Busani, T.; Martin, K. E.; Jacobsen, J. L.; Mercado, B. Q.; Swartzentruber, B. S.; van Swol, F.; Medforth, C. J.; Shelnutt, J. A. Nanoscale 4 (2012) 1695.

[6] Tian, Y.; Martin, K. E.; Shelnutt, J. Y.-T.; Evans, L.; Busani, T.; Miller, J. E.; Medforth, C. J.; Shelnutt, J. A. Chem. Commun. 47 (2011) 6069

[7] Brewer, A.; Lacey, M.; Owen, J. R.; Nandhakumar, I.; Stulz, E. J. Porphyrins Phthalocyanines 15 (2011) 257.

[8] Oztek, M. T.; Hampton, M. D.; Slattery, D. K.; Loucks, S. Int. J. Hydrogen Energy 36 (2011) 6705.

[9] Jiang, L.; Zaenglein, R. A.; Engle, J. T.; Mittal, C.; Hartley, C. S.; Ziegler, C. J.; Wang, H. Chem. Commun. 48 (2012) 6927.

[10] For a review see: Crusats, J.; El-Hachemi, Z.; Ribo, J. M. Chem. Soc. Rev. 39 (2010) 569.

[11] Wang, Z.; Medforth, C. J.; Shelnutt, J. A. J. Am. Chem. Soc. 126 (2004) 15954.

Figures

Figure 1

90 nm

70


Manuel Melle-Franco Centro de Ciências e Tecnologias de Computação, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal

[email protected]

R e a l i s t i c m o d e l i n g o f c a r b o n n a n o s t r u c t u r e s , b r i d g i n g t h e

g a p b e t w e e n t h e o r y a n d e x p e r i m e n t

Computer simulation has played a determinant role in the explosive development of carbon nanotechnology by predicting and explaining novel electronic properties in carbon nanomaterials. In recent years (and in a more modest scale) we have used and developed different quantum chemical models to explain complex experimental results involving the electronic structure of fullerenes, carbon nanotubes and graphite. We will show how experimental data can be accounted by different models with up to thousands of atoms [1-3]. We will also present and discuss cases where accurate dispersion is fundamental, from the, fundamental, intermolecular binding in graphite and fullerene crystals to the curling of graphene in solution [4] and the encapsulation of molecules in nanotubes [5].

References

[1] P. Ruffieux, M. Melle-Franco et al. PRB, 15

(2005) 153403. [2] M. Melle-Franco, M. Marcaccio, D. Paolucci, et

al. JACS, 6, (2004) 1646. [3] D. Paolucci, M. Melle Franco et al. JACS, 23

(2008):739. [4] A. Catheline, L Ortolani, V Morandi, M. Melle-

Franco, C. Drummond, C. Zakri and A. Pénicaud, Soft Matter, 8 (2012) 7882.

[5] TW. Chamberlain , RF. Pfeiffer , J. Howells , H. Peterlik , H. Kuzmany , B. Kräutler , T. Da Ros , M. Melle-Franco , F. Zerbetto , D. Milićand and AN. Khlobystov, Nanoscale, 4 (2012) 7540.

Figures

Figure 1: Frontier orbitals of graphene island with Zig-Zag borders and 9600 carbon atoms calculated with a multiscale tight binding model.


João Nuno Moreira, Lígia Silva and Sérgio Simões CNC - Center for Neuroscience and Cell Biology and FFUC - Faculty of Pharmacy, University of Coimbra, Portugal

[email protected]

T a i l o r i n g N a n o m e d i c i n e s a i m i n g a t a n t i c a n c e r

m o l e c u l a r t h e r a p y

The identification of activated oncogenes, as fundamental genetic differences relative to normal cells, has made possible to consider such genes as targets for antitumor therapy. PLK-1 is a serine/threonine kinase that regulates mitosis entry and progression. It is undetectable in normal tissues but is overexpressed in tumors contributing for the capability of cancer cells to proliferate in an uncontrolled manner. Therefore, effective downregulation of Plk-1 at the tumor level can have a positive impact in the treatment of cancer. Gene downregulation can be efficiently achieved by small-interfering RNAs (siRNAs). However, the clinical use of these molecules has been impaired by their unfavourable pharmacokinetics profile and low intracellular accumulation [1].

A tumor is like an organ encompassing multiple cell types each one contributing to the overall tumor aggressiveness. In this respect, endothelial cells assume a key role in the progression of solid tumors and metastasis formation. Therefore, new therapeutic approaches that preferentially target angiogenesis, in addition to cancer cells, could be tremendously advantageous for the treatment of solid tumors as it compromises the access to oxygen and nutrients impairing tumor survival and proliferation.

The main goal of this work was to design a novel ligand-mediated targeted lipid-based nanocarrier containing an anti-PLK1 siRNA, aiming at targeting, simultaneously, human cancer cells and endothelial cells from angiogenic vessels.

Conclusions

A novel ligand-mediated targeted lipid-based nanocarrier, containing an anti-PLK1 siRNA, aiming at targeting simultaneously, cancer cells and endothelial cells from the angiogenic blood vessels was developed. This novel ligand-targeted sterically

stabilized lipid-based nanoparticle is characterized by high siRNA encapsulation efficiency, efficient protection of siRNA, average size lower than 200 nm, and charge close to neutrality. Overall, these are nanoparticles that present adequate features for systemic administration.

Our results have shown that the covalent attachment of a specific ligand at the extremity of poly(ethylene glycol) chains, brings a major advantage as it significantly improves the internalization of the lipid-based nanoparticle by both human breast cancer cells (MDA-MB-435 and MDA-MB-231), human prostate cancer cells (PC3) and endothelial cells from angiogenic blood vessels (HMEC-1).

Moreover, it was not observed a significant internalization by the non-transformed cell line, BJ fibroblasts, indicating the cellular specificity of the developed targeted nanoparticle.

Treatment of PC3 cells with non-targeted liposomes did not have significant effects on cell viability. In contrast, targeted liposomes encapsulating an anti-PLK1 siRNA resulted in a significant decrease on the cell viability of PC3 indicating that the strategy presented herein may have a truthfully potential in the treatment of solid tumors. Moreover, this decreased on cell viability was a consequence of PLK1 downregulation as it was observed both at the protein and mRNA levels. References

[1] Gomes-da-Silva, L. C., Fonseca, N. A., Moura, V.,

Pedroso de Lima, M. C., Simoes, S., and Moreira, J. N., Acc Chem Res 45 (2012) 1163-1171.


Figures

Figure 1: Impact on the viability of human prostate cancer cells (PC3 cells) after treatment with liposomes containing an anti-PLK1 siRNA. Cell viability was accessed by the Resazurin reduction assay. ***p<0.001 and **p<0.01.

Figure 2: Quantification of PLK1 mRNA on PC3 cells after treatment with liposomes containing an anti-PLK1 siRNA. ***p<0.001 and *p<0.05.


Vera Moura, Sérgio Simões, João Nuno Moreira Treat U, Lda, Rua Alm Gago Coutinho nº17, Coimbra, Portugal

[email protected]

P E G A S E M P – i m p a c t o n t h e t r e a t m e n t o f s o l i d t u m o r s

w i t h a n o v e l m i c r o e n v i r o n m e n t t a r g e t i n g

s t r a t e g y

Cancer is one of the leading causes for mortality in the western civilization of the twenty-first century (WHO, 2009), with more than 1.4 million new cases and more than half a million deaths in 2008, in the United States of America (USA) [1]. In Europe, 2.9 million new cases and 1.7 million deaths were reported in 2004 [2] and, in 2007, the numbers rose to 3.2 million diagnosed cancer cases (excluding non-melanoma skin cancers) and 1.7 million deaths. Unlike hematologic cancers, such as leukemia, accessibility of current treatments to solid cancers is a major obstacle to therapeutic success. Moreover, traditional chemotherapy, upon administration in the blood stream, accumulates extensively in healthy tissues, because it lacks selectivity towards tumor cells. Side effects that occur as a result of the toxic accumulation (hair loss, immune system depression, vomiting and nausea) often lead to administration of anticancer chemotherapeutics at sub-optimal doses, resulting in failure of therapy. This is frequently accompanied by drug resistance and metastatic disease. Targeted therapies to cancer cells, which aim at circumventing these occurrences, can be an appealing alternative, but they have specific disadvantages: (i) patients must be eligible to treatment specificities. This translates into a minor percentage of patients benefiting from therapy; (ii) targeted therapies to cancer cells do not accumulate rapidly and extensively in the tumor mass, for the reason that solid tumors are not readily accessible to therapeutic agents administered in the blood stream, and the increasing pressure gradient towards the inner core of the tumor impairs drug penetration into the compact tumor mass. Cancer is, thus, one disease where there is still an unmet medical need and where more tumor-specific treatments are urgently required.

We have developed a nanotechnology-based platform (PEGASEMP) for the specific (targeted) delivery of a chemotherapeutic drug (doxorubicin) to the tumor microenvironment. Proof of concept was performed in an animal model of breast cancer. PEGASEMP, has proven to accumulate rapid and preferentially in a solid tumor, unlike any other drug delivery nanoparticle. Upon administration in the blood stream, PEGASEMP was able to specifically deliver doxorubicin to the tumor, rapidly (within just 4 h) and efficiently. The reason for this occurrence owes to the dual targeting ability of the platform. Instead of targeting only the cancer cells, PEGASEMP also targets endothelial cells from the tumor blood vessels. PEGASEMP recognizes the one receptor these two cell populations have in common. When reaching the tumor location, PEGASEMP does not depend only on extravasation from the blood stream to accumulate in the target site. The platform recognizes the target cells readily available in the tumor blood vessels and arrests immediately in the tumor site. Hence, we were able to report an accumulation of approximately 50 % the injected dose/g of tissue within only 4 h after administration in the blood stream [3]. This is a major breakthrough if we take into consideration that others have achieved a 5%/g of tissue accumulation over 48 to 72 h when targeting cancer cells within a solid tumor [4]. Nonetheless, increased specificity is not the only advantage PEGASEMP has over other therapeutic options. The platform was engineered to enable a burst release of drug inside the target cells. This triggered release mechanism allows stability in the blood stream (low leakage of the drug from the platform throughout time) and an increased concentration of the drug reaching the tumor site and being effective only where it is necessary.


Moreover, PEGASEMP provides an opportunity for using the same therapeutic agent to treat more than one type of cancer. Given the versatility of the platform, other clinical indications are being investigated for PEGASEMP. If preliminary results prove to be right, the perspective of applying one platform to tumors with diverse histological origins will increase the potential of the technology and give rise to a revolutionary anticancer therapy.

References

[1] Jemal, A., R. Siegel, et al. CA Cancer J Clin 58

(2008). (2): 71-96. [2] Ferlay, J., P. Autier, et al. Ann Oncol 18 (2007)

(3): 581-592. [3] Moura, V., Lacerda, M., et al. Breast Cancer Res

Treat. 133 (2012):61-73 [4] Moreira, J. N., C. B. Hansen, et al. Biochimica et

Biophysica Acta 1515 (2001): 167-176.


M. Conceição Paiva, Rui M. Novais, José A. Covas Instituto de Polímeros e Compósitos/I3N, Universidade do Minho, Campus de Azurém, 4800-058 Guimarães, Portugal

[email protected]

T h e i n f l u e n c e o f c a r b o n n a n o t u b e f u n c t i o n a l i z a t i o n o n

t h e d i s p e r s i o n i n p o l y p r o p y l e n e b y m e l t

b l e n d i n g

Polymer composites containing carbon nanotubes (CNT) are expected to present exceptional electrical, mechanical and thermal properties, even at low incorporation content. Polypropylene (PP) has a wide spectrum of applications due to its processability, good balance of physical properties and price, thus PP/CNT composites have a high potential for applications requiring electrical conductivity and/or high mechanical strength. The practical application of PP composites is hindered by the ability to achieve good CNT dispersion using industrial-scale melt mixing processes. This problem is inherent to all CNT/polymer mixtures due to the physical form of the CNT, that grow in the form of highly entangled agglomerates of several microns or even millimeters. Also, the chemical inertia of the CNT surface leads to a poor polymer/CNT interface.

The present works focuses on the study of the joint effects of chemical functionalization and melt blending on CNT dispersion in PP, and on the electrical and tensile properties of the resulting composites. The CNT modification was performed using a non-aggressive method that preserves the aspect ratio of the tubes [1] and the functionalization reaction was tailored considering compatibility with the PP matrix. The as-received and functionalized CNTs were melt blended with PP by twin-screw extrusion and the processing conditions were varied. The dispersion was assessed by optical and scanning electron microscopy, showing a large dependence on the processing conditions, and also on the functionalization route.

The functionalization products were studied by XPS and TGA that confirmed the formation of cyclic amine groups bonded to the CNT surface (CNT250). The CNT thus functionalized were further reacted with maleic anhydride grafted PP, forming PP-functionalized CNT (CNT250/PP-g-MA). XPS spectra showed the extensive coverage of the CNT surface

with PP and the formation of amide bonds between CNTs and grafted PP, as illustrated in Figure 1.

The melt mixing studies focused the analysis of the dispersion of large CNT loading of 4 wt. % [2]. It was observed that the CNT dispersion was generally improved for composites processed at higher screw speed and lower throughput. The composites formed with polymer modified CNT showed distinctive nanotube dispersion, presenting a large number of small CNT agglomerates, as opposed to a smaller number of large CNT agglomerates observed for the composites with non-functionalized, as depicted in Figure 2. The electrical properties of the composites correlated with dispersion level attained, as shown in Figure 3. The incorporation of polymer-functionalized CNT in PP led to an improvement in tensile modulus greater than 30% relative to the composites with similar composition of non-functionalized CNT. However, the electrical resistivity was higher for the CNT250/PP-g-MA composites.

Acknowledgements The authors acknowledge the financial support from the Portuguese FCT through project PEst-C/CTM/LA0025/2011 and PhD grant SFRH/BD/32189/2006. References

[1] M. C. Paiva, F. Simon, R. M. Novais, T.

Ferreira, M. F. Proença, W. Xu, F. Besenbacher. ASC Nano, 4, 12 (2010) 7379.

[2] R. M. Novais, F. Simon, M. C. Paiva, J. A. Covas, Composites: Part A, 43 (2012) 2189.


Figures

Figure 1: CNT functionalization products: a) reaction of the pyrrolidine groups with the maleic anhydride grafted on PP-g-MA; XPS high-resolution C 1s spectra acquired from: b) unmodified CNTs, and c) CNT250/PP-g-MA. The intensity of the spectrum presented for c) is fivefold that of spectrum b).

Figure 2: Comparison of the cumulative agglomerate area ratios measured for composites processed at 80 rpm and 40 g/h. The insert optical micrographs illustrate the agglomerate dispersion attained.

Figure 3: Correlation between agglomerate area ratio (ratio between the composite area covered by CNT agglomerates and the total composite area analyzed) and electrical resistivity for composites with 4 wt% of as-received and functionalized CNTs produced under various processing conditions.

1.E-01

1.E+01

1.E+03

1.E+05

1.E+07

1.E+09

0 2 4 6 8 10 12 14

Ele

ctri

cal r

esi

stiv

ity

(O

hm

.m)

Area ratio (%)

PP/CNT PP/CNT210 PP/CNT250 PP/CNT250/PP-g-MA


Clara Pereira1, Tânia Pinto1,2,

Andreia Monteiro1,2, Bruno Jarrais2, Carla Silva2, José Morgado3, Manuel F. R. Pereira4 and Cristina Freire1 1REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Portugal 2Centro de Nanotecnologia e Materiais Técnicos, Funcionais e Inteligentes (CeNTI), Portugal 3Centro Tecnológico das Indústrias Têxtil e do Vestuário de Portugal (CITEVE), Portugal 4Laboratório de Catálise e Materiais (LCM), Laboratório Associado LSRE/LCM, Departamento de Engenharia Química, Universidade do Porto, Portugal

[email protected]

E n g i n e e r e d N a n o m a t e r i a l s f o r t h e D e v e l o p m e n t o f F u n c t i o n a l T e x t i l e s :

F r o m C o n c e p t t o T e c h n o l o g i c a l A p p l i c a t i o n s

Over the years, engineered nanomaterials, such as hybrid silica nanoparticles, magnetic nanomaterials and nanoclays have been at the leading edge of Nanotechnology innovation. Their remarkable and tunable properties boosted the development of a new generation of high-tech functional textiles with novel functionalities ((super)hydro/oleophobicity, radiation protection, photochromism, fire retardancy, etc.) [1].

REQUIMTE and LSRE/LCM research groups have been engaged on the design and functionalization of novel hybrid silica nanoparticles, superparamagnetic nanomaterials and nanoclays with engineered properties for the fabrication of functional textiles with improved performance. The nanomaterials incorporation onto textiles at a semi-industrial pilot scale and the assessment of their properties have been accomplished through the collaboration with the Centre for Nanotechnology and Smart Materials (CeNTI) and the Portuguese Technological Centre for the Textile and Clothing Industry (CITEVE).

In this work we will provide an overview of our recent breakthroughs achieved in the last few years for the development of high-tech textiles with water/oil repellence, flame retardancy, radiation protection, photochromism/thermochromism.

Superamphiphobic cotton fabrics were produced through a novel one-pot process consisting on their in situ coating with ~45 nm mesoporous silica nanoparticles (MSNs) functionalized with fluorocarbon groups (Figure 1) [2]. To achieve this

goal, the MSNs were prepared and simultaneously functionalized with a fluoroalkoxysilane (F13), under alkaline conditions in the presence of the fabric (co-condensation process). The influence of the F13 loading on the topology, degree of functionalization and hydro/oleophobicity of the fabrics was evaluated. All the functional textiles presented superhydrophobic properties (water contact angle > 150°) due to the combination between the surface roughness imparted by the MSNs and the low surface energy provided by the organosilane. Additionally, the textile with the highest loading of fluorocarbon groups was superamphiphobic.

The methodology developed in this work presented several advantages over other processes reported in literature since it was more efficient, less time-consuming and allowed the functionalization of the textile with MSNs and fluorine-based groups in a single step.

Novel cotton textiles with flame retardancy properties were also designed through their derivatization with nanoclays (Figure 2) [3]. The K10-montmorillonite nanoclay was functionalized with suitable organic groups and then incorporated onto cotton through a dyeing-like route which mimics the traditional dyeing processes used in Textile Industry. The characterization techniques confirmed the successful incorporation of the nanoclays into the fabrics. Furthermore, upon ten washing cycles, only a small clay leaching was detected by scanning electron microscopy, X-ray photoelectron spectroscopy and thermogravimetry, suggesting a


high stability of the coating to washing. The flame retardancy properties of the novel fabrics were examined using the Portuguese standard NP EN 6941 (2005). Upon the functionalization of the fabric with the nanoclays, there was only a small increase of the burning time probably due to the low loading of clay per mass of substrate. On-going work is currently in progress to incorporate higher loadings of nanoclay while maintaining identical immobilization efficiency upon washing.

More recently, a novel generation of magnetic cotton and polyester textiles has been developed at a semi-industrial scale through their coating with superparamagnetic iron oxides and nanoferrites by wet exhaustion and impregnation processes used in Textile Industry (Figure 3). The magnetic nanoparticles incorporated onto the fabrics were prepared by a novel one-step methodology which allowed the reduction of the particle size and simultaneously the enhancement of the magnetic properties [4]. Furthermore, the new aqueous route was cost effective, eco-friendly and led to the production of the tailored magnetic nanomaterials in high yields.

In the field of photochromism, we have recently produced UV-light responsive textiles using two distinct industrial scale advanced methods: (i) textile printing and (ii) production of sheath-core fibers through the extrusion process with subsequent knitting. To achieve this goal novel photochromic silica nanoparticles were firstly prepared by co-condensation between the silica precursor tetraethoxysilane and a quaternary alkylammonium organosilane and subsequent functionalization with a polyoxometalate. The resulting hybrid nanoparticles exhibited efficient photochromic properties with a color change from green to blue upon UV irradiation (λ=254 nm), which were preserved upon their incorporation onto textiles.

Acknowledgements

This work was funded by Fundação para a Ciência e a Tecnologia (FCT) and FEDER through grant no. PEst-C/EQB/LA0006/2011 and through project ref. PTDC/CTM/108820/2008 in the framework of Program COMPETE. C.P. thanks FCT for the postdoctoral grant SFRH/BPD/79606/2011.

References

[1] B. Mahltig, H. Haufe, H. Böttcher, J. Mater.

Chem. 15 (2005) 4385. [2] C. Pereira, C. Alves, A. Monteiro, C. Magén, A.

M. Pereira, A. Ibarra, M.R. Ibarra, P.B. Tavares, J.P. Araújo, G. Blanco, J.M. Pintado, A.P. Carvalho, J. Pires, M.F.R. Pereira, C. Freire, ACS Appl. Mater. Interfaces 3 (2011) 2289.

[3] A. Monteiro, C. Pereira, B. Jarrais, M.F.R. Pereira, C. Freire, AUTEX2012, Book of Proceedings, Volume I, Faculty of Textile Technology, University of Zagreb, Croatia, 2012, pages 719–724.

[4] C. Pereira, A.M. Pereira, C. Fernandes, M. Rocha, R. Mendes, M.P. Fernández-García, A. Guedes, P.B. Tavares, J.-M. Grenèche, J.P. Araújo, C. Freire, Chem. Mater. 24 (2012) 1496.

Figures

Figure 1: Left: Scheme of the functionalization of cotton with F13-derivatized MSNs (not drawn to scale). Right: SEM micrograph of the functional textile prepared with TEOS:F13 = 5:1, water and oil droplets on the fabric surface and contact angle values (* not possible to determine).

Figure 2: Schematic representation of functionalization of cotton textile with K10 nanoclay modified with organosilane and flame retardancy evaluation of the resulting fabric.

Figure 3: Magnetic textiles functionalized with superparamagnetic nanoparticles.

+


Eulália Pereira1, João Luz2, Leonor

Soares1,2, Cláudia Couto2, Ricardo Franco2 1REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, Portugal 2REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal

[email protected]

N a n o b i o c o n j u g a t e s o f t y r o s i n a s e a n d l a c c a s e w i t h

g o l d n a n o p a r t i c l e s : e f f e c t o f c o u p l i n g m e t h o d a n d c a p p i n g

a g e n t o n e n z y m a t i c a c t i v i t y

Bionanoconjugates of enzymes and metal nanoparticles are increasingly used in a wide range of applications, namely development/optimization of sensors and biosensors, development of new carriers for intelligent drug delivery and diagnostic, probes for biological processes, etc [1]. Several methodologies for the preparation of bionanoconjugates are currently known, either based on adsorption or on covalent coupling. The adsorption of protein molecules at AuNPs is a complex process that, depending on the conformational stability of the protein and the surface properties and morphology of the AuNPs, can lead to significant changes in the protein structure. The adsorption is usually a two-step process: a fast adsorption step due mainly to electrostatic attraction, followed by a slower rearrangement step where other Van der Waals forces (e.g. hydrophobic interactions, acid-base adduct formation, dipole-dipole interactions, hydrogen bonding) combine to optimize the orientation and structure of the protein at the AuNP surface. In this second step, replacement of water molecules, ions, and capping agent may occur. This rearrangement step may induce severe distortions, e.g. by exposing internal hydrophobic residues of the protein to the Au surface, which may be detrimental or advantageous to the biological function of the protein. In addition, curvature effects and lateral protein-protein interactions (crowding effect) may lead to cooperativity or anti-cooperativity in the biological function of the protein. The surface properties of AuNPs (imparted by the capping agent) and proteins is the key factor in the adsorption process, hence an easy way to improve the properties of protein-AuNP conjugates is to alter the surface chemistry of the AuNP, by

changing the capping agent, thus modulating the affinity and denaturing properties of the AuNPs. On the other hand, chemical coupling of proteins with AuNPs may be detrimental to the biological function. In this case, the main factors are the low selectivity of the coupling methods to the surface of the AuNPs (leading to cross-linking of proteins) and random orientation of the protein in the AuNPs (possible hindering key sites in the protein, e.g. substrate binding sites). The choice of the appropriate method for the preparation of bionanoconjugates is currently made on a caseby-case basis, since phenomena that rule the interactions between nanoparticles and proteins are still poorly understood [2]. In order to better understand bionanoconjugate formation and properties, we have focused on the study of bionanoconjugates of two oxidases, tyrosinase from mushroom and laccase from lacquer tree, with 15 nm gold nanoparticles (AuNPs). Both enzymes are copper containing oxidases that have numerous applications on biosensing, bioremediation and other biotechnological industrial processes [3]. Two different approaches for the formation of bionanoconjugates were compared, namely electrostatic adsorption and covalent coupling using chemical cross-linking agents (EDC/NHS). In addition, AuNPs with different capping agents (citrate, MUA and the pentapeptides CALNN and CALKK) and different morphologies (spheres and triangular plates) were used to evaluate the influence of the capping agent/curvature. The saturation ratio [enzyme]/[AuNP] was determined by zeta-potential measurement and by agarose gel electrophoresis of the electrostatic bionanoconjugates. The saturation


ratio of adsorbed [enzyme]/[AuNP] changes only slightly with the capping agent and the enzyme and it is reached with a 70-90 molar excess of protein (Fig. 1). This excess molar ratio was then used in the preparation of the bionanoconjugates. The enzymatic activity of the bionanoconjugates was determined and compared with the free enzyme. The bionanoconjugates were centrifuged, and the enzymatic activity of the pellet and supernatant were compared, to ascertain the quantity of adsorbed protein. For electrostatic coupling a small but reproducible increase of enzyme activity was observed for both enzymes, in all the bionanoconjugates. Further analysis of the enzymatic activity for laccase-AuNPs and tyrosinase-AuNPs shows that the increased activity is due to an increase in the catalytic turnover and an increase in the affinity of the adsorbed laccase for the substrate. For laccase bionanoconjugates, the pH profile of enzymatic activity also changes, with a deviation of the optimal pH from 7.5 to 6.5 in the bionanoconjugates (Fig. 2). On the other hand, for EDC/NHS coupling, a small decrease in enzymatic activity was always observed. In addition, this method seems to be very sensitive to small changes in the experimental conditions used for the preparation of the nanobioconjugates. The results will be discussed in terms of the advantages and disadvantages of both methodologies of preparation of bionanoconjugates and the relevance of the various characterization methods used. References

[1] P. V. Baptista, G. Dória, P. Quaresma, M.

Cavadas, C. S. Neves, I. Gomes, P. Eaton, E. Pereira, R. Franco, "Nanoparticles in Molecular Diagnostics" in Progress in Molecular Biology and Translational Science, A. Villaverde (Ed.), Burlington: Academic Press, 104 (2011), p. 427-488.

[2] J. Cortez, E. Vorobieva, D. Gralheira, I. Osório, L. Soares, N. Vale, E. Pereira, P. Gomes, R. Franco, J. Nanopart. Res., 13 (2011) 1101–1113

[3] R. Franco, E. Pereira, "Interactions of Gold Nanoparticles with Proteins" in Encyclopedia of Metalloproteins, V.N. Uversky, R.H. Kretsinger, E.A. Permyakov (eds.), Springer-Verlag: 2012

Figures

Figure 1: Variation of zeta-potencial with the ratio [Tyrosinase]/[AuNP] for different capping agents. (Tyr-AuNP@cit: citrate capped AuNPs; Tyr-AuNP@MUA: MUA capped AuNPs; Tyr-AuNP@CALNN:CALNN capped AuNPs).

Figure 2: Comparison between the catalytic efficiency (kcat/KM) values for free Laccase (blue) and bionanoconjugates (red) at pH 6.0-8.5.


Juan N. M. R. Peres1, Yu. V. Bludov1,

Aires Ferreira2 and M. I. Vasilevskiy1 1Department of Physics and Center of Physics, University of Minho, Campus de Gualtar, P-4710-057, Braga, Portugal 2Graphene Research Centre and Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542

[email protected]

E x a c t s o l u t i o n f o r s q u a r e -w a v e g r a t i n g c o v e r e d w i t h

g r a p h e n e : S u r f a c e p l a s m o n s -p o l a r i t o n s i n t h e T H z r a n g e

We provide an analytical solution to the problem of scattering of electromagnetic radiation by a square-wave grating with a flat graphene sheet on top (see figure). We show that for deep groves there is a strong plasmonic response with light absorption in the graphene sheet reaching more than 45%, due to the excitation of surface plasmon-polaritons. The case of grating with a graphene sheet presenting an induced periodic modulation of the conductivity is also discussed.

Figure 1: Geometry of the problem. The incident angle and the incoming wave number are depicted. The radiation is p-polarized. A top gate for the electrostatic doping of graphene can be arranged as a transparent electrode placed at some distance above the graphene sheet. Alternatively, a bottom gate can be placed below the dielectric substrate.

References

[1] N. M. R. Peres, Yuliy V. Bludov, A. Ferreira,

Mikhail I. Vasilevskiy, Exact solution for square-wave grating covered with graphene: Surface plasmon-polaritons in the THz range, arXiv:1211.6358.

[2] Yuliy V. Bludov, Mikhail I. Vasilevskiy, Nuno M. R. Peres, Tunable graphene-based polarizer, J. Appl. Phys. 112, 084320 (2012).

[3] N. M. R. Peres, A. Ferreira, Yu. V. Bludov, M. I. Vasilevskiy, Light scattering by a medium with a spatially modulated optical conductivity: the case of graphene, J. Phys.: Condens. Matter 24, 245303 (2012).

[4] Yuliy V. Bludov, Nuno M. R. Peres, Mikhail I. Vasilevskiy, Graphene-based polaritonic crystal, Phys. Rev. B 85, 245409 (2012).

[5] A. Yu. Nikitin, F. Guinea, F. J. Garcia-Vidal, L. Martin-Moreno, Surface plasmon enhanced absorption and suppressed transmission in periodic arrays of graphene ribbons, Phys. Rev. B 85, 081405(R) (2012).


Julia Pérez-Prieto Instituto Ciencia Molecular (ICMol), Universitat de Valencia, C/ Catedrático José Beltrán, 2, 46980 Paterna, Valencia, Spain

S y m b i o s i s b e t w e e n n a n o p a r t i c l e s a n d t h e i r

o r g a n i c l i g a n d s

Optically active, spherical, metal- and semiconductor-nanoparticles (NPs) are smart systems that exhibit unique properties, such as a high surface-to-volume ratio and size-dependent properties [1]. They can be capped with a considerable number of organic ligands, which not only provide the NP periphery with the hydrophobicity or hydrophilicity needed to give rise to stable organic or aqueous NP colloidal solutions, respectively, but may introduce functionality at the NP periphery. In this case, the NP would act as a 3D-scaffold which makes it possible to provide a high local concentration of a functional moiety, such as fluorophores, photosensitisers, antioxidants, etc. It should also be taken into account that the organic capping can establish specific interactions, either at the NP periphery or within the organic shell, with nearby compounds. This can result in a change of the nanoparticle optical properties and/or the (photo)physical properties of the ligand functional group [2,3].

In this presentation I will comment on systems recently developed by our research group showing how the symbiosis between the nanoparticle and their ligands can be beneficial for the nanohybrid application.

Acknowledgements: Financial support from the Spanish MICINN (CTQ2011-27758) is acknowledged. References

[1] A. P. Alivisatos, J. Phys. Chem. 1996, 100, 13226;

R. Sardar, A. M. Funston, P. Mulvaney, R. W. Murray, Langmuir, 2009, 25, 13840 ; T. K. Sau, A. Pal, M.C. Daniel, D. Astruc, Chem. Rev. 2004, 104, 293.

[2] C. E. Agudelo-Morales, R. E. Galian, J. Pérez-Prieto, Anal. Chem. 2012, 84, 8083.

[3] J. Aguilera-Sigalat, J. M. Casas-Solvas, M. C. Morant-Miñana, A. Vargas-Berenguel, R. E. Galian, J. Pérez-Prieto, Chem.Comun., 2012, 573.


Ana Paula Piedade CEMUC-GNM*-Departamento de Engenharia Mecânica da Faculdade de Ciências e Tecnologia da Universidade de Coimbra, Rua Luís Reis Santos, 3030-788 Coimbra, Portugal

[email protected]

S p u t t e r i n g a n d n a n o s u r f a c e m o d i f i c a t i o n o f b i o m e d i c a l

d e v i c e s

The conjugation between optimal bulk performances with appropriate surface properties/characteristics in biomedical implantable devices is rarely achieved within the same material. The need occurs to modify the surface of such devices in order to obtain the suitable response from the biological environment.

One of the major concerns related with this type of approach is the stress developed in the interface bulk/coating due to the discrepancy of mechanical and chemical properties. In nature, these problems are controlled by gradually varying the material behavior through a structure, i.e, by bio-functional graded materials. Another biological approach also includes the development of hybrid organic/inorganic materials. The same strategies in tailoring biomaterials can be used.

In the last years the GNM has exploited different approaches for the modification, by r.f. magnetron sputtering, of biomedical materials just to name a few - vascular stents[1,2] and neural implants[3], By optimizing the deposition parameters allows to modify the surface topography, morphology and chemical functionality in order to achieve the desired performance. In this work it is briefly reported some of the developed research in the nanomedicine area.

In the modification of 316L stainless steel vascular stents the strategy was to chemically match the bulk and the coating material by a chemical graded thin film with a sub-micrometric thickness. The thin films were co-deposited from 316L stainless steel and poly(tetrafloroethylene) (PTFE) targets. The optimized procedure allowed to achieve a functionally graded thin film (2D-FGM) consisting of a metallic composition near the vascular stent and a polymeric material in the outmost surface. Conjugated with the gradual transition in chemical composition the thin films presented a

nanocomposite structure (Figure 1). This solution allowed a very fast re endothelisation of the coated stent when compared to the uncoated one, suggesting that the problems of reestenose associated with implanted stents are reduced.

The study on the modification of surfaces with hybrid PTFE/Au thin films intended to address two distinctive but important problems. The first one related to ensuring the correct positioning of some implantable devices into the human body. The solution is to introduce in the coating, (nano)materials with high electronic density such as gold. The other problem is generic and related with all implantable devices: the rejection of the “foreign” materials by the human body. Although very complex and not fully understood this process begins with the adsorption of biological proteins that, due to the subsequent denaturation, trigger the rejection biological pathways. The use of a polymeric material is usually more favorable in preventing the loss of protein 3D conformation. The co-deposition of the two materials induced a hybrid nanocomposite structure. The developed surfaces permitted the adsorption of bovine serum albumin without protein denaturation (Figure 2).

Another line of research aims at the development of antimicrobial coatings for biomedical devices. In this area the development of thin films with hybrid organic/inorganic matrix doped with antimicrobial metals is being studied. The co-deposition of hydroxyapatite (HA) and PTFE doped with silver which, for selected deposition parameters, creating surfaces with an inhomogeneous phase distribution could be cited as an example. This feature appears to induce on the same surface the ability to, simultaneously, promote and inhibit the growth of selected bacterial strains (Figure 3).

*CEMUC-GNM – Center of Mechanical Engineering of the University of Coimbra- Group of Nanomaterials and Micromanufacturing


References

[1] A.P. Piedade, J. Nunes, M.T. Vieira, Acta Biomater., 4 (2008) 1073. [2] A.P. Piedade, J. Nunes, M.T. Vieira, J. Nanosci. Nanotechno., 8 (2008) 1. [3] J. Nunes, R.J. Santos Santos, V. Loureiro, A.P. Piedade, Plasma Process. Polym. 9 (2012) 709.

Figures

Figure 1: Stainless steel vascular stent coated with a hybrid nanocomposite thin film of stainless steel PTFE. a) HR-TEM of a film with 11at.% of fluorine; b) HR-TEM of the selected area; c) Inverse discrete Fourier transform of (b) identifying iron fluoride nanocristallites within the amorphous matrix.

Figure 2: AFM characterization of a PTFE/Au nanocomposite thin film. As deposited topographic (a) and phase images (b) and after BSA immobilization c) topographic image. (bar = 400nm).

Figure 3: a) TEM bright field image of an inhomogeneous phase distribution of a PTFE/HA/Ag hybrid thin film; b) SEM image of Bacillus cereus after 24h incubation on the same surface.


Akhilesh Rai1,2, Marta B. Evangelista1,2,

Sandra Pinto2 and Lino S. Ferreira1,2 1BIOCANT, Parque Tecnológico de Cantanhede, Cantanhede, Portugal 2CNC, Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Coimbra, Portugal

[email protected]

D e s i g n o f p o t e n t a n t i m i c r o b i a l a n d

b i o c o m p a t i b l e g o l d n a n o p a r t i c l e s

With significant advances in nanotechnology over recent years, nanomaterials with unique chemical and physical properties have gained increasing interests in biotechnological, biomedical and pharmaceutical fields [1]. Gold nanoparticles are prime candidates as novel carriers to deliver drug, DNA and enzymes owing to their larger surface area to volume ratio and no toxicity to human cells [2]. Among potential drug molecules, the conjugation of antimicrobial peptides with metal nanoparticles has several advantages such as increasing the half-life of the antimicrobial peptides, enhancing the activity against microorganisms as well as improving the chemical stability under a wide range of storage conditions. The process of conjugating antimicrobial peptides with metal nanoparticles is a complex chemical process and requires multiple steps involving the synthesis of metal nanoparticles, surface functionalization and finally coating of the peptides.

In this work, we have shown one pot synthesis of gold nanoparticles and their capping with antimicrobial peptide (name not disclosed due to confidentiality) in the presence of HEPES buffer. Different sizes of spherical gold nanoparticles are synthesized using antimicrobial peptide at buffer pH ranging from 5 to 7.5. The rate of reduction of gold ions in aqueous solution is controlled by cysteine residue of peptide, which plays an important role in controlling the size of the gold nanoparticles. Fourier transform infrared spectroscopy (FTIR) revealed that the capped antimicrobial peptides on the gold nanoparticle surface have random coiled secondary structures while the native peptides contain α-helix and β-sheet structures [3]. Antimicrobial peptides adopt α-helical structures in the presence of membrane, which trigger them to act as potent antimicrobial agents [3]. Antimicrobial peptide capped gold nanoparticles exhibit potent

antimicrobial activity against Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) bacteria as compared to peptide alone in the presence of human serum. The enhanced antimicrobial activity is due to the combined action of antimicrobial peptide and gold nanoparticles, which increases the permeability of bacterial cell membranes, resulting in the leakage of cell contents and eventually cell death. We further showed that the synthesized gold nanoparticles are biocompatible to Human Umbilical Vein Endothelial Cells (HUVECs) and Normal Human Dermal Fibroblast cells (NHDF) up to 100 μg/mL while 20 μg/mL antimicrobial peptide alone is cytotoxic to these cells, indicating that the peptide coated gold nanoparticles can be used as potent antimicrobial materials to treat infectious diseases. References

[1] Rai A. Prabhune A. Perry C. C. J. Material

Chemistry, 20 (2010), 6789. [2] Zhang R, Servos MR, Liu, J. Langmuir 28 (2012),

3896. [3] Sato H, Feix JB, Biochim Biophys Acta, 1758

(2006), 1245.


Sohel Rana1, Amitava Bhattacharyya2,

Shama Parveen1, Raul Fangueiro1, Ramasamy Alagirusamy3, Mangala Joshi3 1School of Engineering, University of Minho, Campus de Azurem, Guimarães 4800-058, Portugal 2Nanotech Research Facility, PSG Institute of Advanced Studies, Coimbatore - 641004, India 3Department of Textile Technology, Indian Institute of Technology, Hauz Khas, New Delhi 110016, India

[email protected]

D e v e l o p m e n t a n d c h a r a c t e r i z a t i o n o f c a r b o n

n a n o t u b e d i s p e r s e d c a r b o n / p h e n o l i c m u l t i - s c a l e

c o m p o s i t e s

Multi-scale composite materials are the latest generation fibre reinforced composites (FRCs), in which nano-scale reinforcements are used in conventional FRCs to introduce multi-functional properties [1]. Epoxy resin based multi-scale composites have been researched and reported extensively [2-4] in recent times. However, phenolic resins are also widely used for various applications including development of carbon-carbon composites, which find uses in many high end sectors such as spacecraft re-entry frames, aircraft brakes, etc [5]. Nevertheless, studies on the carbon/phenolic multi-scale composites can be rarely found in the literature. Therefore, the present study aims at the development of high performance carbon/phenolic multi-scale composites with improved mechanical, thermal and tribological properties. Multi-walled CNTs were dispersed in to phenolic resin using an optimized dispersion route and, carbon fabrics were subsequently impregnated with the CNT dispersed resin to develop carbon fibre/phenolic resin/CNT multi-scale composites. Mechanical, dynamic-mechanical, thermal and tribological properties of multi-scale composites were characterized. It was observed from the dispersion studies that an optimized dispersion route that uses a combination of ultrasonication (6 hours) with mechanical stirring (7 hours) and 0.2% nonionic surfactant can homogeneously disperse CNTs within phenolic resin. According to the results of mechanical tests, incorporation of only 1.5 wt.% CNT resulted in 46% improvement in Young´s modulus, 9% increase in tensile strength and 150% improvement in breaking strain of neat carbon/phenolic composites (Figure 1). As a result, a strong improvement was observed in the toughness of carbon phenolic composites through dispersion of CNTs. In addition to that, thermal conductivity improved by 167%. Incorporation of CNT also

increased the storage modulus of carbon/phenolic composites as observed in the dynamic mechanical analysis. Weight loss of composites, when subjected to friction and wear tests, also decreased considerably through dispersion of CNTs. Therefore, these newly developed carbon/phenolic multi-scale composites can replace the conventional ones in many high performance applications due to their improved performance. References

[1] S. Rana, R. Alagirusamy, M. Joshi, Carbon

Nanomaterial Based Three Phase Multi-functional Composites, LAP LAMBERT Academic Publishing, Germany (2012).

[2] S. Rana, R. Alagirusamy, M. Joshi. Compos Part A, 42(2011) 439-445.

[3] E. Bekyarova, E. T. Thostenson, A. Yu, H. Kim, J. Gao, J. Tang, H. T. Hahn, T. W. Chou, M. E. Itkis, R. C. Haddon, Langmuir, 23(2007) 3970–3974.

[4] E. T. Thostenson, J Appl Phys, 91(2002) 6034-6037.

[5] L. M. Manocha, Sadhana, 28(2003) 349–358.


Figures

Figure 1: Improvement of elastic modulus (a), tensile strength (b) and strain at break (c) of carbon/phenolic composites through incorporation of only 1.5 wt.% multi-walled CNTs


Eva Rauls and Wolf Gero Schmidt University of Paderborn, Theoretical Physics, Warburger Str. 100, 33100 Paderborn, Germany

[email protected]

F o r m a t i o n o f t h i n o r g a n i c l a y e r s a t t h e e x a m p l e o f C o -

a n d C u - P h t h a l o c y a n i n e s o n A u - s u b s t r a t e s – a t h e o r e t i c a l

i n v e s t i g a t i o n

Phthalocyanines (Pc) with or without a metal center are currently under intense investigation in surface physics. The biocompatibility of these molecules together with their chemically tunable electronic structure makes them for instant highly interesting for energy transfer processes in medical applications. Furthermore, in nanotechnology, they are especially useful due to their flexibility, since the basis of these molecules, i.e. the porphyrin core, can easily be varied with different functional groups substituting parts of the molecule or simply attached to the core of the molecule. Upon exchanging the center atom, the binding energy to a substrate, the molecular deformation or the spin state can be tailored.

In this work, we present our first principles investigations of Co-Pc and Cu-Pc on Au(100)-surfaces.

In contrast to our previous studies on tetraphenyl porphyrins on Au(111) [1,2] or metal-free phtalocyanines on Au(110) [3], the flat surface geometry of Au(100) does not induce the strong deformations we observed for these cases. A comparatively strong interaction of the complete molecule with the substrate is observed. In our work, we investigated high coverage structures as a first step towards the organic/inorganic interface as is useful for organic electronic devices.

Taking the next steps, we moved on towards the formation of multiple molecular layers.

In experiment, a structural transformation is observed, with the molecules lying flat in the beginning and moving to a standing arrangement for higher Pc film thicknesses. Experiments give a hint that a buried interface structure is formed, the structure of which we address by our calculations. A variety of two-, and three-layer thick molecular adsorbates have been investigated.

While simulated STM-images do not uniquely revolve the number of layers below, the density of states shows some characteristic shifts, especially of the d-orbitals at the Co-center. References

[1] S. Muellegger, E. Rauls, et al. ACS Nano 5, 6480

(2011). [2] S. Müllegger, M. Rashidi, T. Lengauer, E. Rauls,

W. G. Schmidt, G. Knor, W. Schöfberger, and R. Koch, Phys. Rev. B 83 , 165416, (2011).

[3] E. Rauls, W.G. Schmidt, T. Pertram, K. Wandelt, Surf. Sci. 606, 1120, (2012).


Figures

Figure 1: Schematic representation of the formation of multiple molecular layers.

Figure 2: State-decomposed density of states at the Co-center of Co-Pc-molecules in a single layer (left) or a double layer (right) of molecules.

Figure 3: Calculated charge density differences upon adsorption of 1, 2, or 3 Co-Pc molecules on a Au(100) surface.

Co

Au

Co, bottom

Au, surface

EFermi

Co, top


Nuno Rocha, Arménio Serra and C. Jorge Coelho Department of Chemical Engineering, University of Coimbra, Pólo II, Pinhal de Marrocos, 3030-790 Coimbra, Portugal

[email protected]

D e v e l o p m e n t o f p o l y m e r -b a s e d s e l f - a s s e m b l y s y s t e m s

f o r a d v a n c e d a p p l i c a t i o n s

In recent years, the application of living polymerization concept to radical polymerization has allowed developing the so-called controlled/”living” radical polymerization methods [1]. The high chemical tolerance of radical polymerization allowed, for the first time, to prepare polymeric materials of pre-determined narrow molecular weight distributions and telechelic structure from a broad range of monomers. Additionally, the living nature of the prepared polymers by CLRP made possible the design and preparation of block copolymers of well defined composition, molecular weight and architecture, which were not possible to be afforded using the available polymerization technology.

In block copolymers, the thermodynamic incompatibility of their polymeric segments, while bonded covalently, leads to phase separation at a nanometer size range that is crucial for the preparation of well defined nanostructured materials [2]. For this reason, block copolymers have been for long known as a solution to tailor property profiles of synthetic materials and as effective compatibilizers or dispersion promoters, for a wide variety of applications based in polymeric formulations, such as in plastics, coatings, micro-optoelectronics or even in biomedicine.

For the last few years, our research group has been involved in the development of CLRP methods to prepare block copolymers for advanced applications. Development of this methodology using methods applicable to a semi-industrial scale allowed obtaining poly(vinyl chloride) (PVC) block copolymers including flexible poly(n-butyl acrylate) (PnBA)[3] and hydrophilic poly(hydroxypropyl acrylate) (PHPA) segments with reasonable control over their molecular weight distribution and composition[4]. These materials were shown to be able to provide PVC-based materials with, respectively, enhanced flexibility, without the need of using external plasticizers [5], and improved

thermal stability and interaction properties to other hydrophilic materials, such as to wood flour [6]. PVC and PHPA were further shown to be effective coupling agents in PVC and wood flour composites, providing composites with superior mechanical performance [7].

Additionally, the self-assembly of block copolymers in solution media has been explored to afford complex and well defined structures as nature has always done in biological systems [8]. Depending on the nature of the polymeric segments used, these systems may even respond to environmental stimuli and by this way, change their self-assembly structure, providing a change in their performance properties or providing a triggerable release of specific components. This methodology has received significant interest for the development of new polymer-inorganic hybrid nanoparticles or for advanced drug delivery applications [9].

On the hybrid nanoparticles development, recently, we have developed superparamagnetic iron oxide nanoparticles based on aqueous self-assembly of Fe3O4 nanoparticles in the presence of an amphiphilic block copolymer that contained a good steric stabilizer and polymeric segment that can coordinate metallic species. The effect of changing the block copolymers composition and molecular weight on the hybrid nanoparticle formation was studied. Additionally, the introduction of other polymeric segments, such as a responsive and a mechanical stability enhancer, to afford responsive magnetic nanoparticles was evaluated [10, 11].

Furthermore, some of our recent research work has been involved in the development of polymeric structures via CLRP methodologies for biomedical applications, including the development of advanced polymer-liposomes systems, highly branched stimuli-responsive polymeric-structures or controlled drug delivery. An overview of the synthesis strategies that are accessible from CLRP


methodologies to afford these advanced self-assembly structures will be provided and their potentialities for advanced biomedical applications will be discussed. References

[1] W. A. Braunecker, K. Matyjaszewski, Prog.

Polym. Sci. 2007, 32, 93. [2] M. R. Bockstaller, R. A. Mickiewicz, E. L. Thomas,

Advanced Materials 2005, 17, 1331. [3] J. F. J. Coelho, M. Carreira, A. V. Popov, P. M. O.

F. Goncalves, M. H. Gil, European Polymer Journal 2006, 42, 2313.

[4] N. Rocha, Coelho, J. F. J., Barros, B., Cardoso, P. M. L., Gonçalves, P. M., Gil, M. H. and Guthrie, J. T., Journal of Applied Polymer Science 2012, early view.

[5] J. F. J. Coelho, M. Carreira, P. M. O. F. Goncalves, A. V. Popov, M. H. Gil, Journal of Vinyl & Additive Technology 2006, 12, 156.

[6] N. Rocha, J. A. F. Gamelas, P. M. Goncalves, M. H. Gil, J. T. Guthrie, European Polymer Journal 2009, 45, 3389.

[7] N. Rocha, "Interactions in Composite Polymeric Materials - Influence on Application Properties", in Chemical Engineering Department, University of Coimbra, Coimbra, 2010, Ph.D. Thesis.

[8] J. Rodriguez-Hernandez, F. Checot, Y. Gnanou, S. Lecommandoux, Prog. Polym. Sci. 2005, 30, 691.

[9] N. Rocha, P. V. Mendonça, J. Góis, R. Cordeiro, A. Fonseca, T. Guliashvili, K. Matyjaszewski, A. Serra, J. F. J. Coelho, "The Importance of Controlled/Living Radical Polymerization Techniques in the Design of Tailor Made Nanoparticles for Drug Delivery Systems", in Drug delivery systems: advanced technologies potentially applicable in personalized treatments, Springer, 2012, ISBN 978 94 007 6009 7.

[10] N. Rocha, A. Serra, J. F. J. Coelho, "Development of stimuli-responsive hybrid nanoparticles for advanced coatings applications, based on an ABCD type block copolymer", in The Polymer Conference, University of Warwick, Coventry, United Kingdom, 2012.

[11] N. Rocha, P. V. Mendonça, J. P. Mendes, P. N. Simões, A. V. Popov, T. Guliashvili, A. C. Serra, J. F. J. Coelho, Macromolecular Chemistry and Physics 2012, early view.


Stephan Roche Catalan Institute of Nanotechnology Theoretical & Computational Nanoscience Group, Spain

[email protected]

Q u a n t u m T r a n s p o r t i n D i s o r d e r e d G r a p h e n e :

S c a l i n g P r o p e r t i e s a n d S p i n r e l a x a t i o n M e c h a n i s m s

This talk will focus on the presentation of transport properties in graphene-based-materials containing disorder or specific structural morphologies such as grain boundaries in polycrystalline samples. The used multiscale quantum transport methodologies combine state-of-the-art first-principles with real space order N tight-binding approaches, will be shown to enable in-depth analysis of charge (and spin) transport fingerprints of realistic models of defected graphene of interest for industrial applications. Here, we will explore the effect of grain boundaries in polycrystalline graphene limiting charge mobilities in large-scale materials used in transparent electrodes applications. We will also discuss the origin of spin relaxation in graphene which is currently a highly debated issue, with reported spin diffusion times about 1 nanosecond, that is three orders of magnitude lower than expected, whereas the nature of relaxation fluctuates between Elliot-Yaffet and Dyakonov Perel mechanism with no consensus and puzzling experimental features. All these issues also point towards revisiting the way such fundamental length scales are usually extracted in experiments (Hanle Measurements, two-terminal magnetoresistance), prior to the development of spin manipulation and revolutionary spin devices.

Group webpage: www.icn.cat/index.php/en/research/core-research/theoretical-and-computational-nanosience/overview


Juan José Sáenz Departamento de Física de la Materia Condensada and Centro de Investigación en Física de la Materia Condensada (IFIMAC), Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049 Madrid, Spain.

[email protected]

S c a t t e r i n g A s y m m e t r y a n d N o n - c o n s e r v a t i v e O p t i c a l

F o r c e s o n N a n o p a r t i c l e s

We will address some basic questions related to the light forces on small (Rayleigh) particles, which are usually described as the sum of two terms: the dipolar or gradient force and the scattering or radiation pressure force. The scattering force is traditionally considered proportional to the Poynting vector, which gives the direction and magnitude of the momentum flow. However, as we will show, when the light field has a non-uniform spatial distribution of spin angular momentum, an additional scattering force arises as a reaction of the particle against the rotation of the spin. This non-conservative force term is proportional to the curl of the spin angular momentum of the light field [1].

We will discuss the peculiar dynamics of gold and silver nanoparticles in the non-conservative force field of an optical vortex lattice [2]. Radiation pressure in the vortex field (arising in the intersection region of two crossed optical standing waves) plays an active role spinning the particles out of the whirls sites leading to a giant acceleration of free diffusion. Interestingly, we show that a simple combination of null-average conservative and non-conservative steady forces can rectify the flow of damped particles. We propose a “deterministic ratchet” stemming from purely stationary forces [3] that represents a novel concept in dynamics.

The unusual properties of the optical forces acting on particles with both electric and magnetic response will also be analyzed [4]. We will focus on nanometer-sized spheres of conventional semiconductor materials, like Silicon (Si) or Germanium (Ge), which have extraordinary electric and magnetic optical properties in the infrared-telecom range of the electromagnetic spectrum [5-7]. Recent experimental results on microwave scattering on loss-less subwavelength dielectric spheres will be discussed [8]

References

[1] S. Albaladejo, M. Laroche, M. Marqués, J.J.

Sáenz, Phys. Rev. Lett. 102 , 113602 (2009) [2] S. Albaladejo, M.I. Marqués, F. Scheffold, J.J.

Sáenz, Nano Letters 9, 3527 (2009). [3] I. Zapata et al., Phys. Rev. Lett. 103, 130601

(2009) [4] M. Nieto-Vesperinas et al. , Opt. Express 18,

1149 (2010) [5] A. Garcia-Etxarri et al., Opt. Express 19, 4815

(2011) [6] M. Nieto-Vesperinas, R. Gómez-Medina, J.J.

Sáenz, J. Opt. Soc. Am. A 28, 54 (2011) [7] R. Gómez-Medina et al., J. Nanophoton. 5,

053512 (2011); Phys. Rev. A 83, 033825 (2011); Phys. Rev. A 85, 035802 (2012).

[8] J.M. Geffrin, et al., Nat. Commun. 3, 1171 (2012).


M. Virumbrales, A. Moya, M.Rivero, V. Blanco, M.J. Torralvo and R. Sáez Puche Dpto. Química Inorgánica, Facultad Químicas, Universidad Complutense Madrid, Ciudad Universitaria 28040- Madrid, Spain.

[email protected]

S y n t h e s i s , c h a r a c t e r i z a t i o n a n d m a g n e t i c p r o p e r t i e s o f

Z n F e 2 O 4 s p i n e l n a n o p a r t i c l e s e n c a s e d i n p o r o u s m a t r i c e s

ZnFe2O4 in bulk ceramic form is known to crystallize with a normal spinel structure where the tetrahedral sites are occupied by the Zn2+ ions. The Fe3+ cations are located in the octahedral holes given rise to a very week Fe-O-Fe superexchange interactions showing a Néel temperature as low as 10K. However, many studies have been reported concerning nanosized ferrite nanoparticles exhibiting a very different magnetic behaviour, i.e. superparamagnetism. The onset of these magnetic properties has been accounted for the partially inverted spinel, where a small amount of Fe3+ are located in tetrahedral coordination causing the appearance of a new Fe(Td)-O-Fe(Oh) superexchange interactions which yields a net magnetization component and a remarkable increasing of the Néel temperature. To avoid the particle aggregation and to control the particle growth many attemps have been done to synthetise these ZnFe2O4 nanoparticles encased in different non-magnetic porous matrices (1,2). Under these conditions the magnetic properties can be modulated by controlling the particle size diminishing the interparticle interactions and the interactions with the matrices.

The aim of this work is minimize the interparticle interactions in order to evaluate the particle size effect on the magnetic properties of these nanoparticles. For this purpose different matrices have been used to encapsulate ZnFe2O4 nanoparticles. Moreover, different synthetic methods have been also used to study the influence of the synthesis conditions on size distribution and inversion degree on the resulting nanoparticles.

ZnFe2O4 nanoparticles were prepared by two different methods: i) solvothermal conditions at temperatures from 160 °C to 200°C for different times and using Zn(NO3)2.6H2O and Fe(NO3)3.9H2O solution as precursor and ii) thermal decomposition of ferrite precursors in a high boiling point solvent. In this last case, Zn(acac)2.6H2O and Fe(acac)3.9H2O

were used as precursors and phenyleter as solvent. Oleylamine, 1,2-hexadecanediol and oleic acid were used as stabilizing agents in order to protect the surface of the particles (Figure 1a, sample MZn3.5) and to control the growth.

The nanoparticles were also prepared encased in porous matrices: MCM-41 and TUD-1 types and amorphous silica. Aqueous solutions containing stoichiometric amount of Zn nitrate and Fe nitrate were infiltrated in MCM-41 and TUD-1 and the infiltrated materials were kept at room temperature for 24 hours and then, the solids were heated at 600°C during 2 hours. After this treatment, ferrite nanoparticles inside the porous networks of the matrices were obtained (Figure 1b-d, samples MC-FZ, MH-FZ and T-FZ). ZnFe2O4 nanoparticles embedded in amorphous silica were prepared by dissolving stoichiometric amount of Zn and Fe nitrates in ethanol and adding distilled water and tetraethylorthosilicate (TEOS) in a molar ratio TEOS/EtOH/H2O of 1:4:11.7. After a gelling period of 4 days, the silica precursor was polymerized and the metal nitrates are distributed in the silica network. The embedded nanoparticles were obtained after thermal treatment of the gel at temperatures from 500 °C to 1000 °C.

Representative TEM images corresponding to monodisperse ZnFe2O4 nanoparticles and nanoparticles embedded in different matrices are collected in Figure 1. From images corresponding to the nanoparticles free of matrix (Figure 1a) statistical analysis has been done by measuring about 100 particles and 3.5 nm has been obtained as mean particle size. In images 1b and 1c we can see nanoparticles with size of 1.2 nm-1.7 nm (1b) and 1.2 nm-2.5 nm (1c) inside the tubular channel of the MCM-41 matrix. Image 1d corresponds to ferrite nanoparticles (3-5 nm) inside the disordered mesopores of TUD-1 matrix.


Figure 2 show the ZFC and FC magnetic susceptibility versus temperature curves of different samples. The high values of susceptibility suggests that, in all cases, the nanoparticles behave as superparamagnetic above the blocking temperature (TB, see inset in Figure 2). The shape of the FC curve in the TB-5K temperature range and the high difference between the ZFC and FC susceptibility values at low temperature suggests that the interparticle interactions for all of the samples are not significant (3). Nanoparticles free of matrix, sample MZn3.5, presents susceptibility values higher those obtained for nanoparticles with similar size prepared by the solvothermal method (4). This fact together with the intensity ratio (220)/ (400) X-ray reflections, suggest that the inversion parameter is higher for sample MZn3.5. Moreover, the high values of coercive field at 5K (Hc,5k) for nanoparticles embedded in amorphous silica and in TUD-1 seems to be due to the mechanical stress imposed by the matrix (4). This matrix effect is less important for nanoparticles embedded in MCM-41 matrices. References

[1] L.A. García Cerda, S.M. Montemayor, J.

Magn.Magn. Mater., 294, 2005, e43. [2] N. Guskos, S. Glenis, G. Zolnierkiewicz, J. Typec,

P. Berczynski, A. Guskos, D. Sibera, U. Narkiewicz, Appl. Phys. Lett., 100, 2012, 122403.

[3] Verónica Blanco-Gutiérrez, Regino Sáez-Puche, María J. Torralvo-Fernández, J. Mater. Chem., 22, 2012, 2992.

[4] V. Blanco-Gutiérrez, María J. Torralvo-Fernández, R. Sáez-Puche, J. Phys. Chem. C, 114, 2010, 1789.

Figures

Figure 1: TEM micrographs of: (a) monodisperse ZnFe2O4 nanoparticles (sample MZn3.5) and embedded in (b, c) MCM-41 (samples MC-FZ, MH-FZ) and (d) TUD-1 (sample T-FZ) matrices.

Figure 2: ZFC and FC magnetic susceptibility curves measured at 500 Oe.


Verónica Salgueiriño, N. Fontaíña-Troitiño, R. Otero-Lorenzo Dpto. Física Aplicada, Universidade de Vigo, 36310, Vigo, Spain

[email protected]

H y b r i d N a n o s t r u c t u r e s a s s e m b l i n g A n t i f e r r o - a n d

F e r r i m a g n e t i c O x i d e s

Interfaces between different oxides in hybrid systems offer the perfect environment for manipulating the complex interplay between the electronic and lattice degrees of freedom and drawing out new functionalities by exploiting epitaxial strain, local symmetry breaking, frustration or charge transfer between the materials. Magnetic interfaces are highly relevant for technological applications and in most of them, exchange bias plays a key role [1]. We intend to exploit oxide interfaces established in composite nanostructures synthesized by colloidal chemistry methods. The great advantage of using different types of inorganic nanostructures as

building blocks comes from the fact that permits the design and fabrication of colloidal and supracolloidal assemblies knowing first their magnetic characteristics. As a proof of concept we have developed mixed systems, driving on the surface of AFM substrates (goethite nanorods or cobalt oxide octahedrons), cobalt ferrite nanoparticles or magnetite shells (the study of bimagnetic systems opens new degrees of freedom to tailor the overall properties and offers the Meiklejohn-Bean paradigm) [2, 3]. Opposite structures driving the antiferromagnetic material on a ferrimagnetic substrates is also possible to attain.

References

[1] M. Gibert, P. Zubko, R. Scherwitzl, J. Iñiguez, J. M. Triscone, Nature Materials, 11, 195 (2012). [2] R. Mariño-Fernández, S. H. Matsunaga, N. Fontaíña-Troitiño, M. P. Morales, J. Rivas, V. Salgueiriño, J.

Phys. Chem. C 115, 13991 (2011). [3] Nerio Fontaíña-Troitiño, Beatriz Rivas, B. Rodríguez-González, V. Salgueiriño, in preparation (2013).

Figures

Figure 1: TEM image of antiferromagnetic CoO octahedral to be assembled in the final hybrid nanostructures.


Josep Samitier IBEC – Institute for Bioengineering of Catalonia, C/Baldiri Reixac, 10-12, 08028 Barcelona, Spain Centro de Investigación Biomédica en Red en Bioingeniería Biomateriales y Nanomedicina (CIBER-BBN), C/María de Luna 11, Edifi cio CEEI, 50018 Zaragoza, Spain Department of Electronics University of Barcelona, C/Martí i Franquès 1, 08028 Barcelona, Spain

[email protected]

F u n c t i o n a l l i p o s o m e a r r a y s b a s e d o n n a t u r a l n a n o v e s i c l e s

Natural vesicles produced from genetically engineered cells with tailored membrane receptor composition are promising building blocks for sensing biodevices [1]. This is particularly true for the case of G-protein coupled receptors (GPCRs) present in many sensing processes in cells, whose functionality crucially depends on their lipid environment. However, the controlled production of natural vesicles containing GPCRs and their reproducible deposition on biosensor surfaces are among the outstanding challenges in the road map to realize practical biomolecular devices based on GPCRs.

Dealing with membrane receptors is challenging due to the fact that they are difficult to produce, in comparison with other biomolecules, such as, for instance, soluble proteins or oligonucleotides. Besides, their activity on a substrate depends crucially on their orientation and functional conformation, which is largely determined by the lipid membrane environment fundamental to retain their tertiary structure and functional integrity. Current strategies developed for biosensing applications with membrane receptors include immobilization into supported lipid bilayers or into lipid vesicles (liposomes), made from artificial [2] or native membranes [3] as well as their inclusion into free-standing lipid bilayers lying on nanoporous substrates [4]. Isolation of native membrane fractions from a cell source, which integrate membrane receptors artificially expressed in the cell line, constitutes one of the preferred approaches as it provides the same lipidic environment found in the native cell, thus preventing the protein

denaturation during the insertion into an artificial membrane. The development of practical bio-molecular devices based on membrane receptors integrated in native membrane fractions requires, among other aspects, a strict control of the relevant parameters determining the membrane fraction characteristics and the surface coverage achievable under practical conditions, as well as, of the integrity and morphology of the deposited membrane receptors containers. Such information is al-most absent in the current literature. We pre-sent the production and characterization of membrane nanovesicles containing heterologously expressed olfactory receptors - a member of the family of GPCRs - and study their deposition onto substrates used as bio-sensor supports [5,6]. References

[1] M.Bally,K.Bailey,K.Sugihara,D.Grieshaber,J.Voro

s,B.Stadler Small 2010,6, 2481-2497 [2] M. Tanaka, E. Sackman, Nature 2005, 437, 656. [3] N. J. Wittenberg, H. Im, T. W. Johnson, X. Xu, A.

E. Warrington, M. Rodriguez, S.-H. Oh, ACSNano 2011, 5, 7555.

[4] E. Reimhult and K. Kumar, Trends in Biotechnol. 2008, 26, 82.

[5] J. Minic, J. Grosclaude, J. Aioun, M.-A. Persuy, T. Gorojankina, R. Salesse, E. Pajot-Augy, Y. Hou, S. Helali, N. Jaffrezic-Renault, F. Bessueille, A. Errachid, G. Gomila, O. Ruiz, J. Samitier, Biochim. Biophys. Acta 2005, 1724, 324.

[6] A Calò, P. Iavicoli, M. Sanmartí1, G. Gomila, J.Samitier, Soft Matter To be published 2012.


D. S. Schmool1, F. J. T. Gonçalves1, 5,

A. Apolinário1, N. de Sousa2, N. A. Sobolev3, F. Casoli4, F. Albertini4, P. Lupo4, R. L. Stamps5 and C. Hu5 1IFIMUP-IN, Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Portugal 2Dep de Física de la Materia Condensada, UAM, Spain 3Dep de Física and I3N, Universidade de Aveiro, Portugal 4IMEM – CNR, , Italy 5School of Physics and Astronomy, Univ of Glasgow, UK

[email protected]

M o d e l i n g e x c h a n g e – s p r i n g l a y e r e d s y s t e m s w i t h

p e r p e n d i c u l a r a n i s o t r o p y u s i n g f e r r o m a g n e t i c

r e s o n a n c e m e a s u r e m e n t s

Exchange – spring magnets are composite materials, which exploit the magnetic properties of two ferromagnetic materials, which are exchange coupled. We consider the system of a hard magnetic layer with perpendicular anisotropy (FePt in the L10 phase) coupled to a soft magnetic layer (Fe or Fe3Pt). The main interest for such a system is the reduction of the reversal field for the hard magnetic layer via the introduction of a 90° domain wall in the plane of the sample, which can propagate through to the hard layer and initiate the switching process via a reversible mechanism. Additionally, the system maintains good thermomagnetic stability and is an excellent candidate for perpendicular magnetic recording media.

We have experimentally studied the FePt/Fe3Pt bilayer system using ferromagnetic resonance at room temperature. Measurements were taken as a function of the direction of the applied external magnetic field. Results show that the effect of exchange coupling is manifest by the induction of a strong perpendicular anisotropy into the soft layer (Fe3Pt) from the hard layer (FePt). We have used the angular variation of the resonance field to allow us to assess the anisotropy constants for three different thicknesses of the soft layer (2, 3.5 and 5 nm). We observe a decrease of the overall perpendicular anisotropy as the soft layer thickness increases. We note that the hard layer does not contribute to the spectra under the experimental conditions used (9.3 GHz, magnetic fields up to 1T). We have developed a model of the exchange – spring bilayer type system, which consists of a variable exchangeinduced anisotropy through the soft layer. Our model system is the magnetic bilayer FePt (hard)/Fe(soft). Building on previous theoretical work [1], we have adapted the anisotropy constant

of the soft layer to be a variable parameter of position in the soft layer, thus giving a profile of K(tFe). The model was developed in order to simulate the experimentally obtained variation of the Fe top layer spin orientation in an exchange coupled FePt/Fe bilayer system with varying Fe thickness [2]. In figure 2 we show the results of the model (open circles) and a comparison to the experimental variation of top Fe layer spin orientation (black squares). Also shown are the variations for fixed values of the soft layer anisotropy; note that for the purposes of the calculations, the anisotropy constant has been normalized with the exchange constant of the hard layer. As will be seen from figure 1 the values of the position sensitive anisotropy fit exactly to the experimental values allowing us to obtain the variation K(tFe). This variation is shown in figure 3 (black squares). The value of the FePt surface anisotropy is also given (red point) and is consistent with the anisotropy variation. As shown in the figure, the magnetic anisotropy of the soft layer appears to vary most strongly from tFe = 2 – 4 nm, being essentially constant for greater thicknesses. Additionally, in this figure we show the soft layer averaged anisotropy as a function of its thickness on the hard layer.

The model we have presented is consistent with our FMR data on the FePt/Fe3Pt samples as is seen from the comparison of the variations of the anisotropy constants of the soft layers shown in figures 1 and 3. We note that the layer-averaged value of the anisotropy is expected to agree with the FMR measurements since this technique essentially measures the overall magnetic properties of the film and is not sensitive to variations within the layer itself.


References

[1] N. de Sousa, A. Apolinario, F. Vernay, P. M. S.

Monteiro, F. Albertini, F. Casoli, H. Kachkachi and D. S. Schmool, Phys. Rev. B 82, 104433 (2010).

[2] B. Laenens, N. Planckaert, J. Demeter, M.

Trekels, C. L’abbé, C. Strohm, R. Rüffer, K. Temst, A. Vantomme, and J. Meersschaut, Phys. Rev. B 82, 104421 (2010). Am. Chem. Soc., 133 (2011) 20914-20921.

Figures

Figure 1

Figure 2


Maria João Silva, Ana Tavares, Susana Antunes, João Lavinha, Henriqueta Louro Departamento de Genética Humana, Instituto Nacional de Saúde Dr. Ricardo Jorge (INSA), Lisboa, Portugal

[email protected]

S a f e t y e v a l u a t i o n o f m a n u f a c t u r e d n a n o m a t e r i a l s :

c o m p a r i s o n o f g e n o t o x i c e f f e c t s o f m u l t i - w a l l e d c a r b o n

n a n o t u b e s i n t w o h u m a n c e l l l i n e s

Nanotechnologies are developing very rapidly and presently, nanomaterials are increasingly used in a wide range of applications in science, industry and biomedicine. While a lot of effort has been put in the development of new manufactured nanomaterials (NMs) and in many innovative applications of nanothecnologies, comparatively less research has been performed to evaluate their safety for humans and the environment. Sound information about hazard is lacking for the vast majority of nanomaterials, especially related to chronic exposure to low doses that is likely to occur through consumer products. The genotoxic effects of NMs, which may be linked to carcinogenic effects, are of special concern because cancer has a long latency period; thus, these late effects can be less obvious and more difficult to predict than the acute effects.

Multi-walled carbon nanotubes (MWCNT) are NMs that have been widely applied in structural composites, energy appliances and electronics [1]. The same physicochemical properties that have rendered them attractive for those purposes might also underlie relevant biological effects with impact on human health and the environment. Size, surface properties, agglomeration state, biopersistence and dose are likely to influence cell responses to MWCNT, presenting a challenge to the assessment of their potential hazards. In particular, the similarity, in size and shape, between MWCNTs and asbestos fibers has raised concerns about their potential genotoxic and carcinogenic effects. The potential genotoxic effects of several MWCNT have been characterized in vitro and in vivo, but discrepant results have been reported, showing either absence [2,3] or induction of genomic instability [4-7]. These inconsistent results may be related to differences in the physicochemical properties of the NMs studied and to other variables inherent to the in vitro test systems and exposure conditions. Therefore, the use of standardized

methods and well characterized NMs has been recommended, to allow the comparison of the genotoxic effects obtained for a given NM in different laboratories or the genotoxic potential of several NMs [8].

In the context of an EU Joint Action (NANOGENOTOX), aimed at establishing a robust methodology for the safety evaluation of the manufactured nanomaterials, the objective of the present work was to compare the potential genotoxic effects of two thin and short MWCNT (NM-402 and NM-403; JRC repository) in a human type-II alveolar epithelial cell line (A549 cells) and in primary human lymphocytes.

Dispersions of each NM were freshly prepared according to a standardized protocol [9] and cells were exposed to several NMs concentrations. Concurrent control cultures were also analyzed: vehicle control, positive and nanosized controls (mitomycin C and ZnO, respectively). The in vitro micronucleus assay, a validated method accepted for regulatory purposes [10], was selected to assess chromosome structural and numerical changes.

Considering alveolar cells exposure to NM-402, a dose-response relationship was obtained for the frequency of micronucleated cells with the two highest concentrations being able to significantly increase the frequency of micronuclei, comparatively to the vehicle control. However, equivocal results were obtained in lymphocytes, with a single concentration yielding micronuclei induction. In contrast, NM-403 failed to produce micronucleation in alveolar cells but was able to significantly induce micronuclei in lymphocytes at the same dose-range. Positive controls yielded positive results in both cell types.

In conclusion, a differential response was observed for two closely related MWCNT in two human cell


systems, which might be explained by differences in the uptake capacity or sensitivity of the tested cell types or by structural differences of MWCNT, including surface activity and transition metals present as impurities. This study illustrates the difficulty of implementing hazard-grouping strategies based on the similarity of the NMs physicochemical properties and hypothesized mode of action. It highlights the importance of investigating the toxic potential of each NM individually until the main characteristic(s) that determine NMs genotoxicity is(are) uncovered. Most of all, interconnections between the pace of technological change and safety has to be guaranteed, in order to benefit from innovation while protecting public health and the environment.

Co-funded by EU Grant Agreement 2009 21 01 (NANOGENOTOX), in the framework of the EU Health Programme and INSA.

References

[1] Wijnhoven, S.W.P., Dekkers, S., Hagens, W.I., de

Jong, W.H., 2009. RIVM Letter Report 340370001/2009.

[2] Asakura, M., Sasaki, T., Sugiyama, T., Takaya, M., Koda, S., Nagano, K., Arito, H., Fukushima, S., J Occup. Health 52 (2010) 155-166.

[3] Szendi, K., Varga, C. Anticancer Res. 28 (2008) 349-352.

[4] Cveticanin, J., Joksic, G., Leskovac, A., Petrovic, S., Sobot, A.V., Neskovic, O., Nanotechnology 21(2010), 015102.

[5] Di Giorgio, M.L., Di Bucchianico, S., Ragnelli, A.M., Aimola, P., Santucci, S., Poma, A. Mutat. Res. 722 (2011) 20-31.

[6] Guo, Y.Y., Zhang, J., Zheng, Y.F., Yang, J., Zhu, X.Q. Mutat. Res. 721 (2011)184-191.

[7] Lindberg, H.K., Falck, G.C., Suhonen, S., Vippola, M., Vanhala, E., Catalán, J., Savolainen, K., Norppa, H. Toxicol. Lett. 186 (2009) 166-173.

[8] Oesch, F., Landsiedel, R., Arch. Toxicol. 86 (2012) 985-994.

[9] Jensen, K.A., Kembouche, Y., Christiansen, E., Jacobsen, N.R., Wallin, H., Guiot, C., Spalla, O., Witschger, O. NANOGENOTOX deliverable report n°3 (2011). Available at: www.nanogenotox.eu.

[10] OECD - Organisation for Economic Co-operation and Development. OECD guideline for the testing of chemicals. Guideline 487 (2010).


Nuno Silvestre1, Bruno Faria1 and

José N. C. Lopes2 1Department of Civil Engineering and Architecture, ICIST Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisboa, Portugal 2Department of Chemical and Biological Engineering, CQE Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisboa, Portugal

[email protected]

M e c h a n i c a l b e h a v i o u r o f t e n s i o n e d a n d t w i s t e d c h i r a l

c a r b o n n a n o t u b e s

It is well known that CNTs are sensitive to compression, bending and torsion, due to their hollow configuration. Concerning the compressive behaviour, it is now well understood that CNTs are prone to both local and global instability. Molecular dynamics (MD) simulations have shown that the buckling behaviour of a given CNT is length dependent and may be divided into two categories: (i) the shell-like instability (local buckling) for short to intermediate length, and (ii) the beam-like instability (global buckling) for moderate to long lengths. For CNTs with short to intermediate length, the critical strain is not sensitive to the length, while for long CNTs the critical strain depends on the length. For a given CNT structure (n,m), it is also clear that there is an aspect ratio value (length over diameter) that separates the range of local instability from the range of global instability. On the other hand, CNTs under torsion are always sensitive to local instability and the critical twist angle always decreases with increasing length [1]. The first objective of this paper is to shed light on the strength and stiffness of chiral CNTs under torsion, but now combined with tension. The second main goal is to investigate the kinematics of bonds between carbon atoms and its evolution with the applied loading. In order to assess the collapse behaviour of chiral CNTs, MD simulations of twisted and tensioned CNTs are performed. The LAMMPS code is used, the Tersoff-Brenner potential is considered for C-C bonds, the temperature is kept in 300 K and the incremental displacements u and rotations θ are imposed in CNT ends. The results are shown in the form of interaction (εul-αcr) diagrams, where εul=uul/L is the ultimate tension strain and αcr=φcr/L is the critical angle of twist per unit of length. After that, some

relevant conclusions are drawn concerning the most influential loading on the chiral CNT collapse: twisting over strain or strain over twisting. Then, an interaction formula based on analytical expressions of continuum mechanics is proposed and its results are compared with those obtained from MD simulations. After this study, special attention is devoted to the evolution of C-C bond lengths and angles with the applied loading, which explains the distinct mechanical behaviour of chiral CNTs and shed light on the anisotropic constitutive law of chiral CNTs. Finally, it is shown that buckled CNTs stiffness and strength does not cease beyond first buckling.

For illustration purposes, Figure 1 shows a set of four snapshots of the chiral (6,3) CNT under several twist-to-tension ratios: pure tension (1st snapshot), combination A with twist-to-tension ratio Δφ/Δu=0.349 rad/Å (2nd snapshot), combination B with twist-to-tension ratio Δφ/Δu=0.605 rad/Å (3rd snapshot), pure twisting (4th snapshot). Figure 1(a) presents the initial (unloaded) configuration of the CNT while Figures 1(b), 1(c), 1(d) and 1(e) present the deformed shapes of the CNTs after 100, 200, 300 and 400 increment, respectively. The Figures in the left side (1(b1), 1(c1), 1(d1), 1(e1)) involve direct twisting of the CNT while the Figures in the right side (1(b2), 1(c2), 1(d2), 1(e2)) involve inverse twisting of the CNT. From this Figure, it is observed that the CNT degradation and the evolution of its collapse is totally different if the CNT is under direct or inverse twisting. For combinations A (0.349 rad/Å – 2nd snapshot) and B (0.605 rad/Å – 3rd snapshot), the CNT also behaves differently for direct and inverse twisting – for instance, see the 2nd snapshot in Figures 1(d1) and (d2). The


tensioned CNT under direct twisting (combination A) tends to buckle into an helix-shape at early stages (200 increments - Figure 1(c1)) without rupture. A clear rupture is visible only at 400 increments (Figure 1(e1)). The tensioned CNT under inverse twisting (combination A) does not tend to buckle into an helix-shape and shows a localized rupture at an early stage (200 increments - Figure 1(c2)). For combination B, a similar behaviour is observed, but the CNT collapse occurs earlier for both direct and inverse twisting.

References

[1] Faria B., Silvestre N., Canongia Lopes J.N. –

“Interaction diagrams for carbon nanotubes under combined shortening-twisting”, Composites Science and Technology, 71 (2011), 1811-1818.

Figures

Figure 1: Deformed shapes of the CNT under tension-to-twist rates: (a) initial (unloaded), (b) after 100 increments, (c) after 200 increments, (d) after 300 increments and (e) final (after 400 increments) - (b1), (c1), (d1), (e1) for direct twisting and (b2), (c2), (d2), (e2) for inverse twisting.


C. Simao1, N. Kehagias1, B.

Kosmala2,3, M. Salaun4, M. Zelsmann4, M. A. Morris2,3 and Clivia M. Sotomayor Torres1,5,6 1Institute Catalan of Nanotechnology, Campus de la UAB, Barcelona 08193, Spain 2School of Chemistry and the Tyndall National Institute, UCC, Cork Ireland 3Centre for Research on Adaptive Nanostructures and Nanodevices, Trinity College Dublin, Ireland 4Laboratoire des Technologies de la Microelectronique (CNRS), Grenoble 38054, France 5Catalan Institute of Research and Advanced Studies (ICREA), Barcelona 08010 , Spain 6Physics Department, Universitat Autònoma de Barcelona, Campus de la UAB, 08193 Bellaterra, Spain

[email protected]

B l o c k c o p o l y m e r s d i r e c t e d s e l f - a s s e m b l y d i r e c t e d b y

n a n o i m p r i n t : a p p r o a c h e s a n d n a n o m e t r o l o g y

Block-copolymers (BCP) are playing an important role in alternative lithographies to obtain sub-50 nm nanostructures on surfaces.[1] They are employed by a bottom-up approach based on BCPs microphase segregation on its constituent blocks originating cylinders or lamellas at the molecular scale. Top-down nanoimprint lithography (NIL) is an emerging technique to pattern features with sizes reaching sub 100 nm on surface in a large-area and in a reproducible manner [2] and has been explored as a tool to direct the self-assembly (DSA) of the BCPs. This combined top-down/bottom-up approach permits to subdivide the nanopatterns of the NIL stamp by 10 times, plus adding tunable molecular properties to the nanostructured surfaces. [3,4] The added value spans NIL field of applications to biotechnology,[5] energy conversion,[6] and nanoelectronics.[7] To achieve BCP DSA using NIL methodologies, the stamp features have to be commensurable with the BCPs periodicity (L0). Generally, BCP DSA is guided by higher values of blocks interaction parameter (Χn) which is known to give more ordered microphase domains, where Χn is inversely proportional to the temperature.[8] Here we report solvent vapors assisted nanoimprint lithography (SVANIL) to combine bottom-up and NIL.[3] A novel SVANIL setup able to imprint up to 4” wafers (Figure 2) was fabricated. Different molecular weights of BCPs PS-b-PEO and PS-PDMS were employed replicating the NIL stamp with high resolution. Moreover, microphase segregation was observed with features

in the sub-20 nm size that exhibited different feature alignment as a function of the height of the mesas (Figure 2). Thus, our methodology permitted us to combine in one production step the NIL and the BCP DSA, using only milibar pressures and reducing to one third the nanofabrication time, when comparing BCPs with conventional annealing. Currently, we are working in the selective etching of the annealed, to test the fabricated sub-20nm features as lithographic masks. The order of the nanodots array was quantified according to our algorithm that uses the opposite partner method to analyse hexagonal packed structures.9 The research leading to these results has received funding from the European Union Seventh Framework Program ([FP7/2007-2013] project LAMAND under grant agreement n° [245565]) and by the Spanish Ministry for Science and Innovation (Plan Nacional de I + D + I (2008-2011) under contract no. FIS2009-10150). The contents of this work are the sole responsibility of the authors.


References

[1] Ouk Kim, S.; Solak, H. H.; Stoykovich, M. P.;

Ferrier, N. J.; de Pablo, J.J.; Nealey, P. F., Nature 424, (2003)411.

[2] S. Zankovych, T. Hoffmann, J. Seekamp, J.U. Bruch and C.M. Sotomayor Torres, Nanotechnol., 12(2001)91.

[3] Salaun, M.; Kehagias, N.; Salhi, B.; Baron, T.; Boussey, J.; Sotomayor Torres, C.M.; Zelsmann, M.; J. Vac. Sci. Technol. B: Microelectr. Nanom. Struct. 29(2011) 06F208-1.

[4] S. M. Park, X. Liang, B.D. Hartenck, T. E. Pick, N. Hiroshiba, Y. Wu, B.A. Helms and D.L. Olynick, ACS nano, 5 (2011) 8523.

[5] L.C. Glangchai, M. Caldorera-Moore, L. Shi and K. Roy, J. Controlled Release, 125 (2008) 263.

[6] K.S. Han, J.H. Shin, W.Y. Yoon and H. Lee, Sol. Energy Mater. Sol. Cells, 95 (2011) 288.

[7] E.L. Yang, C.C. Liu, C.Y.P. Yang, C.A. Steinhaus, P.F. Nealey and J.L. Skinner, J. Vac. Sci. Technol. B, 28 (2010)C6M93.

[8] F.S. Bates, Science, 251 (1991) 898. [9] W. Khunsin, A. Amann, G. Kocher-Oberlehner, S.

G. Romanov, S. Pullteap, H. C. Seat, E.P. O´Reilly, R. Zentel and C.M. Sotomayor Torres, Adv. Funct. Mater. 22 (9), 1812 (2012).

Figures

Figure 1: SVANIL workflow

Figure 2: SEM images of non-etched SVANIL imprints on PS-b-PEO on silicon shows large-area homogeneous replica of the 250 nm lines PDMS stamp (left), and imprinted lines evidende the directed self-assembly of the BCP, with microphase segregation of PEO cylinders in a PS matrix, where the cylinders orientation is a function of the stamp topography.


Ricardo Simöes1,3, Jaime Silva1,2,

Alexandre Correia1, Senentxu Lanceros-Mendez2 1Institute for Polymers and Composites - IPC/I3N, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal 2Center/Department of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal 3Polytechnic Institute of Cávado and Ave, Campus do IPCA, 4750-810 Barcelos, Portugal

M o d e l i n g t h e e l e c t r i c a l a n d m e c h a n i c a l p r o p e r t i e s o f

C N T / p o l y m e r n a n o c o m p o s i t e s

It is well known that the addition of carbon allotropes to a polymeric matrix affect its mechanical and electrical properties. The changes can be significant even at small weight fractions of the reinforcement. Among the carbon allotropes carbon nanotubes (CNT) have received considerable attention [1]. This is due to their aspect ratio that enables the production of conductive composites with a low weight fraction of reinforcement and also enabling an improvement in the composite’s mechanical properties.

In the work, a numeric model has been employed to investigate the mechanical and electrical properties of polymer/CNT nanocomposites material subjected to a deformation. To achieve a better understanding of phenomena occurring at the smaller scales, an electrostatic model is used [2] as well as the molecular dynamics (MD) method [3]. The two models are then coupled in an iterative procedure, enabling the prediction of the micro-scale constitutive response, which is related to the local microstructure. The electrostatic model is based on ‘‘hard-core’’ cylinders model and the prescribed conduction mechanism is hopping between nearest neighbours.

In this work, it is also demonstrated how the conductivity of a polymer/CNT composite changes with the applied stress to the composite, effectively providing the ability to simulate and predict strain-dependent electrical behaviour of CNT nanocomposites, and useful insights for tailoring the structure of active/smart materials for specific properties.

It is also shown that the mechanical behaviour of a computer generated material depends on the fiber length, their initial orientation in the polymeric matrix, and their concentration. The fiber concentration has a significant effect on the properties, with higher loadings corresponding to higher stress levels and higher stiffness, as could be expected from experimental work.

References

[1] Moniruzzaman M., Winey K I, Macromolecules,

39 (2006) 5194 [2] Silva J, Ribeiro S, Lanceros-Mendez S, Simoes R,

Composites Science and Technology, 71 (2011) 643

[3] Simoes R, Cunha A, Brostow W, Modeling and Simulation in Materials Science and Engineering, 14 (2006) 157


Damien Thompson Tyndall National Institute, University College Cork, Ireland

[email protected]

M o d e l l i n g a n d D e s i g n o f N a n o s t r u c t u r e d I n t e r f a c e s

In this talk I will discuss the difficulties in describing nanoscale physics and describe how computer simulations can aid experiments in the realization of nanostructured materials. I will present recent results on molecular modeling and design of nanostructured interfaces for technology applications. I will focus on self-assembled monolayer films on noble metals [1],

metal oxide [2] and graphene [3]. I will also describe recent combined experiments and simulations of dendrimer-wrapped gold nanoparticles [4]. These (ultra)thin films and single-molecule nanostructures are used in molecular devices and also have potential applications in health and energy (Figure 1).

References

[1] a) Nerngchamnong, N.; Li, Y.; Qi, D.; Jian, L.; Thompson, D.; Nijhuis, C.A. (2013) The Role of van der Waals Forces in the Performance of Molecular Diodes. Nature Nanotechnology, accepted. (b) Perl, A.; Gomez-Casado, A.; Thompson, D.; Dam, H.; Jonkheijm, P.; Reinhoudt, D.; Huskens, J. (2011). Gradient-driven motion of multivalent ligand molecules along a surface functionalized with multiple receptors. Nature Chemistry, 3, 317-322.

[2] O’Dwyer, C.; Gannon, G.; McNulty, D.; Buckley, D.N.; Thompson, D. (2012) Accommodating Curvature in a Highly Ordered Functionalized Metal Oxide Nanofiber: Synthesis, Characterization, and Multiscale Modeling of Layered Nanosheets. Chemistry of Materials, 24, 3981–3992.

[3] Long, B.; Manning, M.; Burke, M.; Szafranek, B.N.; Visimberga, G.; Thompson, D.; Greer, J.C.; Povey, I.M.; MacHale, J.; Lejosne, G.; Neumaier, D.; Quinn, A.J. (2012) Non-Covalent Functionalization of Graphene Using Self-Assembly of Alkane-Amines. Advanced Functional Materials, 22, 717–725.

[4] Thompson, D.; Hermes, J.P.; Quinn, A.J.; Mayor, M. (2012) Scanning the Potential Energy Surface for Synthesis of Dendrimer-Wrapped Gold Clusters: Design Rules for True Single-Molecule Nanostructures. ACS Nano, 6, 3007–3017.

Figures

Figure 1: Molecular simulations and fluorescence microscopy experiments can be combined to determine the structure, dynamics and energetics of the interface between a two-legged dendrimer molecule and a receptor-functionalised self-assembled monolayer on gold [1b].


J. M. Teixeira1, J. Ventura1, M. P.

Fernández-García1, J. P. Araujo1, J. B. Sousa1, P. Wisniowski2,3, S. Cardoso3, P. P. Freitas3 1IFIMUP and IN-Institute of Nanoscience and Nanotechnology, and Departamento de Fisica, Faculdade de Ciencias, Universidade do Porto, Portugal 2Department of Electronics, AGH University of Science and Technology, Poland 3INESC-MN and IN-Institute of Nanoscience and Nanotechnology, Portugal

[email protected]

S p i n - d e p e n d e n t t u n n e l i n g i n C o F e B - M g O m a g n e t i c t u n n e l

j u n c t i o n s

In the last two decades we assisted to a boom of new classes of magnetically engineered nanostructured devices, which are suitable for advanced magnetic sensors (ultra sensitivity and sub-μm dimensions) and the long envisaged universal magnetic memory, Magnetic Random Access Memory (MRAM). One of such devices is the magnetic tunnel junction (MTJ), which exhibit the so called tunnel magnetoresistive (TMR) effect. The most basic MTJ structure consists of two ferromagnetic (FM) materials separated by an insulator layer usually designated as barrier. The thickness of these layers can be made very thin, a few nanometers or less.

We will present a detailed study on the physics of the underlying mechanisms that affect the spin-polarized transport in sputtered MTJs, based on the CoFeB/MgO/CoFeB trilayer structure with thin barriers (≤ 1 nm). This system has been intensively studied aiming practical applications because of the high RT TMR, high breakdown voltages, reproducibility, appropriate resistance-area products and crystal growth considerations. We have successfully studied pinhole-free MgO MTJs for barrier thicknesses as low as 0.85 nm and exhibiting RT TMR values above 100%. We have studied the characteristics of these MgO MTJs as a function of temperature [1,2] (Fig. 1), bias voltage [3, 4] (Fig. 2), barrier thickness (0.75 − 1.35 nm) [5] and CoFeB free layer thickness (1.55 − 3.0 nm) [6]. We show the presence of perpendicular magnetic anisotropy in the MTJs with the thinnest fabricated free layer, resulting in a strong out-of-plane magnetization component in zero-applied field (H). Angular dependent measurements of the tunnel

conductance (G) and TMR (Fig. 3) display that a magnetic field range of ±150 Oe is sufficient to put the free layer magnetization perpendicular to the MTJ plane. References

[1] J. Ventura et. al. Phys. Rev. B 78, 024403 (2008). [2] J. M. Teixeira et al. J. Appl. Phys. 106, 073707

(2009). [3] J. M. Teixeira et al. Phys. Rev. Lett. 196601,

5294 (2011) [4] J. M. Teixeira et al. Appl. Phys. Lett. 100, 072406

(2012) [5] J. M. Teixeira et al. Appl. Phys. Lett. 96, 262506

(2010) [6] J. M. Teixeira et al. Phys. Rev. B 81, 134423

(2010)


Figures

Figure 1: Temperature dependence of the electrical conductance for selected MTJs with different free layer thicknesses. The solid lines are fits to the experimental data based on the direct elastic tunneling model.

Figure 2: Inelastic electron tunneling spectroscopy for magnetic tunnel junctions with different electrode thicknesses.

Figure 3: G(H) loops measured in the MgO MTJ with tfl = 1.55 nm and for different orientations of H. (b) TMR as a function of θ. Black line represent the calculated TMR(θ) dependence. The insets show the canted Mfl state of the MTJ discontinuous free layer and the angular orientations defined relatively to the MTJ out-of-plane axis.


A.S. Ramos1, A.J. Cavaleiro1, M.T.

Vieira1, S. Simões2, F. Viana2, M.F.

Vieira2 1CEMUC®, Department of Mechanical Engineering, University of Coimbra, R. Luís Reis Santos, 3030-788 Coimbra, Portugal 2CEMUC®, Department of Metallurgical and Materials Engineering, University of Porto, R. Dr. Roberto Frias, 4200-465 Porto, Portugal

[email protected]

R e a c t i v e n a n o m a t e r i a l s f o r n o n - c o n v e n t i o n a l a p p l i c a t i o n s

A few energetic nanolayered systems composed of materials with high negative heat of reaction have been investigated for joining applications. Relying on the rapid release of energy during the mixing of reactant layers, these nanomaterials show potential as localized heat sources. The deposition by magnetron sputtering allows reactive multilayer foils/films with equiatomic chemical composition and with controlled nanoscale modulation period (bilayer thickness) to be produced (figures 1 and 2).

Reactive multilayers are composed of tens, hundreds, or thousands of alternating individual nanolayers of reactants having a large negative enthalpy of mixing. For certain designs, these multilayers exhibit fast, high temperature reactions that could be ignited by an external energy source such as an electric spark or a mechanical load. Local heating initiates the reaction locally, releasing heat that drives the reaction forward. The reaction moves in a self-propagating wave.

For some years now, the heat released by the exothermic reaction in Ni/Al multilayer foils is being used to melt braze alloys, promoting joining [1,2]. In the reactive brazing process a free-standing reactive multilayer foil is placed between two solder alloys. Reactive multilayers can also be used to enhance the diffusion bonding process by taking advantage of the improved diffusivity and reactivity of the alternating nanolayers – reaction assisted diffusion bonding. Ti/Al and Ni/Al nanometric multilayer thin films have been successfully used to assist the diffusion bonding process of advanced materials, namely titanium aluminides [3-5]. The use of reactive nanomaterials as fillers allowed sound joints to be obtained at reduced temperature and/or pressure and/or bonding time (figures 3 and 4). The diffusion bonding process comes very close to the ideal indistinguishable joint, which

makes this process suitable for micro-sized components. The possibility of adapting multilayer thin films in order to enable direct joining without solder or braze alloys is also anticipated. In this non-conventional joining approach, joints are made by stacking two coated components facing each other. If the multilayer thin films reaction could be locally ignited, the coated parts stacked facing each other would be diffusion joined at room-temperature in any atmosphere or under vacuum without the need of external heat sources. The multilayer coated parts are stacked with the surface of the thin films facing each other and the joining process takes place after ignition. Besides the reactive multilayer thin films of the Ni-Al system (medium enthalpy of reaction), low (Ti/Al, Ni/Ti) and high (Pd/Al) reaction enthalpy multilayer thin films are also being developed to be used in joining applications [6-8]. Recently, NiTi shape memory alloys have been diffusion bonded to a Ti-6Al-4V alloy using Ni/Ti multilayer thin films as a filler nanomaterial. The multilayer thin films control the diffusivity and reactivity at the joining interfaces and could also act as a localised heat source. Moreover, the use of the reactive multilayer thin films made possible to avoid the liquid phase formation during joining and to reduce the temperature, pressure and time required to successful join the coated materials (figure 5). So far, the most promising reactive nanolayers for non-conventional joining applications are those from the Ni-Al system with intermediate modulation period (between 10 and 20 nm).

Joining is presented as an example of reactive nanolayers’ potential. However, the application field is not limited to joining. A whole new branch of opportunities is open up for this kind of nanomaterials.


References

[1] A. Duckam, S.J. Spey, J. Wang, M.E. Reiss, T.P.

Weihs, E. Besnoin and O.M. Knio, Journal of Applied Physics 96 (2004) 2336.

[2] X. Qiu and J. Wang, Sensors and Actuators A 141 (2008) 476.

[3] L.I. Duarte, A.S. Ramos, M.F. Vieira, F. Viana, M.T. Vieira and M. Koçak, Intermetallics 14 (2006) 1151.

[4] J. Cao, J.C. Feng and Z.R. Li, Journal of Alloys and Compounds 466 (2008) 363.

[5] S. Simões, F. Viana, M. Koçak, A.S. Ramos, M.T. Vieira, and M.F. Vieira, Materials Chemistry and Physics 128 (2011) 202.

[6] J. Noro, A.S. Ramos and M.T. Vieira, Intermetallics 16 (2008) 1061.

[7] A.S. Ramos, M.T. Vieira, J. Morgiel, J. Grzonka, S. Simões and M.F. Vieira, Journal of Alloys and Compounds 484 (2009) 335.

[8] A.S. Ramos and M.T. Vieira, Intermetallics 25 (2012) 70.

Figures

Figure 1: SEM micrograph of a Ni/Al nanofoil with 60 nm period.

Figure 2: TEM micrograph of a sputtered Ti/Al multilayer thin film with 20 nm period.

Figure 3: TEM micrographs of a TiAl joint processed at 900°C/ 50 MPa/ 1h using a Ti/Al multilayer thin film.

Figure 4: SEM micrograph of a TiAl/Inconel joint processed at 800°C/ 5 MPa/ 1h using a Ni/Al multilayer thin film.

Figure 5: TEM micrograph of a NiTi/Ti-6Al-4V joint processed at 850°C/ 5 MPa/ 1h using a Ni/Ti multilayer thin film.


J.G. Vilhena1,2, Elena T. Herruzo2, P.

Pou1, Pedro A. Serena2, Ricardo García2, Rubén Pérez1,3 1Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid Campus de Cantoblanco Madrid 28049, Spain, 2Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, Spain 3Lawrence Berkeley National Laboratory, Berkeley, California CA 94720

[email protected]

M o l e c u l a r d y n a m i c s s t u d y o f t h e I g G a d s o r p t i o n o n a

g r a p h i t e s u r f a c e

Immunoglobulin G (IgG) is the most abundant of the five classes of antibodies produced by the body, and is synthesized in response to invasions by bacteria, fungi, and viruses. IgG is a protein complex composed of four peptide chains arranged in a Y-shape (see fig.): two identical heavy chains and two identical light chains of antibody monomers. A better understanding of the adsorption of the IgG to solid surfaces would have a big impact on areas ranging from medicine to biochemical engineering [1,2]. The control of the IgG adsorption, from solutions of single proteins as well as from more complex mixtures, requires an understanding of the involved mechanisms.

One adequate surface model to investigate the adsorption properties of the IgG is the graphite surface. On one hand, pyrolytic graphite is used as an implant material [2], therefore the importance of the study of the bio-compatibility with the IgG; And on the other hand, it is well established [3] that the hydrophobic nature of graphite improves the adhesion of the Fc fragment of the IgG, which is a very suitable feature for bio-sensors since they are often based on the ability of IgG to bind a large variety of molecules in a highly specific way.

In order to have a detailed understanding of the mechanisms behind the adsorption of the IgG on graphite we have performed atomistic molecular dynamics (MD) simulations using AMBER’s force fields[4]. Experiments on protein adhesion typically use an AFM tip to force the protein toward the surface and then pull it of to measure force-distance curves. Therefore in this study in addition to free adsorption. Here we also report the forced adsorption of the IgG using steered MD to simulate

the action of an AFM pushing the IgG towards the surface.

The level of detail on our simulations allow us to address several open questions concerning protein adsorption. In particular we are able to determine the mechanisms behind the adsorption; In which conditions the protein denature what is the role of the water molecules in such process. Moreover we were able to determine the most favorable adsorption orientation of the IgG which in turn allows us to set up a strategy to control the IgG adsorption over HOPG. References

[1] Vladimir Hlady, et al; Curr. Opin. Biotechnol. 7

(1996) 72. [2] Winter M, et al; Chirurgie de la Main, 28 (2009)

158 [3] Buijs J, et al; Langmuir 12 (1996) 1605 [4] Cornell WD, et al; J. Am. Chem. Soc. 117 (1995)

5179


Figures

Figure 1: (left) IgG over a HOPG graphite surface. (right) Adsorbed Fab (it is represented by its secondary structure, as well as by a ball-stick model for the hydrophobic residues).

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6/4

Cover image: TEM image of antiferromagnetic CoO octahedral to be assembled in the final

hybrid nanostructures.

Credit: Verónica Salgueiriño (Universidade de Vigo, Spain)

Edited by

Phantoms Foundation

Alfonso Gomez 17

28037 Madrid - Spain

[email protected]

www.phantomsnet.net

Deposito legal / Spanish Legal Deposit:

Phantoms Foundation

Alfonso Gomez 17 28037 Madrid - Spain

[email protected] www.phantomsnet.net

Edited by

www.nanopt.org

Documents

nanoPT2013 abstract book