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Novel Method of Incorporating Silver Nanoparticles intoNatural Rubber Latex FoamIndrajith Rathnayake a , Hanafi Ismail a , Baharin Azahari b , Chaturanga Bandara c & SanathRajapakse ca School of Materials and Mineral Resources Engineering, University Sains Malaysia , Penang ,Malaysiab School of Industrial Technology, University Sains Malaysia , Penang , Malaysiac Department of Molecular Biology & Biotechnology , Faculty of Science, University ofPeradeniya , Sri LankaAccepted author version posted online: 28 Feb 2013.Published online: 02 Jul 2013.

To cite this article: Indrajith Rathnayake , Hanafi Ismail , Baharin Azahari , Chaturanga Bandara & Sanath Rajapakse (2013)Novel Method of Incorporating Silver Nanoparticles into Natural Rubber Latex Foam, Polymer-Plastics Technology andEngineering, 52:9, 885-891, DOI: 10.1080/03602559.2013.763366

To link to this article: http://dx.doi.org/10.1080/03602559.2013.763366

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Novel Method of Incorporating Silver Nanoparticlesinto Natural Rubber Latex Foam

Indrajith Rathnayake1, Hanafi Ismail1, Baharin Azahari2, Chaturanga Bandara3,and Sanath Rajapakse31School of Materials and Mineral Resources Engineering, University Sains Malaysia, Penang,Malaysia2School of Industrial Technology, University Sains Malaysia, Penang, Malaysia3Department of Molecular Biology & Biotechnology, Faculty of Science, University of Peradeniya,Sri Lanka

Silver nanoparticles (SNP) incorporated potassium oleate(KOL) soap by in situ reduction of silver nitrate by trisodium citrate(TSC) was described. Novel incorporation method of SNP into thenatural rubber latex foam (NRLF) was successfully carried out bymixing 4 parts per hundred rubber (pphr) of SNP incorporatedKOL soap in to the natural rubber latex (NRL) compound.UV-Visible spectrophotometer analysis, particle size analysis dataand transmission electron micrograph analysis proved the modifiedKOL soap consisted of stable mono-dispersed nanometer size silverparticles. SEM/EDX analysis of a latex film made out with modifiedNRL compound by SNP incorporated KOL soap shows nanosizedsilver particles inside it. Modified KOL and final product of modi-fied NRLF by SNP incorporated KOL soap tested for antimicrobialproperties against Escherichia coli (E. coli). The resultant KOLitself can inhibit Gram negative E. coli bacterium in a very strongmanner. Inhibition of the same strain of E. coli bacterium bymodified NRLF showed positive result.

Keywords Antibacterial activities; Nanotechnology; Naturalrubber latex foam; Potassium Oleate soap; SilverNanoparticles

INTRODUCTION

Potassium or sodium divertive of long chain carboxylatesoap such as oleate, ricinoletes, castor-oil soaps are widelyuse as foaming agents in the process of making NRLF bythe Dunlop method[1]. Potassium oleate (KOL) soap is themost common type foaming agent in Dunlop manufacturingmethod of makingNRLF[2,3]. KOL is synthesized by neutra-lizing of oleic acid by potassium hydroxide[4,5]. The typicalreaction of making KOL can be represented as follows:

C18H34O2 þ KOH�!C18H33O2K þ H2O ð1Þ

In nanotechnology, potassium or sodium oleate hasbeen used as capping agent in nanomaterials synthesis bymany researchers[6–8]. D. Ma et al.[9] reported that potass-ium oleate play very important role in the synthesis of sil-ver sulfide nanorods and nanotubes. They further reportedKOL works as soft template to control the morphology ofintermediate AgSCN and KOL acts as a linking material toconstruct silver sulphide nanorods and nanotube. X.-M. Niet al.[10] reported the use of potassium oleate as an anionicsurfactant for synthesizing nickel nanorods.

They have found that the formed thread-like micellesin water by potassium oleate has greater effect of the con-trolling of the size of the nickel nanorods and they alsosuggested the same water-in-oil microemulsion system tosynthesis another transition metal nanocrystals. Potassiumoleate also can be used as a capping agent for nanomater-ials synthesis, Q. Han et al.[8] reported the small amountof potassium oleate as a capping agent can make hier-archical tin sulphide architectures, they suggested thatthe capping ligand effect of oleate is responsible for mak-ing rod-like SnS architectures. Q. Li et al.[11] havereported potassium oleate together with ethylene glycol(EG) led the formation of Bismeth sulphide (Bi2S3)nano-fibers having 10 nm size diameter and lengthsranging from 400 nm to 1000 nm.

Application of silver nanoparticles on various productsand functions are well known in modern nanotechnology.Silver nanoparticles are mostly used as:

i. Applications in biology and medicine[12],ii. As an antimicrobial agent[13–15],iii. Applications electronic materials and sensors[16,17],iv. Applications as catalytic material[18]

Chemical reduction method is a well-established methodto produce SNP with reproducible results and smallerparticles sizes[19]. Many researchers used chemical reductionmethod to produce more stable silver nanocolloids to use in

Address correspondence to Hanafi Ismail, (Professor, PolymerDivision) School of Materials and Mineral Resources Engineer-ing, University Sains Malaysia, USM Eng. Campus, 14300,Nibong Tebal, Penang, Malaysia. E-mail: hanafi@eng.usm.my

Polymer-Plastics Technology and Engineering, 52: 885–891, 2013

Copyright # Taylor & Francis Group, LLC

ISSN: 0360-2559 print=1525-6111 online

DOI: 10.1080/03602559.2013.763366

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many applications[20–24]. Reducing of AgNO3 by TSC isvery easy and a reliable method of producing SNP in anaqueous medium; moreover, the stability of the nano-silvercolloid production by this method is very much appreci-ated[25–28].

In our previous studies, incorporations of silver nano-particles into the NRLF matrix were done using two differ-ent manners, one is in-situ deposition of silver nanopartclesin to the previously prepared NRLF matrix[29] and theother method was mixing of silver nanocolloid to theNRL compound mixer[30]. This novel method will be amore suitable and practical method to make silver nano-particles incorporated natural rubber latex foam not onlyin lab-scale synthesis but also in large-scale production.

In the present study, synthesis and characterization ofsilver nanoparticles incorporated potassium oleat soap isexplained. Incorporation of silver nanoparticles to KOLwas done by in situ reduction of silver nitrate by TSC inthe presence of oleic acid, potassium hydroxide andde-ionized water. Stable silver nanoparticles in potassiumoleate soap can use as a more convenient carrier materialof SNP to natural rubber latex foam materials in the syn-thesis of silver nanopartciles incorporated natural rubberlatex foam. Potassium oleate soap acts as a foaming agentand as well as a compatible transporter of silver nanopart-ciles to the natural rubber latex foam matrix to make theantibacterial NRLF.

MATERIALS AND METHOD

Chemicals for synthesis of silver nanoparticles incorpor-ated potassium oleate soap were purchased from MerckKGaA, Germany and Sigma Aldrich Chemicals, USA.Chemicals for making natural rubber latex foam materialsuch as natural rubber latex (Low Ammonia (LATZ) type),sulphur (S), phenolic type antioxidant (Naftocit ZMP),zinc 2-mercaptobenzhiozolate (ZMBT) and zinc diethyl-dithiocarbamate (ZDEC), zinc oxide (ZnO), diphenylgua-nidine (DPG), and sodium silicofluoride (SSF) weresupplied by Zarm Scientific & Supplies (M) Sdn Bhd,Malaysia. Chemicals for antimicrobial susceptibility testswere obtained from Sigma Aldrich Chemicals, USA. E. coli(strain number: NCTC 10418) was obtained from Facultyof Dental, University of Peradeniya, Sri Lanka.

Synthesis of Nano-Silver-based NRLF

Synthesis of Silver Nanoparticle Incorporated PotassiumOleate Soap

A potassium oleate soap (20%) having silver nanopar-ticle was prepared as follows. Mixer A: 100ml of oleicacid was mixed with 402ml of de-ionized water in atri-necked flask in a water bath, and then 4ml of 0.1Msilver nitrate was added to the solution. The mixer was

kept on a hot plate while mixing vigorously by meansof a mechanical stir.

Mixer B consisted of 23.3 g of potassium hydroxide and43ml of de-ionized water. Mixer B was added dropwise toMixer A, when the temperature of Mixer A increased up to80�C. The whole emulsion was stirred vigorously by meansof a mechanical agitator. The reaction was carried out for10min and 100ml of 36mmol tri-sodium citrate was addeddropwise into the mixer while mixing vigorously. Next, thetemperature of the reaction mixer was reduced to ambienttemperature and kept stirring at low speed for 24 h.

Compounding and Production of Nano-Silver-based NRLF

The formulation used to make the silver nanocolloid-incorporated NRLF is shown in Table 1. First LATZ typeNRL was mixed with sulphur, antioxidant, previously pre-pared silver nanocolloids as shown in Figure 1 and potass-ium oleate soap, while stirring at 10 rpm. After 2 h, zinc2-mercaptobenzhiozolate (ZMBT) and zinc diethyldithio-carbamate (ZDEC) were slowly added to the mixture. Thenthe compounded NRLF compound was matured for 8 h atroom temperature with stirring at 10 rpm.

After maturation, the NRLF compound was vigorouslybeaten using a stand mixer (KENWOOD, kMix) to make afine foam until the volume was increased up to three timesfrom the initial volume (beating time about 5min). Afterthat 3.00 pphr of ZnO together with 0.30 pphr of diphenyl-guanidine (DPG) were added as the primary gelling agent

TABLE 1Formulation for latex compound for synthesis of silvernanoparticles incorporated natural rubber latex foam

samples

Ingredients

Dry parts perhundred rubber (pphr)

ControlSample

SNP-KOLincorporated

NRLF

60% LATZ type NR Latex 100.00 100.0020% Silver nanoparticleincorporated potassiumoleate soap

0.00 3.00

20% Pure potassium oleate soap 3.00 0.0050% Sulphur 2.50 2.5050% Phenolic type antioxidant(Vulkanox SKF)

1.00 1.00

50% ZMBT 1.00 1.0050% ZDEC 1.00 1.0040% ZnO 3.00 3.0040% DPG 0.30 0.3025% SSF 1.00 1.00

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to the foam and beating was continued for another 90 s.Then secondary gelling agent, 1.00 pphr of sodium silico-fluoride (SSF) was quickly added and the foam was beatenfor another 90 s. Finally the un-gelled foamwas immediatelypoured into the aluminum mould and allowed to gel for2min at ambient temperature. Gelled foam was then curedin a hot air oven at 100�C for 2 h. Then the cured foam wasstripped out from the mould and thoroughly washed withde-ionized water to remove soap and non-reacted elements.After washing, the cured NRLF was dried in a hot air ovenat 80�C for 8 h. The resultant foam was off-white in color.The same procedure was used without silver nanocolloidsto produce the control sample of NRLF.

CHARACTERIZATION

The following procedure was followed:

1. The silver nanocolloidal sample was tested using VAR-IAN Cary 50 conc UV=Vis Spectrophotometer. Liquidsamples of silver nanocolloid synthesized in de-ionizedwater by reduction of silver nitrate by tri-sodium citrateas explained in our previous research work[29] was testedfor UV-Visible analysis. Also the control potassiumoleate and modified potassium oleate were tested forUV-Visible analysis.

2. The particle size analysis of the nano-sized silver wasdone using NANOPHOX (NX0064) particle size analy-zer. Diluted liquid sample of modified potassium oleatesoap tested with particle size analyzer to investigate sizesand size distribution of nano silver particles in soapemulsion.

3. The Transmission Electron Microscope (TEM) used toget the TEM images was a Philips Model CM12. Asmall drop of diluted sample of modified KOL wasput on the copper grid very carefully and allowed todry for 1 h. Then the copper grid was placed carefullyinside the instrument and tested to get TEM images.The resultant TEM images were analyzed using Docuversion 3.2 image analysis.

4. SEM and elemental analysis were done using a ZEISS,Supra TM 35VP (Germany) scanning electron microscopeoperated at 10.00 kV coupled 180 with EDAX Genesiswas used to analysis SEM images and EDX analysis.Foam rubber samples were coated in Bio-RAD PolaronDivision, SEM coating system with alloy consisting of80% gold and 20% palladium.

5. Qualitative determination of antimicrobial testing wasdone as described in following method. Luria broth(LB) medium was prepared and a single colony of Grampositive Staphylococcus aureus was inoculated in asepticconditions. SA-inoculated LB medium was then incu-bated at 37�C for 12 h in a mechanical shaker. Afterthe incubation period, 100 mL of 1� 108 CFU=ml bac-teria suspension was then added and evenly spread onthe Muller Hinton agar plates. The modified and unmo-dified foam pieces of size 10mm� 10mm were placed onthe agar plates and were aerobically incubated at 37�Cfor 24 h in an incubator. Antibacterial activity of themodified foam materials were assessed by examiningclear inhibition zone around the foam rubber samplesplaced on agar plates[31,32]. The same procedure was car-ried out for the Gram negative E. coli bacteria as well[33].

RESULTS AND DISCUSSION

Figure 1 shows the physical appearance of modified andcontrol KOL (without silver nanoparticles).The modifiedKOL by SNP is brown in color whereas the control KLOdoes not show any color as it is a clear gel. Colors andthe value of maximum absorption in UV-Vis of SNP col-loids vary depending on the size of silver nanoparticles inthe colloidal solution[34]. The brown color obtained forpure silver nanocolloid, which has the particle size of22 nm perfectly matched with the color of modified KOLby SNP. Figure 2 shows the UV-Vis graphs of each sample.

UV-VISIBLE ANALYSIS OF SNP-INCORPORATED KOL

Metal nanoparticles such as silver display a very intensepeak in UV-visible spectroscopic analysis due to SurfacePlasmon Resonance (SPR)[35–37]. The conduction bandand the valance band of metal nanoparticles lie very closeto each other in which electrons can be moved very easily.These free electrons give rise to a SPR absorption band inUV-Vis spectroscopy analysis[38,39]. Figure 2 shows theUV-Vis absorption peak of pure silver nanocolloids,modified KOL by SNP and pure KOL. The single

FIG. 1. (a) Physical appearance of a: silver nanoparticles synthesized in

de-ionized water, (b) Silver nanoparticles incorporated potassium oleate

soap after 6 months from initial synthesis, (c) Control potassium oleate

soap. (Color figure available online.)

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absorption peak at 429.1 nm is a characteristic peak ofnanoparticles of silver[40]. As shown in Figure 2 themaximum absorption peak for pure SNP was matched withthe maximum absorption peak of modified KOL. The con-trol KOL (i.e., without SNP) did not show any peak inUV-Vis absorption spectroscopic analysis.

SEM-EDX ANALYSIS OF NATURAL RUBBERLATEX FILM

Latex film was prepared using the same compound thatwas used to prepare the modified NRLF was evaluatedusing SEM-EDX analysis. The resultant SEM micrographshows nanometer-sizes particles embedded in the latex film,the EDX analysis of some selected nanometer size particlesproved that those particles are silver nanoparticles. Figure 3shows the SEMmicrograph together with EDX results. It is

clearly shows that scanned area (marked in yellowþ sign)was consisted with elemental silver in 3% of weight % and00.35% of atoms. The major element presented in the latexfilm was C (94.46 weight %, 99.16 atom %). The reason forthat is the main polymer part is cis-1, 4-polyisoprene(-C5-

H7-) units that mainly consist of C elements. ElementalZn was present in the EDX analysis due to the use ofZnO, ZDEC and ZMBT in the synthesis process of NRLF.However, other elements such as S and Si (from SSF), havenot been detected in this analysis.

Particle Size Analyzing Data

The particle sizes analyzed by a NANOPHOX (NX0064)particle size analyzer use the photon cross-correlationspectroscopy (PCCS) technique to measure the sizes of thenanosized particles. PCCS calculate the intensity variationof scattered light reflected from nanoparticles in liquidmedium[41]. The sizes given by the instruments were inbetween 34 nm to 50 nm, and the most of the particles were

FIG. 3. SEM micrograph and EDX analysis of modified natural rubber latex film; a: magnification at 10 X, b: magnification at 30X. (Color figure

available online.)

FIG. 2. Absorption vs. wavelength of (a) silver nanocolloid synthesized

in de-ionized water, (b) silver nanoparticles incorporated potassium oleate

soap (6 months affter initial synthesis), (c) pure potassium oleate soap.

(Color figure available online.)

FIG. 4. Particle size analyzing data of SNP modified potassium oleate

soap. (Color figure available online.)

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in 38 nm size. Figure 4 shows the cumulative distributionand the density distribution graphs given by the instruments.Also the cumulative distribution curve gave a narrow peak,and it was proved that the silver nanoparticles inside theKOL suspension have small size variation (mono disperse).

TEM Analyzing of AgNP

The TEM images taken for the modified KOL by SNPin Figure 6 clearly showed that the evenly distributedsilver nanoparticles in KOL mixer were below 19 nm.The shapes of the particles can be clearly identified as

spherical shapes in the high magnification image inFigure 5(b). The TEM image 5 (a) showed evenly distrib-uted SNP in the reaction media even after 6 months. Itproved that the silver nanoparticles formed in the KOLmixer were very stable in soap medium. The sizes givenby NANOPHOX (NX0064) are not matched exactly withthe sizes given by TEM analysis. The reason could be thehigh viscosity of the KOL emulsion did not give accuratesizes by this PCCS technique.

FIG. 5. TEMmicrograph of the SNP incorporated potassium oleate soap taken after 6 months from the initial synthesis, (a) magnification at 45K, and

(b) magnification at 100K. (Color figure available online.)

FIG. 6. Antibacterial activities of SNP-KOL vs pure KOL against E.

coli bacterium. (Color figure available online.)

FIG. 7. Antibacterial activities of SNP-KOL incorporated NRLF vs

pure control NRLF against E. coli bacterium. (Color figure available

online.)

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Results of the Antimicrobial Test

Figure 6 shows the antimicrobial activity of modifiedKOLsamples and control sample of KOL against Gram-negativeE. coli. It is clear that control sample (without silver nanopar-ticles) had no antibacterial activities against E. coli, whereasthe highest activity (i.e., a large diameter of the inhibitionzone) was shown in the modified sample. It was proven thatthe silver nanopartciles were the responsible elements forthe antibacterial activity of modified KOL.

Figure 7 shows the antibacterial activities of modifiedNRLF by silver nanoparticle incorporated KOL(SNP-KOL) against E. coli bacterium. The modifiedNRLF by SNP-KOL gives a clear inhibition zone, whereasthe control NRLF did not show any inhibition zoneagainst E. coli bacterium.

CONCLUSION

Reduction of silver nitrate using tri-sodium citrate in pot-assium oleate soap gave silver nanoparticle-incorporatedpotassium oleate soap, which had a greenish brown color.The sizes of silver nanoparticles present in the modifiedKOL were under 19 nm. Also it was found that the stabilityof the nanoparticles were excellent in the presence of KOL.KOL acts as an anionic stabilizing agent that can preventagglomeration of silver nanoparticles. Furthermore, theresultant KOL can inhibit Gram negative E.coli bacteriumin very strong manner. And, the SNP-KOL soap can actas a foaming agent as well as a convenient carrier mediafor making silver nanoparticle-incorporated NRL. Inhi-bition of Gram-negative E.coli bacterium by the resultantNRLF proved that the synthesis of antibacterial NRLFcan be carried out successfully by this novel method.

ACKNOWLEDGMENT

The Research University Grant (RU), Universiti SainsMalaysia is gratefully acknowledged for the financial sup-port (Grant number 1001=PBAHAN=814129).

REFERENCES

1. Blackley, D. C. Polymer Lattices: Science and Technology, Chapman

& Hall: New York, 1966, pp. 273–280.

2. Madge, E.W. Latex Foam Rubber. Maclaren and Sons, Ltd.: London,

1962.

3. Calvert, K.O. Polymer Lattices & Their Applications. Applied Science

Publishers: London, 1982.

4. Ali, M.F.; Bassam, M.; Speight, J.G. Handbook of Industrial

Chemistry. McGraw-Hill Professional: New York, 2005.

5. Salager, J. Surfactants Types and Uses.Version 2. FRIP Booklet#E300-A: Teaching Aid in Surfactant Science & Engineering in English.

Universidad De Los Andes, Merida-Venezuela, 2002.

6. Bao, L.; Low, W.L.; Jiang, J.; Ying, J.Y. Colloidal synthesis of

magnetic nanorods with tunable aspect ratios. J. Mater. Chem.

2012, 22, 7117–7120.

7. Croce, V.; Cosgrove, T.; Dreiss, C.A.; Maitland, G.; Hughes, T.;

Karlsson, G. Impacting the length of wormlike micelles using mixed

surfactant systems. Langmuir 2004, 20, 7984–7990.

8. Han, Q.; Wang, M.; Zhu, J.; Wu, X.; Lu, L.; Wang, X. Great influence

of a small amount of capping agents on the morphology of SnS

particles using xanthate as precursor. J. Alloys Compd. 2011, 509,

2180–2185.

9. Ma, D.; Hu, X.; Zhou, H.; Zhang, J.; Qian, Y. Shape-controlled

synthesis and formation mechanism of nanoparticles-assembled

Ag2S nanorods and nanotubes. J. Cryst. Growth 2007, 304, 163–168.

10. Ni, X.-M.; Su, X.-B.; Yang, Z.-P.; Zheng, H.-G. The preparation of

nickel nanorods in water-in-oil microemulsion. J. Cryst. Growth

2003, 252, 612–617.

11. Li, Q.; Shao, M.; Wu, J.; Yu, G.; Qian, Y. Synthesis of nano-fibrillar

bismuth sulfide by a surfactant-assisted approach. Inorgan. Chem.

Commun. 2002, 5, 933–936.

12. Salata, O. Applications of nanoparticles in biology and medicine.

J. Nanobiotechnol. 2004, 2, 1–6.

13. Sondi, I.; Salopek-Sondi, B. Silver nanoparticles as antimicrobial

agent: a case study on E: coli as a model for Gram-negative bacteria.

J. Coll. Interf. Sci. 2004, 275, 177–182.

14. Morones, J.R.; Elechiguerra, J.L.; Camacho, A.; Holt, K.; Kouri,

J.B.; Ramırez, J.T.; et al. The bactericidal effect of silver nanoparti-

cles. Nanotechnology 2005, 16, 2346.

15. Kim, J.S.; Kuk, E.; Yu, K.N.; Kim, J.H.; Park, S.J.; Lee, H.J.;; et al

Antimicrobial effects of silver nanoparticles. Nanomed. Nanotechnol.

Biol. Med. 2007, 3, 95–101.

16. McFarland, A.D.; Van Duyne, R.P. Single silver nanoparticles as

real-time optical sensors with zeptomole sensitivity. Nano Lett.

2003, 3, 1057–1062.

17. Wang, C.; Luconi, M.; Masi, A.; Fernandez, L. Silver nanoparticles as

optical sensors. In: Pozo-Perez, D., ed. Silver Nanoparticles, In Tech:

Rijeka, Croatia, 2010, Chapter 12, pp. 225–256.

18. Jana, N.R.; Sau, T.K.; Pal, T. Growing small silver particle as redox

catalyst. J. Phys. Chem. B 1999, 103, 115–121.

19. Manikam, V.R.; Cheong, K.Y.; Razak, K.A. Chemical reduction

methods for synthesizing Ag and Al nanoparticles and their respective

nanoalloys. Mater. Sci. Eng. B 2011, 176, 187–203.

20. Lin, C.A.; Tsai, H.C.; Tung, C.C. Preparation of silver nanoparticles=

pseudo-thermoplastic polyvinyl alcohol (PT-PVA) films by the

synchronous chemical reduction method. Polym.-Plast. Technol.

Eng. 2009, 48, 1171–1175.

21. Bajpai, S.; Bajpai, M.; Sharma, L. In situ formation of silver nanopar-

ticles in poly (N-isopropyl acrylamide) hydrogel for antibacterial

applications. Design. Monom. Polym. 2011, 14, 383–394.

22. Khanna, P.; Singh, N.; Charan, S.; Subbarao, V.; Gokhale, R.;

Mulik, U. Synthesis and characterization of Ag=PVA nanocomposite

by chemical reduction method. Mater. Chem. Phys. 2005, 93, 117–121.

23. Jung, R.; Kim, Y.; Kim, H.S.; Jin, H.J. Antimicrobial properties of

hydrated cellulose membranes with silver nanoparticles. J. Biomater.

Sci. Polym. Ed. 2009, 20, 311–324.

24. Eksik, O.; Erciyes, A.T.; Yagci, Y. In situ synthesis of oil based

polymer composites containing silver nanoparticles. J. Macromol.

Sci. Pt. A: Pure Appl. Chem. 2008, 45, 698–704.

25. Sheng, R.S.; Zhu, L.; Morris, M.D. Sedimentation classification of

silver colloids for surface-enhanced Raman scattering. Anal. Chem.

1986, 58, 1116–1119.

26. Munro, C.; Smith, W.; Garner, M.; Clarkson, J.; White, P. Character-

ization of the surface of a citrate-reduced colloid optimized for use

as a substrate for surface-enhanced resonance Raman scattering.

Langmuir 1995, 11, 3712–3720.

27. Xue, C.; Metraux, G.S.; Millstone, J.E.; Mirkin, C.A. Mechanistic

study of photomediated triangular silver nanoprism growth. J. Amer.

Chem. Soc. 2008, 130, 8337–8344.

28. Singh, G.; Patankar, R.B.; Gupta, V.K. The preparation of polymer=

silver nanocomposites and application as an antibacterial material.

Polym.-Plast. Technol. Eng. 2010, 49, 1329–1333.

890 I. RATHNAYAKE ET AL.

Dow

nloa

ded

by [

Uni

vers

iti S

ains

Mal

aysi

a] a

t 00:

55 0

9 Ju

ly 2

013

29. Rathnayake, I.; Ismail, H.; Azahari, B.; Darsanasiri, N.D.;

Rajapakse, S. Synthesis and characterization of nano-silver incorpor-

ated natural rubber latex foam. Polym.-Plast. Technol. Eng. 2012, 51,

605–611.

30. Rathnayake, W.G.I.U.; Ismail, H.; Baharin, A.; Darsanasiri,

A.G.N.D.; Rajapakse, S. Synthesis and characterization of nano silver

based natural rubber latex foam for imparting antibacterial and

anti-fungal properties. Polym. Test. 2012, 31, 586–592.

31. El-Ola, S.M.A. New approach for imparting antimicrobial properties

for polyamide and wool containing fabrics. Polym.-Plast. Technol.

Eng. 2007, 46, 831–839.

32. El-Ola, S.M.A. Recent developments in finishing of synthetic fibers for

medical applications. Design. Monom. Polym. 2008, 11, 483–533.

33. Cockerill, F.R.; Clinical and Laboratory Standards Institute.

Performance Standards for Antimicrobial Susceptibility Testing.

20th Informational Supplement. Clinical and Laboratory Standards

Institute (CLSI): Wayne, PA, 2010.

34. Abdel-Mohsen, A.M.; Hrdina, R.; Burgert, L.; Krylova, G.; Abdel-

Rahman, R.M.; Krejcova, A.; et al. Green synthesis of hyaluronan fibers

with silver nanoparticles. Carbohydr. Polym. 2012, 89, 411–422.

35. Mulvaney, P. Surface plasmon spectroscopy of nanosized metal parti-

cles. Langmuir 1996, 12, 788–800.

36. Lee, K.S.; El-Sayed, M.A. Gold and silver nanoparticles in sensing

and imaging: sensitivity of plasmon response to size, shape, and metal

composition. J. Phys. Chem. B 2006, 110, 19220–19225.

37. Kelly, K.L.; Coronado, E.; Zhao, L.L.; Schatz, G.C. The optical

properties of metal nanoparticles: the influence of size, shape, and

dielectric environment. J. Phys. Chem. B 2003, 107, 668–677.

38. Balan, L.; Malval, J.P.; Schneider, R.; Burget, D. Silver nanoparticles:

new synthesis, characterization and photophysical properties. Mater.

Chem. Phys. 2007, 104, 417–421.

39. Smitha, S.; Nissamudeen, K.; Philip D.; Gopchandran K. Studies on

surface plasmon resonance and photoluminescence of silver nanopar-

ticles. Spectrochim. Acta Pt. A: Molecul. Biomol. Spectrosc. 2008, 71,

186–190.

40. Kamat, P.V. Photophysical, photochemical and photocatalytic aspects

of metal nanoparticles. J. Phys. Chem. B 2002, 106, 7729–7744.

41. Lammle, W. Particle size and stability analysis in turbid suspensions

and emulsions with Photon Cross Correlation Spectroscopy, PCCS.

VDI-Berichte: Germany, 2008, 2027:97–103.

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