Colloids and Surfaces B: Biointerfaces 80 (2010) 4550

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Colloids and Surfaces B: Biointerfaces

journa l homepage: www.e lsev ier .com

Banana peel extract mediated synthesis of gold n

Ashok Ba , Sma Institute of Bi Indiab DST Unit on N

a r t i c l

Article history:Received 24 NReceived in reAccepted 20 MAvailable onlin

Keywords:BiosynthesisBanana peel exGold nanopartSEM (scanningFTIR

by u, crusof nant, chd colrevem. Scoffeeorks tpectrolvemcles d

1. Introduction

Gold namaterials. Tplasmon restability [1]hexagons, ousing differbehavior ofcrystals or mcatalysis, optics, imagin

It is thuseveral appniques is oas photolittechniques[8,9]. Suchoften involveffective mifundamenta

Corresponsity of Pune, Gfax: +91 20 25

E-mail add

depend on the procedures that are employed or on the nature ofthe mediating molecules [1012]. For example, a simple physi-

0927-7765/$ doi:10.1016/j.noparticles are some of the most extensively studiedhese can be easily synthesized, exhibit intense surfacesonance and display high chemical as well as thermal. A variety of gold structures including rods, triangles,ctagons, cubes and nanowires can be synthesized byent techniques [25]. Studies on the morphologicalgold nanostructures and their evolution into micro-icrowires are signicant because of their wide use intics, optical electronics, microelectronics, biodiagnos-g, biological and chemical sensing techniques [1,6,7].s evident that nanoparticles and microstructures havelications and their synthesis by using simple tech-f prime importance. Micro-patterning methods suchhography and nano-imprinting are the conventionalthat are used for the fabrication of microstructuresmethods however, are complex, cost-intensive ande multiple steps. The development of robust and cost-cropatterning methods are thus an important aspect ofl research in this area. Self-assembling processes often

ding author at: Institute of Bioinformatics and Biotechnology, Univer-aneshkhind Road, Pune 411 007, India. Tel.: +91 20 25691333;690087.ress: smita@unipune.ernet.in (S. Zinjarde).

cal method using a silicon pore template has been developed forthe fabrication of monodisperse gold microwires [13]. In addition,chemicals such as citrate and amines have also been successfullyemployed for their production [14,15]. In the recent years, the useof natural and modied polysaccharides for the synthesis of goldmicrocrystals varying in size and shape has become a popular alter-native. In particular, chitosan and cellulose have been successfullyused for the fabrication of gold nanoparticles and microstructures[16,17].

To the best of our knowledge, the use of naturally available agri-cultural waste material has not been investigated so far, for suchapplications. Banana peels are a classical example of such abun-dantly available natural material. India is the largest producer ofbananas and FAO sources estimate that 21.77 million metric tonsof bananas are cultivated annually. Such estimates for the world-wide production are several folds higher. The peels of banana areusually discarded. They are mainly composed of natural polysac-charides [18]. Their medicinal value has been explored [19] andthey have also been used as substrates for the production of fungalbiomass [20]. Another application includes their use in the adsorp-tionofheavymetals fromwater [21]. In this study,we report anovelgreen biological route for the synthesis of nanoparticles and alsodemonstrate their assembly into microcubes and microwires (dueto the coffee ring phenomenon) by using the banana peel extract(BPE)powderasa reducingmaterial. The structureshavebeenchar-

see front matter 2010 Elsevier B.V. All rights reserved.colsurfb.2010.05.029nkara, Bhagyashree Joshia, Ameeta Ravi Kumara,b

oinformatics and Biotechnology, University of Pune, Ganeshkhind Road, Pune 411 007,anoscience, Department of Physics, University of Pune, Pune 411 007, India

e i n f o

ovember 2009vised form 16 May 2010ay 2010e 27 May 2010

tracticleselectron microscope)

a b s t r a c t

Gold nanoparticles were synthesizedfriendly green material. The boiledto reduce chloroauric acid. A varietyaltered with respect to pH, BPE conteThe reaction mixtures displayed viviDynamic light scattering (DLS) studiessynthetic conditionswas around 300netry (EDS) conrmed these results. A cinto microcubes and microwire netwtion studies of the samples revealed s(FTIR) spectroscopy indicated the invprocess. The BPE mediated nanopartitested fungal and bacterial cultures./ locate /co lsur fb

anoparticles

ita Zinjardea,b,

sing banana peel extract (BPE) as a simple, non-toxic, eco-hed, acetone precipitated, air-dried peel powder was usednoparticles were formed when the reaction conditions wereloroauric acid concentration and temperature of incubation.ors and UVvis spectra characteristic of gold nanoparticles.aled that the average size of the nanoparticles under standardanning electronmicroscopy and energy dispersive spectrom-ring phenomenon, led to the aggregation of the nanoparticlesowards the periphery of the air-dried samples. X-ray diffrac-a that were characteristic for gold. Fourier transform infra redent of carboxyl, amine and hydroxyl groups in the syntheticisplayed efcient antimicrobial activity towards most of the

2010 Elsevier B.V. All rights reserved.

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46 A. Bankar et al. / Colloids and Surfaces B: Biointerfaces 80 (2010) 4550

acterized by using UVvis spectroscopy, SEM-EDS, XRD and FTIRanalysis. In addition, an application (antimicrobial activity) of thesynthesized nanoparticles has also been demonstrated.

2. Experim

2.1. Prepara

BananathoroughlyThe boiledwater and tcloth. The acetone. That 1000 rpmfurther exp

2.2. Synthemicrocubes

For all th(HAuCl4) in10mg of BPunless othewater bath fvals and thwere charathesis was c(10mgBPE,of the goldHAuCl4 fromtration waschloroauriceffect of temcontainingbated at 40triplicates a

2.3. Characmicrowires

The goldspectrophotion mixtur3.0) was an(Beckman CScanning eformed on pon siliconwJSM-6360Awas usedalso analyzresentativemeasuremeSi (111) wagold salt (coout in the trand a D 8 A

2.4. FTIR an

In orderder surfacemicrostructlier by us [2HAuCl4) an

isual observations and UVvis absorption spectra of reaction mixtures (a)ent pH values [(A) pH 2.0, (B) pH 3.0, (C) pH 4.0, (D) pH 5.0 and (E) HAuCl4and (b) with varying concentrations of gold chloride (mM) [(A) 1.0, (B) 0.5,and (D) 0.125].

lt)were independently dried and blendedwith KBr to obtaint. The FTIR spectra were collected at resolution of 4 cm1 innsmission mode (4000400 cm1) using a Shimadzu FTIRphotometer (FTIR 8400).

tifungal and antibacterial activity

o pathogenic strains of Candida albicans (BX and BH) wereo determine the antifungal activity of the gold nanoparti-tock cultures of fungal strains were maintained on MGYP(malt extract, 3.0; peptone, 10.0; dextrose, 10.0 g l1 ofd water). Different bacterial cultures including Citrobacter(MTCC 1657), Escherichia coli (MTCC 728), Proteus valgaris426), Pseudomonas aeruginosa (MTCC 728), Enterobacter

nes (MTCC 111) and Klebsiella sp. were used to determine thecterial activity of gold nanoparticles. The bacterial culturesaintained on Nutrient Agar (NA) slants (peptone, 5.0; meat

t, 1.0; yeast extract 2.0; sodium chloride, 5.0; agar 15.0 g l1

illed water).antimicrobial activity of the nanoparticle was determinedeading 100l of fungal or bacterial cultures (containinglsml1) on MGYP or NA plates, respectively. Freshly pre-nanoparticle samples derived from the reaction mixturesing 10mg BPE, 1.0mM chloroauric acid, pH 5.0 incubated(50l) were added into the wells in the seeded agar plates.

l samples lacking the chloroauric acid were used to assesstimicrobial activity of the BPE. The test and control samplesental

tion of banana peel extract (BPE) powder

(Musa paradisiaca) peels were collected and washed. They were boiled in distilled water at 90 C for 30min.banana peels (100g) were crushed in 100ml distilledhe resultant extract was ltered through a clean muslinltrate was precipitated with equal volumes of chillede resulting precipitate was collected by centrifugationfor 5min, air-dried into a powdered form and used for

eriments.

sis of gold nanoparticles and their assembly intoand microwires

e experiments, the source of gold was chloroauric aciddistilled water. Typical reaction mixtures containedE powder in 2ml of chloroauric acid solution (1mM)rwise stated. The mixtures were incubated at 80 C in aor3min. Theseweremonitored fordifferent time inter-e nanoparticles and microstructures that were formedcterized further. The effect of pH on nanoparticle syn-arried out by adjusting the pH of the reaction mixtures1.0mMchloroauric acid) to2.0, 3.0, 4.0 or 5.0. Theeffectsalt was determined by increasing the concentration of

0.125, 0.25, 0.5 or 1.0mM. The BPE powder concen-varied (0.5, 1.0, 2.0, 4.0 or 10.0mg) while keeping theacid concentration at a level of 1.0mM. To study theperature on nanoparticle synthesis, reaction mixtures

10mg BPE, and 1.0mM HAuCl4 at pH 3.0 were incu-, 60, 80 or 100 C. All experiments were carried out innd representative data is presented here.

terization of gold nanoparticles, microcubes and

nanoparticles were characterized by using a UVvistometer (Jasco V-530). The size of particles in the reac-es (containing 10mg BPE, 1.0mM chloroauric acid, pHalyzed by using the dynamic light scattering equipmentoulter DELSA Nano CNano Particle Size Analyzer).

lectron microscopy and elemental analysis were per-latinum coated samples that were previously air-driedafers. An analytical scanning electronmicroscope (JOEL) equipped with energy dispersive spectrometer (EDS)[22,23]. Control samples lacking the gold salt wereed. All samples were analyzed in triplicates and rep-micrographs are included here. X-ray diffraction (XRD)nts of thoroughly dried thin lms of nanoparticles onfers were carried out. In addition, samples lacking thentrol samples)were also analyzed. Analysiswas carriedansmission mode with Cu K radiation using =1.54dvanced Brucker instrument.

alysis

to determine the functional groups on the BPE pow-and their possible involvement in the synthesis of goldures, FTIR analysis was carried out as described ear-4]. Control samples (BPE powder before reaction withd the test samples (BPE powder after reaction with the

Fig. 1. Vat differcontrol](C) 0.25

gold saa pellethe traspectro

2.5. An

Twused tcles. Sslantsdistillekosari(MTCCaerogeantibawere mextracof dist

Theby spr104 celparedcontainat 80 CControthe an

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A. Bankar et al. / Colloids and Surfaces B: Biointerfaces 80 (2010) 4550 47

Fig. 2. Scanninacid (e) and (f)100, inset ba

were allowther incubawhen a zonincubationcarried outhere.

3. Results

3.1. Visual

The reacof incubatioa variety ofsynthesis iride solutioout at pH 2at pH 3.04.0 [Fig. 1a[Fig. 1a (D)shown in Fof 500600also reportechloroauricg electron micrographs of gold nanoparticles (a) and (b); microwire networks at the perwith 1.0mMchloroauric acid (a) ismagnied 10,000, inset bar represents 1m(b) ismar represents 100m (d) and (f) are magnied 2000, inset bar represents 10m.

ed to diffuse for 15min at 4 C and the plates were fur-ted at 37 C for 2448h. The test was scored positivee of inhibition was observed around the well after theperiod. All experiments on antimicrobial activity werein triplicates and representative gures are presented

and discussion

observations and UVvis spectroscopy

tion mixtures developed an array of colors after 3minn under different conditions indicating the synthesis ofgold nanoparticles. The effect of pH on nanoparticle

s shown in Fig. 1a. The yellow color of gold chlo-n turned to brown when the reaction was carried.0 [Fig. 1a (A)]. A purplish-pink color was observed

[Fig. 1a (B)]. A ruby red color was obtained at pH(C)] and a dark reddish color developed at pH 5.0

]. The UVvis spectra of the reaction mixtures are alsoig. 1a. In each case, a peak was observed in the rangenm suggesting the synthesis of gold nanoparticles asd earlier for other biological systems [25]. The controlacid solution (without BPE) did not display the charac-

teristic peaoccur.

Fig. 1b stionsonnanwith 1.0mMsistent withthe reactionchloroauricplayed a peof gold chlo(BD)].

There wcontents of

As statewas observlight ruby r2.0mgml1

4mgml1 aBPE powdeobserved.

The incution. For exayellowish-bpinkish-broiphery due to coffee ring effect (c) and (d) with 0.25mM chloroauricgnied 30,000, inset bar represents 0.5m(c) and (e) aremagnied

k [Fig. 1a (E)] indicating that abiotic reduction did not

hows the effect of varying chloroauric acid concentra-oparticle synthesis. Apurplish-pink colorwasobservedconcentration of the gold salt [Fig. 1b (A)]. This is con-the visual observations made in Fig. 1a (B) wherein,mixture composition was similar (10mg BPE, 1.0mMacid, pH 3.0). The UVvis spectra of the tubes also dis-

ak in range of 510600nm.With 0.5, 0.25 and 0.125mMride, varying shades of purple were observed [Fig. 1b

as a variation in nanoparticle synthesis with increasingthe BPE.d earlier, with 10mgml1 of BPE, a purplish-pink colored [as also seen in Fig. 1a (B) and b (A)]. Dark anded colors were observed at a concentration of 1.0 or. The reaction mixture turned dark reddish brown withnd a pink color was developed with 5mgml1 of ther. Signature peaks indicative of nanoparticles were also

bation temperature affected the process of gold reduc-mple, anorangish-browncolorwasobservedat 40 C.Arown color was developed at 60 C. Purplish-pink andwn colors were observed at 80 C and 100 C, respec-

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48 A. Bankar et al. / Colloids and Surfaces B: Biointerfaces 80 (2010) 4550

tively. The peak characteristics for gold nanoparticles were alsoobserved. The visual observations and UVvis spectra were thusindicative of nanoparticle synthesis. Gold nanoparticles are knownto display vivid colors due to the phenomenon of surface plasmonresonance (

3.2. Scanni(SEM-EDS) a

The SEMreaction prgraphs of apowder andpH 3.0 are sscale gold pat a magnistructures wlier reportsmediating ttures [26].was also coments reveThis is conb.

The reacsample wasfee ring phevaporatedthe outer edare also knis a report ocharacteristnanoparticlThey forme(white arrotions (Fig. 3revealed tharranged inpresence of(blackarrownanoparticlinto microc

There arFor exampl(sized 101addition, cysize gold cu12m [16microcubesand in the rthe earlier tto the coffelong (Fig. 2nanowire nRhodopseudobservedwters of theserange (506

There isthe synthesadvantagerather thanbeen an incing biopolycontrollingpeels are la

a) Rebes anrocub

miceis kner hand, has been used to stabilize chemically synthesizedllic nanoparticles of gold and platinum [34]. These natu-ymers present in BPE may be providing a template for thebly of nanoparticles into micronetworks. Literature surveyown that biosynthesis of gold nanoplates and nanocubes aremon feature. However, the formation of large microcubesm) and their assembly into long networks is an unusual

menon that has not been hitherto reported. The micronet-so assembled in turn, may have applications in a variety of

EDS attachment on the SEM provided chemical analysis ofdof viewaswell as spotanalysesofminuteparticles andcon-the presence of specic elements. Fig. 3a is a representativethe spotEDSanalysis. TheSEM-EDSanalysis displayed signa-ectra for gold and thus convincingly evidenced the presencenoblemetal in themicrocubes andmicrowires. These resultssistent with other reports on the EDS analysis of gold struc-ynthesized by using extracts derived from the fruits of pearleaves of Magnolia kobus or Diopyros kaki [31,35].

ray diffraction (XRD) analysis

presentative XRD prole of the gold microcubes displayinguctural information and crystallinity are shown in Fig. 3b.rol thin lm of gold chloride before reaction did not showaracteristic peaks. After reaction, the diffraction peaks at.1, 44.5, 64.21 and 77.78 assigned to the (111), (2 00),and (311) planes of a faced centre cubic (fcc) lattice ofere obtained. The XRD analysis showed predominant peaks1) and (200) indicative of the presence of microcubesSPR) as also reported earlier [16,22,23].

ng electron microscope-energy dispersive spectrumnalysis

analysis was used to determine the structure of theoducts that were formed. Representative SEM micro-ir-dried reaction mixtures containing 10mg of BPE0.25, 0.5 or 1.0mM of chloroauric acid incubated at

hown in Fig. 3af. Fig. 3a shows the presence of nano-articles (white arrows) and nanoplates (black arrows)cation of 10,000. At a magnication of 30,000, theirere distinct (Fig. 3b). This is in agreement with ear-

on biological material such as the lemon grass extracthe reduction of chloroaurate ions into triangular struc-In the present study, the particle size distributionnrmed by DLS studies. The results of these experi-aled that the average particle size was around 300nm.sistent with the SEM results obtained in Fig. 2a and

tionmixtureswere air-dried on siliconwaferswhen theprepared for the SEM studies. This resulted in a cof-

enomenon. When liquids containing ne particles areon a at surface, the particles tend to accumulate alongge and form typical structures [27]. Gold nanoparticlesown to display this phenomenon. For example, theren the formation of colloidal gold lms that exhibit theic coffee ring feature [28]. In the present study, the goldesaccumulated towards theperipheryof thedrieddrop.d micronetworks as well as dendrite-like structuresws) that could be observed even at low magnica-c and e). High magnications images (1000 or 2000)at the networks were composed of gold microcubesa specic array (Fig. 3d and f). Fig. 3f also shows thetriangles and hexagons in the patterned microwiress). BPE thus consistentlymediated the synthesis of gold

eswhichdue to the coffee ringphenomenonaggregatedubes and networks.e a few reports on the biological synthesis of nanocubes.e, there is a report on the production of such structures00nm) by the bacterium, Bacillus licheniformis [29]. Insteine grafted chitosan has also been used to synthe-bes. These cubes had an edge length in the range of]. In comparison to these two reports, the size of thedue to the coffee ring effect with BPE were much largerange of 1020m (Fig. 2b, d and f). Moreover, unlikewo reports [16,29], the cubes formed in this study (duee ring effect) aggregated into networks that were verya, c and e). There is a report on the formation of goldetworks by the cell-free supernatant of the bacteriumomoas capsulata [30]. Such structures were particularlyithhigher concentrations of the gold salt and thediame-polycrystalline gold nanowires were in the nanometer0nm) unlike the results obtained in the current study.a recent report on the use of peach fruit extract foris of hexagonal or triangular gold nanoplates [31]. Anof the present study is the use of waste banana peelsthe edible fruit for the synthetic process. There has

reasing interest in the use of soluble polymers includ-mers as soft templates for directing crystal growth andself-assembly of inorganic nanoparticles [32]. Bananargely composed of hot water soluble pectin, cellulose

Fig. 3. (microcugold mic

and helulosethe othbimetaral polassemhas sha com(1020phenoworkselds.

Thetheelrmedplot ofture spof thisare contures sor the

3.3. X-

A rethe strA contthe ch2 =38(220)gold wat (11presentative spot EDS prole conrming the presence of gold ind microwire networks. (b) Representative XRD prole of thin lmes and microwire networks.

lluloses that constitute nearly 80% of themass [33]. Cel-own to mediate nanoparticle synthesis [17]. Pectin, on

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A. Bankar et al. / Colloids and Surfaces B: Biointerfaces 80 (2010) 4550 49

Fig. 4.

and microwdisplayed a[17,31].

3.4. FTIR an

FTIR hasinvolvemenactions. Thiwerepresenthe synthesder (not trereecting thin the inten(after reactipeak was obstretching v[36]. This pesible involvsynthesis. Tto the NH[37]. The pgroups coucesses. Thestretching iA shift in thble involvemnanoparticlwas suggesplane deforgroups in tassigned toto 1333 cm

with chloroceousmattenanoparticlcomposedogroups assoter may thumicrostruct

3.5. Antifun

In additterned micthese BPE magents. Suc

epresalbicans BX, (b) C. albicans BH, (c) Shigella sp., (d) Enterobacter aerogenes, (e)a sp. and (f) Pseudomonas aeruginosa.

for antimicrobial activity towards test fungal and bacterial. BPE on its own did not display antimicrobial activity. Fig. 5ashows the zones of inhibition that were observed with theains of C. albicans. In all these gures, the white arrows indi-e wells and the black arrows represent the inhibition zones.cterial activity was observed against Shigella sp., C. kosari, E.algarisandE. aerogenes. Fig. 5candd is representative inhibi-nes observed with Shigella sp. and E. aerogenes, respectively.consistentwithanearlier report on theantimicrobial activitynanoparticles biosynthesized by the fungus Rhizopus oryzaewell as those synthesized chemically [41]. In the present

however, antibacterial activity was not observed with all theltures. For example, Klebsiella sp. and Ps. aeruginosawere noted by the gold nanoparticles (Fig. 5e and f). There are a fewFTIR spectra of BPE powder () before and after (. . .) reaction.

ires displaying fcc lattice structure. The XRD patternsre consistent with earlier reports on microstructures

alysis

emerged as a valuable tool for understanding thet of surface functional biological groups in metal inter-s technique was applied to determine the groups thatt on theBPEpowder and topossibly predict their role inis of gold microstructures. Control spectra of BPE pow-atedwith chloroauric acid) displayed a number of peakse complex nature of the powder. There was a variationsity of bands in different regions when test samplesonwithchloroauric acid)wereanalyzed (Fig. 4).Amajorserved at 2930 cm1 that could be assigned to the CHibrations of methyl, methylene and methoxy groupsak shifted from 2930 to 2888 cm1 suggesting the pos-ement of the aforementioned groups in nanoparticlehe peak located at around 2353 cm1 was attributedstretching vibrations or the C=O stretching vibrationseak shift from 2353 to 2357 cm1 revealed that theseld also be involved in the nanoparticle synthetic pro-peak located at 1640 cm1 was assigned to the C=On carboxyl or C=N bending in the amide group [38,39].is peak (from 1640 to 1670 cm1) indicated the possi-ent of carboxyl or amino groups of the BPE powder in

e synthesis. Thevibration shift around14451443 cm1

tive of the involvement of aliphatic and aromatic (CH)mation vibrations of methyl, methylene and methoxyhe process [36]. The band observed at 1375 cm1 wasCN stretching or the OH bending [38] and its shift

Fig. 5. RCandidaKlebsiell

testedstrainsand btwo strcate thAntibacoli,P. vtion zoThis isof gold[40] asstudy,test cuinhibit1 implicated the role of these groups in the interactionauric acid. These results also indicate that the proteina-r in the peelsmay also be participating in the process ofe synthesis. As stated earlier, banana peels are mainlyf pectin, cellulose andhemicellulose [18,33]. Functionalciatedwith these polymers and the proteinaceousmat-s be involved in reducing the gold salt and stabilizingures.

gal and antibacterial activity of gold nanoparticles

ion to the several possible applications that the pat-rocubes may display, we have investigated the use of

ediated gold nanoparticles as possible antimicrobialh BPE mediated gold nanoparticles were immediately

reports in theffective agsized couldantibacteria

4. Conclus

In conclrial for theA variationvariety of nspectra. BPcles into mgold nanoptowards thentative results of antimicrobial activity of nanoparticles against (a)e literature on the inability of gold nanoparticles beingainst test bacteria [42]. The nanoparticles thus synthe-also be applied as antifungal agents and as selectivel agents.

ions

usion, BPE could be used as an efcient green mate-rapid and consistent synthesis of gold nanoparticles.in reaction conditions brought about the synthesis of aanoparticles displaying vivid colors and typical UVvisE mediated structured patterning of the nanoparti-icrocubes and microwire networks. The BPE derivedarticles displayed antifungal and antibacterial activitye test pathogenic fungi and most of the bacterial cul-

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50 A. Bankar et al. / Colloids and Surfaces B: Biointerfaces 80 (2010) 4550

tures. This simple, low cost, non-toxic, eco-friendly, abundantlyavailable green agricultural waste material could thus be used asan efcient alternative to the cost intensive conventionalmicropat-terningmethods. Themicrocrystals andnetworks generatedby thisnon-conventional method could have a variety of applications inthe future. Moreover, this system could also be used as a model forunderstanding the mechanism of microstructure evolution medi-ated by biological systems.

Acknowledgements

AB wishes to thank Council of Scientic and Industrial Research,India for Senior Research Fellowship (CSIRSRF). The authors thankDepartment of Science and Technology, India for funding theNanoscience Unit at University of Pune and University GrantsCommission, India, for nancial support to the Institute of Bioin-formatics and Biotechnology.

References

[1] T. Jennings, G. Strouse, Adv. Exp. Med. Biol. 620 (2007) 34.[2] N.R. Jana, L. Gearheart, C.J. Murphy, Adv. Mater. 13 (2001) 1389.[3] L. Wang, X. Chen, J. Zhan, Y. Chai, C. Yang, L. Xu, W. Zhuang, B. Jing, J. Phys.

Chem. B 109 (2005) 3189.[4] D. Seo, J.C. Park, H. Song, J. Am. Chem. Soc. 128 (2006) 14863.[5] N. Pazos-Prez, D. Baranov, S. Irsen,M. Hilgendorff, L.M. Liz-Marzn,M. Giersig,

Langmuir 24 (2008) 9855.[6] K.S. Lee, M.A. EL-Sayed, J. Phys. Chem. B 110 (2006) 19220.[7] P.K. Jain, X. Huang, I.H. El-Sayed,M.A. EL-Sayed, Acc. Chem. Res. 41 (2008) 1578.[8] B.D. Gates, Q. Xu, M. Stewart, D. Ryan, C.G. Willson, G.M. Whitesides, Chem.

Rev. 105 (2005) 1171.[9] Z. Nie, E. Kumacheva, Nat. Mater. 7 (2008) 277.

[10] M.C. Daniel, D. Astruc, Chem. Rev. 104 (2004) 293.[11] R.T. Shenhar, B. Norsten, V.M. Rotello, Adv. Mater. 17 (2005) 657.[12] E. Katz, I. Willner, Angew. Chem. Int. Ed. 43 (2004) 6042.[13] S. Matthias, J. Schilling, K. Nielsch, F. Mllar, R.B. Wehrspoh, U. Gsele, Adv.

Mater. 14 (2002) 1618.

[14] T. Wang, R. Zheng, X. Hu, L. Zhang, S. Dong, J. Phys. Chem. B 110 (2006) 14179.[15] X. Liu, N. Wu, B.H. Wunsch, R.J. Barsotti Jr., F. Stellacci, Small 2 (2006) 1046.[16] Y. Ding, G. Gu, X. Xia, Q. Huo, J. Mater. Chem. 19 (2009) 795.[17] Z. Li, A. Friedrich, A. Taubert, J. Mater. Chem. 18 (2008) 1008.[18] T. Happi Emaga, C. Robert, S.N. Ronkart, B. Wathelet, M. Paquot, Bioresour.

Technol. 99 (2007) 4346.[19] H.S. Parmar, A. Kar, J. Med. Food. 11 (2008) 376.[20] J.P. Essien, E.J. Akpan, E.P. Essien, Bioresour. Technol. 96 (2005) 1451.[21] G. Annadurai, R.S. Juang, D.J. Lee, Water Sci. Technol. 47 (2003) 185.[22] M. Agnihotri, S. Joshi, A.R. Kumar, S. Zinjarde, S. Kulkarni, Mater. Lett. 63 (2009)

1231.[23] P.S. Pimprikar, S.S. Joshi, A.R. Kumar, S.S. Zinjarde, S.K. Kulkarni, Colloids Surf.

B: Biointerf. 74 (2009) 309.[24] A.V. Bankar, A.R. Kumar, S.S. Zinjarde, J. Hazard. Mater. 170 (2009) 487.[25] A. Ahmad, S. Senapati, M.I. Khan, R. Kumar, R. Ramani, V. Srinivas, M. Sastry,

Nanotechnology 14 (2003) 824.[26] S. Shiv Shankar, A. Rai, B. Ankamwar, A. Singh, A. Ahmad, M. Sastry, Nat. Mater.

3 (2004) 482.[27] L. Chen, J.R.G. Evans, Langmuir 25 (2009) 11299.[28] K.W. Kho, Z.X. Shen, H.C. Zeng, K.C. Soo, M. Olivo, Anal. Chem. 77 (2005) 7462.[29] K. Kalishwarlal, V. Deepak, S.R.K. Pandian, S. Gurunathan, Bioresour. Technol.

100 (2009) 5356.[30] S. He, Y. Zhang, Z. Gou, N. Gu, Biotechnol. Prog. 24 (2008) 476.[31] G.S. Ghodake, N.G. Deshpande, Y.P. Lee, E.S. Jin, Colloids Surf. B: Biointerf.

(2009), doi:10.1016/j.colsurfb.2009.09.040.[32] S.H Yu, S.F. Chen, Curr. Nanosci. 2 (2006) 81.[33] H.N. Chanakya, I. Sharma, T.V. Ramachandra, Waste Manag. (2008),

doi:10.1016/j.wasman.2008.09.014.[34] M Kajita, K. Hikosaka, M. Iitsuka, A. Kanayama, N. Toshima, Y. Miyamoto, Free

Radic. Res. 41 (2007) 615.[35] J.Y. Song, H.K. Jang, B.S. Kim, Proc. Biochem. 44 (2009) 1133.[36] N. Feng, X. Guo, S. Liang, J. Hazard. Mater. 164 (2009) 1286.[37] N.V. Farinella, G.D. Matos, M.A.Z. Arruda, Bioresour. Technol. 98 (2007) 1940.[38] S. Li, X. Jin-Ian, H.E. Huan, N.I.E. Zhen-Yuan, Q.I.U. Guan-Zhou, J. Cent. South

Univ. Technol. 14 (2007) 157.[39] S. Qaiser, A.R. Saleemi, M. Umar, J. Hazard. Mater. 166 (2009) 998.[40] S.K. Das, A.R. Das, A.K. Guha, Langmuir 25 (2009) 8192.[41] Y. Zhang, H. Peng, W. Huang, Y. Zhou, D. Yan, Colloids Interf. Sci. 325 (2008)

371.[42] A.Dror Ehre,H.Mamane, T. Belenkova,G.Markovich, A. Adin, J. Colloid Interface

Sci. 339 (2009) 521.

Banana peel extract mediated synthesis of gold nanoparticlesIntroductionExperimentalPreparation of banana peel extract (BPE) powderSynthesis of gold nanoparticles and their assembly into microcubes and microwiresCharacterization of gold nanoparticles, microcubes and microwiresFTIR analysisAntifungal and antibacterial activity

Results and discussionVisual observations and UVvis spectroscopyScanning electron microscope-energy dispersive spectrum (SEM-EDS) analysisX-ray diffraction (XRD) analysisFTIR analysisAntifungal and antibacterial activity of gold nanoparticles

ConclusionsAcknowledgementsReferences