Review Article Molecular Imprinting for High-Added Value ...downloads.hindawi.com/journals/amse/2014/932637.pdf · F : Works published for molecular imprinted polymers term (data

Review ArticleMolecular Imprinting for High-Added Value MetalsAn Overview of Recent Environmental Applications

George Z Kyzas and Dimitrios N Bikiaris

Laboratory of Polymer Chemistry and Technology Department of Chemistry Aristotle University of Thessaloniki541 24 Thessaloniki Greece

Correspondence should be addressed to George Z Kyzas georgekyzasgmailcom

Received 26 January 2014 Accepted 11 February 2014 Published 7 April 2014

Academic Editor Margaritis Kostoglou

Copyright copy 2014 G Z Kyzas and D N Bikiaris This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

One of the most hot topics of recent research is the reuse of some compounds existing as pollutants in environment Thesecompounds (molecules ions complexes etc) are of high-added value and it will be ideal to selectively bind them with anyenvironmental application and reuse them in their initial or modified formThe latter can be achieved using molecular imprintingIn the present review article an overview of the recent attempts for the selective binding of some precious metals (ie gold silverand platinum) of high-added value is done using molecular imprinted polymers (MIPs) as materials The simplicity of their usetheir relatively low cost and the broad range of possible guest molecules (small organic molecules ions metals and also biologicalmacromolecules) have since led to the important development of molecular imprinting

1 Introduction

One of the most hot topics of recent research is the reuseof some compounds existing as pollutants in environmentThese compounds (molecules ions complexes etc) are ofhigh-added value and it will be ideal to selectively bind themwith any environmental application and reuse them in theirinitial or modified form The latter can be achieved usingmolecular recognition The ability to selectively recognizea target molecule in a vast pool of similar molecules isessential to biological and chemical processes This processis called molecular recognition and it is an event that occurseverywhere in nature It occurs when twomolecules are bothgeometrically and chemically complementary that is whenthey can both ldquofit togetherrdquo spatially and bind with each otherusing noncovalent forces including hydrogen bonds elec-trostatic interactions hydrophobic interactions and weakmetal coordination [1] Therefore a specific technology hasbeen bloomed and redesigned in the last 30 years which iscalledmolecular imprinting (MI)Thewhole process is basedon adsorption technology which is already one of the mostsuccessful techniques for pollutants removal [2ndash8]

MI is not a recent scienceThe earliest reports of imprint-ing go back to the early 1930s when a Soviet chemist Polyakov[9] prepared a number of silica gels and observed that whenprepared in the presence of a solvent additive the resultingsilica demonstrated preferential binding capacity for thatsolvent In 1955 a senior student of Linus Pauling Dickeyobserved that after removal of the ldquopatterningrdquo dye the silicawould rebind with the same dye in preference to the others[10] However in 1972 a step change in molecular imprintingoccurred when the group of GuenterWulff reported that theyhad successfully prepared a molecularly imprinting organicpolymer (MIP) [11] Wulff used what is now termed a ldquocova-lent approachrdquo to prepare an organic molecularly imprintedpolymer capable of discriminating between the enantiomersof glyceric acid The classical methods of covalent imprint-ing involve readily reversible condensation reactions suchas boronate ester [12] ketalacetal [13] and Schiff rsquos baseformation [14] to prepare template monomers Subsequentlythroughout the 1970s and 1980s Wulff rsquos group publishedextensively using this approach

The second major breakthrough in organic polymerimprinting occurred in 1981 when Arshady and Mosbach

Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2014 Article ID 932637 8 pageshttpdxdoiorg1011552014932637

2 Advances in Materials Science and Engineering

reported that they had prepared an organic MIP using non-covalent interactions only [15]This approach was termed theldquononcovalent approachrdquo as opposed to the covalent approachfavoured by Wulff and it was this approach with its simpleseemingly trivial methodology that triggered the explosionin molecular imprinting that occurred during the 1990sNoncovalent imprinting uses the typical forces of attractionbetweenmolecules such as hydrogen bonds ion pairs dipole-dipole interactions and van der Waals forces to generateadducts of template and functional monomers in solutionUnlike those used in covalent methods of imprinting theseadducts are unstable and dynamically rearrange on a timescale relevant to the imprinting process To this day thenoncovalent versus covalent debate continues with bothsides being championed However it is generally acceptedthat there are pros and cons to both approaches So in1995 Whitcombe et al reported an intermediate approachthat combines the advantages of both approaches [16] Thisapproach relies on covalent interaction during the polymer-ization stage but noncovalent interactions during rebindingImportantly in order to improve subsequent noncovalentbinding geometry Whitcombersquos approach incorporated asacrificial spacer group that was designed to be lost duringtemplate removal The noncovalent approach however is stillby far the most widely used approach in MIP synthesisSeveral of its drawbacks can be overcome by the use ofstoichiometrically associating monomer-template systems[17] This has resulted in a range of receptors exhibitinghigh capacity and effective recognition properties in aqueousmedia

The simplicity of use the relatively low cost and the broadrange of possible guest molecules (small organic moleculesions and also biological macromolecules) have since led tothe important development of this technique as illustratedby the increasing numbers of publications over recent years(Figure 1)

It is a great of interest to preparedesign materialswhich only selectively remove carcinogenic pollutants fromwastewaters as ions phenols and drugspharmaceuticalsNowadays MIPs are highly cross-linked polymeric phaseswith predetermined selectivity for a single molecule or agroup of structurally related molecules (template) employedin separation processes of environmental pollutants (chro-matography solid-phase extraction membrane separationsand adsorption) artificial antibodies and sensors recogni-tion elements [14]

This review aims to gather and report (i) recent synthesisroutes of MIPs and (ii) their environmental applications forldquohot pollutantsrdquo of high-added value metals discharged inenvironmental ways The novelty of this work is clear giventhe lack of review articles or overviews regarding the use ofMIPs for high-added valuemetals Scopus which is one of thelargest abstract and citation database of peer-reviewed worksgives 136 results after searching with terms as ldquoMolecularlyImprintedrdquo However none of them are special for metals (orprecious metals)

0

200

400

600

800

1000

1200

1400

1600

Pape

rs

2011

ndash2013

2001

ndash2010

1991

ndash2000

1981

ndash1990

1971

ndash1980

1961

ndash1970

1951

ndash1960

1900

ndash1950

Figure 1 Works published for ldquomolecular imprinted polymersrdquoterm (data after search in Scopus)

2 Design and Synthesis of MIPs

The preparation of MIPs starts by positioning the functionalmonomers around a template molecule The monomersinteract with sites on the template via interactions that canbe reversibly covalent or noncovalent (hydrogen ionic vander Waals 120587-120587 etc) Then they are polymerized and cross-linked around the template in order to fix their position andto ldquofreezerdquo the geometry of the pores in the network Thetemplate molecule is then extracted leaving a polymer withfunctional sites capable of molecular recognition

The first step is the contact between the functionalisedmonomers and the template molecule which leads to theformation of a complex Its structure and stability will thendetermine the behaviour of the future MIP The interactionsinvolved must be sufficiently strong to remain intact duringthe polymerisation stage but sufficiently labile to enabletemplate extraction and reinsertion of guest molecules in thelater stages These interactions must therefore occur rapidlyand be reversible It is crucial to optimise the choice of thedifferent components of the system at this point

Different types of strategies can be distinguished depend-ing on whether the bonding between template and host iscovalent or not (i) covalent interactions (ii) noncovalentinteractions and (iii) double approach covalent plus nonco-valent

The second step is the polymerisation step of themonomers around the complex formed in the first step [18]Owing to its ease of use radical polymerisation is the mostfrequent The crucial question is to determine how to carryout this polymerisationcross-linking step with minimumdisturbance of the complex already in place Choices mustbe made for instance in radical polymerization the radicalscan be generated at 60∘C (aa1015840-azobutyronitrile as initiatordenoted as AIBN) 45∘C (azobis valeronitrile as initiatordenoted as ABDV) which could cause heat destabilisation ofthe complex or at 4∘C with low-temperature photochemical

Advances in Materials Science and Engineering 3

radical production (AIBN 360 nm) Comparative studies onrecognition specificity have shown that the photochemicalapproach gives the most specific materials [19]

Another crucial point of the preparation of MIPs is theextraction step The proportion of extraction of the templatemolecules interacting with the MIP via easily hydrolysablecovalent bonds or noncovalent linkages is estimated to beabout 90 The remaining molecules are trapped in highlycross-linked zones This problem is exacerbated with macro-molecules where steric hindrance lowers the efficiency ofextraction In addition the synthesis of MIPs requires largequantities of guest molecule (50 to 500 120583moles per gram ofpolymer) So when pure template molecule is difficult orexpensive to obtain reaching quantitative template extrac-tion yields can be primordial Extraction conditions mustthen be optimised to obtain yields of over 99The extractionstep uses an appropriate solvent It often proves to be longand the actual process involved is dependent on the systemin question So automation of thewashing steps for industrialapplications still remains problematic Extraction of the tem-plate leaves a three-dimensional material in which the cavityshapes and functional group locations are complementary tothe guest molecule

Solvent plays an important role in the formation of theporous structure of MIPs which are a subset of a largerclass known as macroporous polymers The morphologicalproperties of porosity and surface area are determined bythe type of solvent referred to as ldquoporogenrdquo used in thepolymerization Many solvents were tested in the literaturefor the preparation of MIPs presenting their main differ-entiation in the phase The main organic solvents used aredimethyl sulfoxide (DMSO) dimethyl formamide (DMF)acetonitrile toluene and chloroform while deionized wateris also used as solvent [20] Moreover it is notable to bereported that a prepared MIP is composed typically of a 70to 98 of its final mass from cross-linker Numerous cross-linkers have been tested for the preparation of a rigid MIPas divinylbenzene (DVB) ethylene glycol dimethacrylate(EGDMA) ethylene bis aacrylamide (EBA) and trimethylpropane trimethacrylate (TRIM) The groups of Wulff et al[21] and Sibrian-Vazquez and Spivak [22] have systematicallystudied the effect of cross-linkers on the recognition proper-ties of MIPs

Another important point is that the synthesis is relatedto the template used For example the synthesis of MIP andthe binding forces between template and polymeric matrixcan be strongly influenced by the valence of the templateTherefore other reagents are selected in order to form apolymeric matrix for monovalent metal as templates andother for others

After the preparation of MIPs a full characterization isnecessary to examine the morphological and functionalizedproperties of the preparedmaterialsThe common techniquesof MIPs characterization are spectroscopy (NMR FTIR)swelling tests and BET analysis [17 23]

In summary a very characteristic schemeexample wasfound in the literature describing the synthesis and selectivebinding of dye molecules (as templates) with two typesof MIPs either for basic (Figure 2(a)) or reactive dyes

(Figure 2(b)) [24] Essentially two strategies for molecularimprinting have been established based on whether the tem-plate is associated with interactive monomers using covalentbonds or noncovalent interactions Of the two strategies thenoncovalent approach has been used more extensively forthree reasons (i) noncovalent methodology is easier becauseit does not require synthetic steps toward the prepolymercomplex and interactions between monomers and templateare easily obtained when all components are mixed insolution (ii) removal of the template is generally much easierand usually it is accomplished by continuous extraction (iii)a greater variety of functionalities can be introduced into theMIP binding site using noncovalent methods

Prior to its use in experiments an MIP is usuallyevaluated to check its recognition properties for a targetChromatographic evaluation and equilibrium batch rebind-ing experiments are the methods most commonly usedto investigate the selectivity of the imprinted materialsChromatographic evaluation allowsmeasurement of capacityfactors (1198961015840) and imprinting factors (IF) of MIPs These valuesare obtained from the retention time of the templatemoleculeon a chromatographic column packed with the MIP and asecond column packed with the NIP (nonimprinted polymerwhich is synthesized just the same as MIP but without thetarget compound) If the MIP is imprinted then the analyteshould be retainedmore strongly on theMIP than on theNIPbecause of the selective interactions In some studies [25]the selectivity of the MIP was also probed using compoundsstructurally related to the template If the MIP retains thesecompounds almost as well or better than the template thisindicates that the MIP shows cross-reactivity [25]

For equilibrium batch rebinding experiments a knownmass of template in solution is added to a vial containinga fixed mass of polymer Once the system has come toequilibrium the concentration of free template in solutionis measured and the mass of template adsorbed to the MIPis calculated [26] Some of these experiments are basedon radioligand binding which is a very highly sensitivemethod to study the population of binding sites with thestrongest binding characteristics [13] Typically the sampleis incubated with the radioligand for several hours and acentrifugation step is used to sediment the polymer particlesThe radioactivity in the supernatant is then measured

3 Selective Binding of High-AddedValue Compounds

Numerous studies have been reported regarding the imprint-ing of ions and the use as adsorbents for the selective cap-turebinding from environmental media Many ionsmetalshave been selectively bound from MIPs presenting impres-sively high selectivity coefficients

For example Tsukaghoshi et al [27] prepared imprintedmicrospheres using seeded emulsion polymerization of DVBstyrene butyl acrylate and methacrylic acid (MAA) Theimprinted structure was introduced on the carboxylatedmicrosphere by surface imprinting in which the carboxylgroups were reorganized through complexation with metal


N N

Cl

NO

N N

Cl

N

O

Remacryl red TGL (BR)(template)

MAA(monomer)

EGD

MA

(cross-linker)

C2H5CH2

CH2CH2

CH3

CH3

N+

O2NO2N

H2C

C2H5

N+

CH3

CH3

CH3

Clminus Ominus

H3CCH2CH2

CH3

CH3

N N

Cl

N

O

C2H5

N+

O2N

Ominus

H3CCH2CH2

CH3

CH3

HmdashO

minusTemplate+Template

pH 10

OOminus

(a)

O

O

AA

m

NN

OH

S S

HN

N NCl

N NH

SO

OO S

O

OONa

ONa

O

O O

O ONa

SO

OSO

ONaO

NaO

NN

OH

S S

HN

N NCl

N NH

SO

OO S

O

OO

O

OO

O

O O

SO

OOS

O

OO

OO

O

O

O

Remazol brilliant red 3BS

MBA

minusTe

mpl

ate

+Te

mpl

ate

pH2

(template)

(monom

er)

CH2

CH2

H2N

NH3

H3C

C

OC

OC

OC

H2C

(cross-linker)CH2H3N

H3N

NH3

NH3

H2CH2C

NH3

OC

NH3

H3N

H3N

H3N

OC

NH3

O

OO

OS

CH3N

N N

NCl

N

NHN

OC NH3

OC

H3N

OCH3N

O3S

SO3 SO3

SO3

O3S

OHHN

(b)

Figure 2 Schematic representation of the imprinting process for (a) basic and (b) reactive dye


ions on the surface and then fixed in their specific orientationby cross-linking polymerization The imprinted effects wereverified on Cu(II)- Ni(II)- and Co(II)-imprinted micro-spheres Furthermore in another work [28] monomer-typefunctional surfactants (2-(p-vinyl benzylamino)-alkanoicacid and NN-dialkyl derivatives) have been used as bothligand and emulsifier for the preparation of surface-templateresins The surfactants were adsorbed at the toluene-waterinterface and emulsified DVB-styrene in a Cu2+ or Zn2+solution Emulsion polymerization using a K

2S2O8initiator

(80∘C) or by irradiation with gamma-rays gave particles of200ndash800 nm in diameter Both resins showed an imprintingeffect for Cu or Zn respectively Another brief example wasgiven by Chen and coworkers [29] who synthesized 4-vinylbenzyl-substituted 147-triazacyclononane (TACN) ligand bytreating 1 or 3 moles of 4-vinyl benzyl chloride with TACNand formed complexes with zinc The copolymerization ofZn2+ complexes with the cross-linking agent DVB (80) andthe use of AIBN as initiator provided highly cross-linkedmacroporous polymers However attempts to prepare a CuIIP or a blank polymer were unsuccessful The overall orderof metal-ion selectivity for Zn2+ as the imprint ion MIPs isMn2+ lt Ni2+ lt Zn2+ lt Co2+ ⋘ Cu2+ which somewhatbut not exactly follows the Irving-Williams order of stabilityChen et al [29] have postulated that Zn2+ imprinting (theionic radius of Zn2+ and Cu2+ being comparable) accountsfor the selectivity for the Cu2+ ion over the Fe3+ ion becauseusually the Fe3+ ion can readily compete for any polymer-pendant ligand site because of its favorable charge-to-radiusratio

Ca2+- and Mg2+-ion-selective sorbents were preparedby ion imprinting using NN1015840-dimethyl-(NN1015840-bis-4-vinylphenyl)-3-oxapentane diamide then they were used as theion-complexing monomerThe resulting polymers were ana-lyzed for their ability to extract calcium ions frommethanolicwater The polymers prepared against Ca2+ and Mg2+ ionswere found to bind Ca2+ ions with 6 and 17 times lower119870diss values (constant of dissociation) respectively whencompared with reference polymers prepared in the absenceof metal ions In addition the number of binding sites forCa2+ ions determined for the respective polymer prepara-tion fitted well with theoretical values calculated from thestoichiometry of the complexation of the ionophore by Ca2+and Mg2+ ions respectively

The range of metal ions imprinted in organic polymersnow includes uranium (as UO

2

2+) [30] erbium [31] dys-prosium [32] gadolinium [33] cadmium [34] and lead [35]among others

However the most interesting is a new type of worksregarding precious metals as gold (Au) silver (Ag) andplatinum (Pt) which are characterized as being of high-added value The above metals have long been valued asprecious metals used in currency coins making ornamentsjewelry high-value tableware and utensils (hence the termsilverware) and as an investment in the forms of coinsand bullion They are used industrially in electrical contactsand conductors in mirrors and in catalysis of chemical

reactions Their compounds are used in photographic filmand other metal compounds are used as disinfectants andmicrobiocides (oligodynamic effect) While many medicalantimicrobial uses of the aforementioned precious metalshave been supplanted by antibiotics further research intoclinical potential continues

Ahamed et al [36] synthesized a novel chelating ion-imprinted resin using chitosan as a scaffold material N-ethylenediamine (1-imidazolyl ethyl)-type chitosan has beenprepared and applied to the selective extraction of gold(III)chlorides from complex aqueous solutions Batch adsorp-tion experiments were carried out with various parameterssuch as contact time pH initial Au(III) concentration andtemperature The kinetic studies revealed that the adsorptionprocess could be described by pseudo-second-order kineticmodel while the adsorption data correlated well with theLangmuir and Temkin models The maximum adsorptioncapacities calculated from the Langmuir equation are 81067and 64935mgg at pH 3 and 6 respectively The selec-tivity study revealed that the ion-imprinted polymer washighly selective to Au(III) compared to Pb(II) Ni(II) Cu(II)Mn(II) and Fe(III) even at the optimum binding pH for theother metal ions (pH 5-6) The adsorbent was successfullyregenerated with a 07M thiourea-2M HCl solution

Another research team [37] developed an ion-imprintedpolymer for selective extraction and determination of goldions To increase the adsorbent efficiency this polymerwas coated on a novel nanoporous carbon-based materialcarbohydrate-derived Max-Planck Gesellschaft 1 which isalso the first example of grafting imprinted polymer onnanoporous-carbon material These particles were appliedsuccessfully for preconcentration of ultratrace amount of goldions following determination by flame atomic absorptionspectrometry Some effective factors on the efficiency of goldions extraction such as concentration and volume of eluantsample and eluant flow rates and also effect of interfering ionsespecially palladium and platinum ions were investigatedThe technique was also used to determine the concentrationof gold ions in mine stone samples with satisfactory resultsThe accuracy of this method was investigated by determina-tion of gold ions concentrations in several referencematerialswith certified gold content

The same research team but in another work [38] devel-oped a gold ion-imprinted polymer (GIP) by incorporatinga dipyridyl ligand into an ethylene glycol dimethacrylatematrix which was then coated onto porous silica particlesThematerial was used for the selective extraction of ultratracequantities of gold ion from mine stones this was followedby its quantitation by FAAS Similarly as above the effects ofconcentration and volume of eluant pH of the solution flowrates of sample and eluant and effect of potentially interferingions especially palladium and platinum were investigatedIn order to show the high selectivity and efficiency of thenew sorbent the results were compared to those obtainedwith more simple sorbents possessing the same functionalgroupsThe accuracy of themethod was demonstrated by theaccurate determination of gold ions in a certified referencematerial To the best of our knowledge there is no report so


far on an imprint for gold ions that has such a selectivity overPd(II) and Pt(II) ions

Furthermore another gold-imprinted polymer (IIP)based on dipyridyl amine-coated Fe

3O4nanoparticles (NPs)

was synthesized as a novel magnetic adsorbent for rapidextraction preconcentration and determination of traceamounts of gold ions [39] This was characterized by FTIRSEM elemental analysis (CHN) and TGADSC The opti-mum conditions including pH of sample eluant type andconcentration and also the least amount of eluant necessaryfor desorption of gold ions and the time of adsorptionwere obtained The effect of various cationic interferenceson the adsorption of gold specifically Pt(II) and Pd(II) ionswas evaluated The maximum capacity of the IIP modifiedmagnetic nanoparticles was found to be greater than 76mggFurthermore the accuracy of this method was confirmedusing various standard materials This method was alsoapplied successfully for preconcentration and determinationof gold ions in some real samples

Another precious metal is silver and has been selectivelybound from imprinted polymers Using blends of chitosanand polyvinyl alcohol as film-forming materials the metalion-imprinted membrane was prepared with silver ions astemplate [40]TheDSC curve shows that the membrane doesnot exhibit the heat resistance very well but the favorablecompatibility FTIR analysis implies that the coordinatingatoms may be N atom of amino group in chitosan andO atom of ndashOH in polyvinyl alcohol The results of theexperiment of competitive adsorption indicate that silver-MIP has the ability of specificity and recognition toAg(I)Thelarge adsorption capacity for Ag(I) indicates that silver-MIPcan be used in silver enrichment and separation from wastesolutions as an effective material

Another study reports the preparation of chitosan hydro-gels and imprinting by silver with different mass ratios [41]Compared with the native chitosan hydrogel sample theoptimally imprinted sample (Agim75) presents a significantlyenhancedAg I adsorption capacity aswell as a high selectivityThis is attributed to the specific cavities formed by thetemplate Ag(I) ions in the polymer matrix The effects ofthe adsorption conditions and desorption process were alsostudied

A more detailed study investigates the synthesis of ion-imprinted polymers (IIPs) for selective extraction of Ag(I)ions from aqueous solution by a precipitation polymerizationmethod using two functionalmonomers 4-vinyl pyridine (4-VP) and 1-vinyl imidazole (1-VID) andNN-ethylene bisacry-lamide (EBAm) as the cross-linker [42] Batch adsorptionexperiments were carried out as a function ofAg(I) imprintedpolymer amount agitation time pH and initial Ag(I) con-centrationThe kinetic studies indicated that pseudo-second-order kinetic model best describes the adsorption behaviorwhile the adsorption data correlated well with the Langmuirisotherm Furthermore the selectivity studies revealed thatthe ion-imprinted polymers had a higher absorption capacityand a higher selectivity for the Ag(I) ions than the controlpolymers

The selective binding of platinum was also studied usingMIPs in some recent works A new Pt-imprinted polymer

was synthesized by bulk polymerization by using platinum-iodide-vinyl pyridinium ion ternary ion association complexas a template with 2-hydroxy ethyl methacrylate (functionalmonomer) and ethylene glycol dimethacrylate (cross-linkingmonomer) in the presence of 221015840-azo-bis-isobutyronitrileas initiator [43] The synthesis was carried out thermallyat 60∘C in methanol medium and the resultant polymermaterial was dried and filtered to get unleached polymerparticles The imprinting anionic species were removedby stirring the above particles for 18 h with 6M HCI toobtain leached polymer particles These leached polymerparticles will now selectively rebind with [PtI

6]2minus species

NIPs were similarly prepared without the template Controlunleached and leached polymer particles were character-ized by XRD UV-Vis spectrophotometric and SEM studiesVarious parameters that influence the recovery of platinumfrom dilute aqueous solutions were systematically studiedand the results obtained are described in this paper In allthese studies the imprinting effect was noticed Furthermorethe percent recoveries obtained with leached and controlpolymer particles for platinum and other noble metals andbase metals which are likely to coexist with platinum inits minerals were also studied These studies indicate thepossibility of selective recovery of platinum from itsminerals

Another ion-imprinted polymer (IIP) was obtainedby copolymerization of methacrylic acid (as a functionalmonomer) and ethylene glycol dimethacrylate (as a cross-linking agent) in the presence of various chelating agentsfor Pt(II) ion and using 221015840-azo-bis-isobutyronitrile as theinitiator [44] Specifically acetaldehyde thiosemicarbazone(AcTSn) and benzaldehyde thiosemicarbazone (BnTSn) wereused as chelators The IIPs were applied as sorbents for solid-phase extraction of Pt(II) and Pt(IV) ions from aqueoussolutions The effects of acidity and flow rate of the sampleof elution conditions and of potentially interfering ionswere investigated The imprinting effect of analyte is clearlydemonstrated by the fact that only the IIP is capable ofquantitative retention of Pt(II) and Pt(IV) ions The methodworks best in the pH range from 05 to 1 and from 35 to 95The ions can be recovered with an acidic solution of thioureaThe Pt-AcTSn polymer displays better sorption propertiesfor the separation of analytes The selectivity coefficientsof the Pt-AcTSn and control polymers for Pt(IV) in thepresence of Pd(II) Rh(III) Ru(III) Al(III) and Cu(II) werecalculated and the sorbent capacity for Pt(IV) was foundto be 456mgg The method was successfully applied to thedetermination of Pt(IV) by electrothermal atomic absorptionspectrometry in tap water tunnel dust and anode slimesamples

In summary the rebinding capacity of Ag Au Pt - MIPsis ranged from a very small number of 120583gg to even 85mgg[36 41ndash44] The latter was related from the synthesis andpolymerization conditions

4 Future Aspects

The advantages that MIPs offer as selective sorbents havebeen demonstrated MIPs are easy to obtain and in some


studies it has been shown that their selectivity is extremelyhigh Moreover the applicability of MIPs in SPE proceduresdemonstrates the feasibility of using aMIP in several formatsfor extracting numerous templates from different samplesNowadays its applicability is not only for pharmaceuticalstargets but also for environmental pollutants So except forthe other target molecules (dyes ions phenols etc) thedeposit of some high-added value compounds as Au Agand Pt has been studied in order to make their binding viamolecular imprinting successful The capability of binding inhigh selectivity percentages is the key for MIPs to be usedsuccessfully inmany crucial environmental targets Althoughany can doubt about the economic feasibility of MIPs use therecovery and reuse in the case of precious metals make themvery attractive for future industrial applications

5 Conclusions

Molecular imprinting witnessed rapid development and canbe used as technique for high-added value compoundsGiven the value of some precious metals as gold silverand platinum MIPs have been already successfully tested asmaterials for their selective binding exporting impressivelyhigh selectivity results The capacity of these materials isnot large but MIPs use is focused on selectivity and notadsorption capacity It is a fact that the major advantageof MIPs is not their adsorptionbinding capacity but theirselectivity As it is widely known the criteria for the selectionof each material used are the combination and coevaluationof (i) cost (ii) reuse (iii) adsorption capacity and (iv)selectivity However in the present case where the targets arehigh-added value metals (Ag Au and Pt) a more complexselection should be done given the selective ability of MIPs torebind the targets Therefore the adsorption capacity is notthe principal criterion but the selectivity

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The support for this study was received from the StateScholarships Foundation (IKY) of Greek Ministry of Edu-cation and Religious Affairs (in the framework of the Hel-lenic Republic- Siemens Settlement Agreement) throughthe research program ldquoIKY Fellowships of Excellence forPostgraduate Studies in Greece-Siemens Programrdquo under thetitle ldquoAdvanced Molecularly Imprinted Polymers (MIPs) asMaterials for the Selective Binding and Recovery of VariousHigh-Added Value Environmental Targets with Applicationto Industrial-Scale Adsorption Columnsrdquo which is highlyappreciated

References

[1] B Chen S Piletsky and A P F Turner ldquoMolecular recognitiondesign of lsquokeysrsquordquo Combinatorial Chemistry and HighThroughputScreening vol 5 no 6 pp 409ndash427 2002

[2] R Srinivasan ldquoAdvances in application of natural clay and itscomposites in removal of biological organic and inorganiccontaminants from drinking waterrdquo Advances in MaterialsScience and Engineering vol 2011 Article ID 872531 17 pages2011

[3] H Sasaki Y Kobashi T Nagai and M Maeda ldquoApplication ofelectron beam melting to the removal of phosphorus from sil-icon toward production of solar-grade silicon by metallurgicalprocessesrdquo Advances in Materials Science and Engineering vol2013 Article ID 857196 8 pages 2013

[4] A Radenovic J Malina and T Sofilic ldquoCharacterization ofladle furnace slag from carbon steel production as a potentialadsorbentrdquo Advances in Materials Science and Engineering vol2013 Article ID 198240 6 pages 2013

[5] S M Alahmadi S Mohamad andM JamilMaah ldquoPreparationof organic-inorganic hybrid materials based on MCM-41 andits applicationsrdquo Advances in Materials Science and Engineeringvol 2013 Article ID 634863 8 pages 2013

[6] A G Balogh K Baba D D Cohen R G EllimanW Ensingerand J Gyulai ldquoModification synthesis and analysis of advancedmaterials using ion beam techniquesrdquo Advances in MaterialsScience and Engineering vol 2012 Article ID 431297 2 pages2012

[7] G Jiang T Chen and Q Yang ldquoPhotocatalytic materialsrdquoAdvances inMaterials Science and Engineering vol 2012 ArticleID 186948 2 pages 2012

[8] Y Mobarak M Bassyouni and M Almutawa ldquoMaterials selec-tion synthesis and dielectrical properties of PVCnanocompos-itesrdquo Advances in Materials Science and Engineering vol 2013Article ID 149672 6 pages 2013

[9] M V Polyakov ldquoAdsorption properties and structure of silicagelrdquoThe Journal of Physical Chemistry vol 2 pp 799ndash805 1931

[10] F H Dickey ldquoSpecific adsorptionrdquo The Journal of PhysicalChemistry vol 59 no 8 pp 695ndash707 1955

[11] G Wulff and A Sarhan ldquoUse of polymers with enzyme-analogous structures for the resolution of racematesrdquo Ange-wandte ChemiemdashInternational Edition in English vol 11 pp341ndash344 1972

[12] B Sellergren and L Andersson ldquoMolecular recognition inmacroporous polymers prepared by a substrate analogueimprinting strategyrdquo Journal of Organic Chemistry vol 55 no10 pp 3381ndash3383 1990

[13] K J Shea and D Y Sasaki ldquoAn analysis of small-moleculebinding to functionalized synthetic polymers by13C CPMASNMR and FT-IR spectroscopyrdquo Journal of the American Chem-ical Society vol 113 no 11 pp 4109ndash4120 1991

[14] G Wulff ldquoEnzyme-like catalysis by molecularly imprintedpolymersrdquo Chemical Reviews vol 102 no 1 pp 1ndash27 2002

[15] R Arshady and K Mosbach ldquoSynthesis of substrate-selectivepolymers by host-guest polymerizationrdquo MacromolecularChemistry vol 182 no 2 pp 687ndash692 1981

[16] M J Whitcombe M E Rodriguez P Villar and E NVulfson ldquoA new method for the introduction of recognitionsite functionality into polymers prepared bymolecular imprint-ing synthesis and characterization of polymeric receptors forcholesterolrdquo Journal of the American Chemical Society vol 117no 27 pp 7105ndash7111 1995


[17] B Sellergren ldquoImprinted dispersion polymers a new class ofeasily accessible affinity stationary phasesrdquo Journal of Chro-matography A vol 673 no 1 pp 133ndash141 1994

[18] S A Piletsky E V Piletska K Karim K W Freebairn CH Legge and A P F Turner ldquoPolymer cookery influence ofpolymerization conditions on the performance of molecularlyimprinted polymersrdquoMacromolecules vol 35 no 19 pp 7499ndash7504 2002

[19] D J OrsquoShannessy B Ekberg and K Mosbach ldquoMolecularimprinting of amino acid derivatives at low temperature (0∘C)using photolytic homolysis of azobisnitrilesrdquo Analytical Bio-chemistry vol 177 no 1 pp 144ndash149 1989

[20] D Spivak M A Gilmore and K J Shea ldquoEvaluation ofbinding and origins of specificity of 9-ethyladenine imprintedpolymersrdquo Journal of the American Chemical Society vol 119no 19 pp 4388ndash4393 1997

[21] G Wulff B Heide and G Helfmeier ldquoEnzyme-analogue builtpolymers 24 On the distance accuracy of functional groupsin polymers and silicas introduced by a template approachrdquoReactive Polymers Ion Exchangers Sorbents vol 6 no 2-3 pp299ndash310 1987

[22] M Sibrian-Vazquez and D A Spivak ldquoCharacterization ofmolecularly imprinted polymers employing crosslinkers withnonsymmetric polymerizable groupsrdquo Journal of Polymer Sci-ence A Polymer Chemistry vol 42 no 15 pp 3668ndash3675 2004

[23] B Sellergren ldquoDirect drug determination by selective sampleenrichment on an imprinted polymerrdquo Analytical Chemistryvol 66 no 9 pp 1578ndash1582 1994

[24] G Z Kyzas D N Bikiaris and N K Lazaridis ldquoSelectiveseparation of basic and reactive dyes by molecularly imprintedpolymers (MIPs)rdquoChemical Engineering Journal vol 149 no 1ndash3 pp 263ndash272 2009

[25] E Caro R M Marce P A G Cormack D C Sherringtonand F Borrull ldquoOn-line solid-phase extraction with molec-ularly imprinted polymers to selectively extract substituted4-chlorophenols and 4-nitrophenol from waterrdquo Journal ofChromatography A vol 995 no 1-2 pp 233ndash238 2003

[26] O Bruggemann A Visnjevski R Burch and P Patel ldquoSelectiveextraction of antioxidants with molecularly imprinted poly-mersrdquo Analytica Chimica Acta vol 504 no 1 pp 81ndash88 2004

[27] K Tsukaghoshi K Y Yu M Maeda and M Takagi ldquoMetalion- selective adsorbent prepared by surface-imprinting poly-merizationrdquo Bulletin of the Chemical Society of Japan vol 66pp 114ndash120 1993

[28] Y Koide H Shosenji M Maeda and M Takagi ldquoSelectiveadsorption of metal ions to surface-templated resins preparedby emulsion polymerization using a functional surfactantrdquoACSSymposium Series vol 703 pp 264ndash277 1998

[29] H Chen M M Olmstead R L Albright J Devenyi and RH Fish ldquoMetal-ion-templated polymers Synthesis and struc-ture of N-(4-vinylbenzyl)-147-triazacyclononanezinc(II) com-plexes their copolymerization with divinylbenzene and metal-ion selectivity studies of the demetalated resinsmdashevidencefor a sandwich complex in the polymer matrixrdquo AngewandteChemiemdashInternational Edition in English vol 36 no 6 pp 642ndash645 1997

[30] J M Gladis and T P Rao ldquoEffect of porogen type on thesynthesis of uranium ion imprinted polymer materials for thepreconcentrationseparation of traces of uraniumrdquoMicrochim-ica Acta vol 146 no 3-4 pp 251ndash258 2004

[31] R Kala J Mary Gladis and T Prasada Rao ldquoPreconcentrativeseparation of erbium from Y Dy Ho Tb and Tm by using

ion imprinted polymer particles via solid phase extractionrdquoAnalytica Chimica Acta vol 518 no 1-2 pp 143ndash150 2004

[32] V M Biju J M Gladis and T P Rao ldquoIon imprinted poly-mer particles synthesis characterization and dysprosium ionuptake properties suitable for analytical applicationsrdquoAnalyticaChimica Acta vol 478 no 1 pp 43ndash51 2003

[33] O Vigneau C Pinel and M Lemaire ldquoSeparation of lan-thanides by ion chromatography with imprinted polymersrdquoChemistry Letters vol 32 no 6 pp 530ndash531 2003

[34] Y Liu X Chang S Wang Y Guo B Din and S MengldquoSolid-phase extraction and preconcentration of cadmium(II)in aqueous solution with Cd(II)-imprinted resin (poly-Cd(II)-DAAB-VP) packed columnsrdquo Analytica Chimica Acta vol 519no 2 pp 173ndash179 2004

[35] O Guney Y Yilmaz and O Pekcan ldquoMetal ion templatedchemosensor for metal ions based on fluorescence quenchingrdquoSensors and Actuators B Chemical vol 85 no 1-2 pp 86ndash892002

[36] M E H Ahamed X Y Mbianda A F Mulaba-Bafubiandiand L Marjanovic ldquoSelective extraction of gold(III) frommetal chloride mixtures using ethylenediamine N-(2-(1-imidazolyl)ethyl) chitosan ion-imprinted polymerrdquoHydrometallurgy vol 140 pp 1ndash13 2013

[37] E Moazzen H Ebrahimzadeh M M Amini and O SadeghildquoA high selective ion-imprinted polymer grafted on a novelnanoporous material for efficient gold extractionrdquo Journal ofSeparation Science vol 36 no 11 pp 1826ndash1833 2013

[38] H Ebrahimzadeh E Moazzen M M Amini and O SadeghildquoNovel ion-imprinted polymer coated on nanoporous silicaas a highly selective sorbent for the extraction of ultratracequantities of gold ions frommine stone samplesrdquoMicrochimicaActa vol 180 no 5-6 pp 445ndash451 2013

[39] H Ebrahimzadeh E Moazzen M M Amini and O SadeghildquoNovel magnetic ion imprinted polymer as a highly selectivesorbent for extraction of gold ions in aqueous samplesrdquo Ana-lytical Methods vol 4 no 10 pp 3232ndash3237 2012

[40] X Wang L Zhang C Ma R Song H Hou and D LildquoEnrichment and separation of silver from waste solutions bymetal ion imprinted membranerdquoHydrometallurgy vol 100 no1-2 pp 82ndash86 2009

[41] X Song C Li R Xu and K Wang ldquoMolecular-ion-imprintedchitosan hydrogels for the selective adsorption of silver(I)in aqueous solutionrdquo Industrial and Engineering ChemistryResearch vol 51 no 34 pp 11261ndash11265 2012

[42] M Ahamed X Y Mbianda A F Mulaba-Bafubiandi and LMarjanovic ldquoIon imprinted polymers for the selective extrac-tion of silver(I) ions in aqueous media kinetic modeling andisotherm studiesrdquo Reactive and Functional Polymers vol 73 no3 pp 474ndash483 2013

[43] S Daniel and T Prasada Rao ldquoIon imprinted polymersmdasha newstrategy based on the utilization of ion association complex ofplatinum as a templaterdquo in Proceedings of the 29th IPMI AnnualPrecious Metals Conference pp 78ndash90 2005

[44] B Lesniewska M Kosinska B Godlewska-Zyłkiewicz EZambrzycka and A Z Wilczewska ldquoSelective solid phaseextraction of platinum on an ion imprinted polymers for itselectrothermal atomic absorption spectrometric determinationin environmental samplesrdquoMicrochimica Acta vol 175 no 3-4pp 273ndash282 2011

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


reported that they had prepared an organic MIP using non-covalent interactions only [15]This approach was termed theldquononcovalent approachrdquo as opposed to the covalent approachfavoured by Wulff and it was this approach with its simpleseemingly trivial methodology that triggered the explosionin molecular imprinting that occurred during the 1990sNoncovalent imprinting uses the typical forces of attractionbetweenmolecules such as hydrogen bonds ion pairs dipole-dipole interactions and van der Waals forces to generateadducts of template and functional monomers in solutionUnlike those used in covalent methods of imprinting theseadducts are unstable and dynamically rearrange on a timescale relevant to the imprinting process To this day thenoncovalent versus covalent debate continues with bothsides being championed However it is generally acceptedthat there are pros and cons to both approaches So in1995 Whitcombe et al reported an intermediate approachthat combines the advantages of both approaches [16] Thisapproach relies on covalent interaction during the polymer-ization stage but noncovalent interactions during rebindingImportantly in order to improve subsequent noncovalentbinding geometry Whitcombersquos approach incorporated asacrificial spacer group that was designed to be lost duringtemplate removal The noncovalent approach however is stillby far the most widely used approach in MIP synthesisSeveral of its drawbacks can be overcome by the use ofstoichiometrically associating monomer-template systems[17] This has resulted in a range of receptors exhibitinghigh capacity and effective recognition properties in aqueousmedia

The simplicity of use the relatively low cost and the broadrange of possible guest molecules (small organic moleculesions and also biological macromolecules) have since led tothe important development of this technique as illustratedby the increasing numbers of publications over recent years(Figure 1)

It is a great of interest to preparedesign materialswhich only selectively remove carcinogenic pollutants fromwastewaters as ions phenols and drugspharmaceuticalsNowadays MIPs are highly cross-linked polymeric phaseswith predetermined selectivity for a single molecule or agroup of structurally related molecules (template) employedin separation processes of environmental pollutants (chro-matography solid-phase extraction membrane separationsand adsorption) artificial antibodies and sensors recogni-tion elements [14]

This review aims to gather and report (i) recent synthesisroutes of MIPs and (ii) their environmental applications forldquohot pollutantsrdquo of high-added value metals discharged inenvironmental ways The novelty of this work is clear giventhe lack of review articles or overviews regarding the use ofMIPs for high-added valuemetals Scopus which is one of thelargest abstract and citation database of peer-reviewed worksgives 136 results after searching with terms as ldquoMolecularlyImprintedrdquo However none of them are special for metals (orprecious metals)

0

200

400

600

800

1000

1200

1400

1600

Pape

rs

2011

ndash2013

2001

ndash2010

1991

ndash2000

1981

ndash1990

1971

ndash1980

1961

ndash1970

1951

ndash1960

1900

ndash1950

Figure 1 Works published for ldquomolecular imprinted polymersrdquoterm (data after search in Scopus)

2 Design and Synthesis of MIPs

The preparation of MIPs starts by positioning the functionalmonomers around a template molecule The monomersinteract with sites on the template via interactions that canbe reversibly covalent or noncovalent (hydrogen ionic vander Waals 120587-120587 etc) Then they are polymerized and cross-linked around the template in order to fix their position andto ldquofreezerdquo the geometry of the pores in the network Thetemplate molecule is then extracted leaving a polymer withfunctional sites capable of molecular recognition

The first step is the contact between the functionalisedmonomers and the template molecule which leads to theformation of a complex Its structure and stability will thendetermine the behaviour of the future MIP The interactionsinvolved must be sufficiently strong to remain intact duringthe polymerisation stage but sufficiently labile to enabletemplate extraction and reinsertion of guest molecules in thelater stages These interactions must therefore occur rapidlyand be reversible It is crucial to optimise the choice of thedifferent components of the system at this point

Different types of strategies can be distinguished depend-ing on whether the bonding between template and host iscovalent or not (i) covalent interactions (ii) noncovalentinteractions and (iii) double approach covalent plus nonco-valent

The second step is the polymerisation step of themonomers around the complex formed in the first step [18]Owing to its ease of use radical polymerisation is the mostfrequent The crucial question is to determine how to carryout this polymerisationcross-linking step with minimumdisturbance of the complex already in place Choices mustbe made for instance in radical polymerization the radicalscan be generated at 60∘C (aa1015840-azobutyronitrile as initiatordenoted as AIBN) 45∘C (azobis valeronitrile as initiatordenoted as ABDV) which could cause heat destabilisation ofthe complex or at 4∘C with low-temperature photochemical















N N

Cl

NO

N N

Cl

N

O


MAA(monomer)

EGD

MA

(cross-linker)

C2H5CH2

CH2CH2

CH3

CH3

N+

O2NO2N

H2C

C2H5

N+

CH3

CH3

CH3

Clminus Ominus

H3CCH2CH2

CH3

CH3

N N

Cl

N

O

C2H5

N+

O2N

Ominus

H3CCH2CH2

CH3

CH3

HmdashO


pH 10

OOminus

(a)

O

O

AA

m

NN

OH

S S

HN

N NCl

N NH

SO

OO S

O

OONa

ONa

O

O O

O ONa

SO

OSO

ONaO

NaO

NN

OH

S S

HN

N NCl

N NH

SO

OO S

O

OO

O

OO

O

O O

SO

OOS

O

OO

OO

O

O

O


MBA

minusTe

mpl

ate

+Te

mpl

ate

pH2

(template)

(monom

er)

CH2

CH2

H2N

NH3

H3C

C

OC

OC

OC

H2C


H3N

NH3

NH3

H2CH2C

NH3

OC

NH3

H3N

H3N

H3N

OC

NH3

O

OO

OS

CH3N

N N

NCl

N

NHN

OC NH3

OC

H3N

OCH3N

O3S

SO3 SO3

SO3

O3S

OHHN

(b)




2S2O8initiator




2

















6]2minus species




4 Future Aspects




5 Conclusions




Acknowledgments


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials

















N N

Cl

NO

N N

Cl

N

O


MAA(monomer)

EGD

MA

(cross-linker)

C2H5CH2

CH2CH2

CH3

CH3

N+

O2NO2N

H2C

C2H5

N+

CH3

CH3

CH3

Clminus Ominus

H3CCH2CH2

CH3

CH3

N N

Cl

N

O

C2H5

N+

O2N

Ominus

H3CCH2CH2

CH3

CH3

HmdashO


pH 10

OOminus

(a)

O

O

AA

m

NN

OH

S S

HN

N NCl

N NH

SO

OO S

O

OONa

ONa

O

O O

O ONa

SO

OSO

ONaO

NaO

NN

OH

S S

HN

N NCl

N NH

SO

OO S

O

OO

O

OO

O

O O

SO

OOS

O

OO

OO

O

O

O


MBA

minusTe

mpl

ate

+Te

mpl

ate

pH2

(template)

(monom

er)

CH2

CH2

H2N

NH3

H3C

C

OC

OC

OC

H2C


H3N

NH3

NH3

H2CH2C

NH3

OC

NH3

H3N

H3N

H3N

OC

NH3

O

OO

OS

CH3N

N N

NCl

N

NHN

OC NH3

OC

H3N

OCH3N

O3S

SO3 SO3

SO3

O3S

OHHN

(b)




2S2O8initiator




2

















6]2minus species




4 Future Aspects




5 Conclusions




Acknowledgments


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




N N

Cl

NO

N N

Cl

N

O


MAA(monomer)

EGD

MA

(cross-linker)

C2H5CH2

CH2CH2

CH3

CH3

N+

O2NO2N

H2C

C2H5

N+

CH3

CH3

CH3

Clminus Ominus

H3CCH2CH2

CH3

CH3

N N

Cl

N

O

C2H5

N+

O2N

Ominus

H3CCH2CH2

CH3

CH3

HmdashO


pH 10

OOminus

(a)

O

O

AA

m

NN

OH

S S

HN

N NCl

N NH

SO

OO S

O

OONa

ONa

O

O O

O ONa

SO

OSO

ONaO

NaO

NN

OH

S S

HN

N NCl

N NH

SO

OO S

O

OO

O

OO

O

O O

SO

OOS

O

OO

OO

O

O

O


MBA

minusTe

mpl

ate

+Te

mpl

ate

pH2

(template)

(monom

er)

CH2

CH2

H2N

NH3

H3C

C

OC

OC

OC

H2C


H3N

NH3

NH3

H2CH2C

NH3

OC

NH3

H3N

H3N

H3N

OC

NH3

O

OO

OS

CH3N

N N

NCl

N

NHN

OC NH3

OC

H3N

OCH3N

O3S

SO3 SO3

SO3

O3S

OHHN

(b)




2S2O8initiator




2

















6]2minus species




4 Future Aspects




5 Conclusions




Acknowledgments


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





2S2O8initiator




2

















6]2minus species




4 Future Aspects




5 Conclusions




Acknowledgments


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials













6]2minus species




4 Future Aspects




5 Conclusions




Acknowledgments


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





5 Conclusions




Acknowledgments


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials








































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Documents

Review Article Molecular Imprinting for High-Added Value ...downloads.hindawi.com/journals/amse/2014/932637.pdf · F : Works published for molecular imprinted polymers term (data