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1. Introduction

of methods, including chemical and physimost of the methods may successfully pdened nanoparticles, these methods are

ironmeand physicas [13er alten studra [4],

The genus Rosa includes 200 species and more than 18,000

varieties, the main rose producers in the world obtain fromR. damascena. R. damascena (Rosaceae) (Fig. 1) is a widely culti-

] and

ionale, bya red

nervine tonic properties can be formulated [30].

Contents lists available at ScienceDirect

.el

Physic

Physica E 44 (2011) 97104prime moieties involved in the reduction and capping process.E-mail address: s.m.ghoreishi@kashanu.ac.ir (S.M. Ghoreishi).cultivars [20]. Despite the large number of cultivated rose We can presume that the avanoids, polyphenolic and essentialoil, which are abundant in R. damascena appear to be responsiblefor accelerated reduction and capping of AuNPs and AgNPs.Essential oil is poorly water soluble and hence may not be among

1386-9477/$ - see front matter & 2011 Elsevier B.V. All rights reserved.

doi:10.1016/j.physe.2011.07.008

n Corresponding author. Tel.: 98 3615912395; fax: 98 3615912930.nanoparticles using leaf extract of Rosa rugosa [18] and Tanacetumvulgare (tansy) [19].

powder (this red powder is called Kushta Tila). After processingthe R. damascena extract using gold, a drug with cardiotonic andfor AgAuCu alloy nanoparticle synthesis. Recently, Philip et al.demonstrated green synthesis of gold and silver nanoparticlesusing Hibiscus rosa sinensis [14], Murraya Koenigii leaf-assisted[15], Mangifera indica [16] and Krishna tulsi [17]. Dubey et al.studied the synthesis and characterizations of silver and gold

[27], that can protect against cardiovascular diseases [28certain kinds of cancers [29].

Herbs and minerals are the integral parts of traditmedicine in many countries. In traditional Iranian medicinadding R. damascena extract to pure gold, they obtained[6], Cinnamommum camphora [7], Neem [8], Tamarind [9], Emblicaofcinalis [10], Clove [11] and Syzygium aromaticum [12] haveshown potential in reducing Au3 ions to form gold nanoparticles(Au) and silver nitrate (Ag) to form silver nanoparticles (Ag).However, Brassica juncea germinating seeds [13] have been used

leaves, nuts, seeds, owers and barks [24]. Quercetin mainlyoccurs in plants as glycosides, such as rutin and quercitrin. Overthe past years, avanoids have gained tremendous interestbecause of their protective effects on DNA damage [25], anti-inammatory [26] and their free radical scavenging activitiespotentially dangerous to the envorganisms such as microorganismsan alternative to chemical and pfriendly manner and green synthesi

Plant extracts may provide a bettproduction. Several plants have beenanoparticles. The extracts of Aloe vehesized using a varietycal methods. Althoughroduce pure and well-quite expensive and

nt. Use of biologicallant extracts could bel methods in an eco-].rnative to nanoparticleied for biosynthesis ofPapaya [5], Lemongrass

vated ornamental plant. Several therapeutic effects includinganti-inammatory, astringent, expectorant, laxative, cardiac tonicand aperients have been described for the ower extract ofR. damascena. Roses also have an economic importance for theirower as a source of natural fragrances and avorings [21]. Fouravanoids, quercetin, quercitrin, rutin and luteolin [22] and twopolyphenols, gallic acid and myricetin (Fig. 2) [23] were detectedand quantied in fresh owers of R. damascena. The owerscontain an essential oil with citronellol, nerol, geraniol andbeta-phenylethanol. Flavanoids and polyphenols naturally occurin the plant kingdom and generally present in fruits, vegetables,The metal nanoparticles have been syntGreen synthesis of silver and gold nanopprimary application in electrochemistry

Sayed M. Ghoreishi n, Mohsen Behpour, Maryam K

Department of Analytical Chemistry, Faculty of Chemistry, University of Kashan, Kasha

a r t i c l e i n f o

Article history:

Received 30 June 2011

Received in revised form

24 July 2011

Accepted 28 July 2011Available online 4 August 2011

a b s t r a c t

Biosynthesis and characte

ogy. In this paper, green sy

the ower extract of Ros

approach is simple, cost-e

an eco-friendly manner to

characterized using UVv

electrode using AuNPs (Au

0.1 M KCl and 5.0103 Mthe modied electrode an

journal homepage: wwwrticles using Rosa damascena and its

yatkashani

317-51167, Islamic Republic of Iran

tions of nanoparticles have become an important branch of nanotechnol-

esis of gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) using

mascena as a reducing and stabilizing agent, has been discussed. This

tive and stable for a long time, reproducible at room temperature and in

ain a self-assembly of AuNPs and AgNPs. The resulting nanoparticles are

EM, XRD and FT-IR spectroscopic techniques. A modied glassy carbon

s/GCE) was investigated by means of cyclic voltammetry in a solution of

e(CN)6]3/4. The results show that electronic transmission rate between

e(CN)6]3/4 increased.

& 2011 Elsevier B.V. All rights reserved.

sevier.com/locate/physe

a E

S.M. Ghoreishi et al. / Physica E 44 (2011) 9710498However, we restricted our attention to avanoids and polyphe-nols compounds due to its high antioxidant capacity. Naturalavanoids have been shown to serve as a reductant for theenlargement of Au nanoparticles [31] and the synthesis of Agnanoparticles in reverse micelles [32], and thus there is a possibi-lity that it may be responsible for the formation and growth ofAuNPs and AgNPs. Thus, this oxidized form of avanoids andpolyphenols may dictate the growth and capping of the AuNPsand AgNPs. It was understood that avanoids also prevent agglom-eration and stabilize the AuNPs in an aqueous solution [33].

In the present study, we rst report the synthesis of AuNPs andAgNPs by the reduction of gold and silver ions using R. damascena.R. damascena extract contains antioxidant compounds and act as

3

volume was adjusted to 50 mL with deionised water. The result-

Fig. 1. Photograph of R. damascena used in the biosynthesis.

O

O

O H

R

O H

O H

O H

O

OH

OH

OH

OH O

OH

OH

O

HOOH

OH

OH

Myricetin dica cillaG

Luteolin: R = H

Quercitrin: R = Rhamnopyranosyl

Rutin: R = Rutinoside

Quercetin: R = OH

Fig. 2. Flavanoids and polyphenols content in R. damascena extract.ing solution became brown in color after 5 min. Color intensityincreases with the increase in HAuCl4 3H2O and AgNO3 concen-trations at a xed volume fraction of extract.

2.4. Assembling of AuNPs modied glassy carbon electrode

The bare glassy carbon electrode (bare-GCE) was polished intoa mirror-like surface with 0.5 and 0.05 mm alpha Al2O3 and thenrinsed ultrasonically with water baths, so that any physicallyadsorbed species is removed. The cleaned glassy carbon electrodereducing agents, reversing oxidation by donating electrons andhydrogen ions. We can presume that the avanoids and poly-phenols, which are abundant in R. damascena extract showcharacteristic absorption peaks and appear to be responsible foraccelerated reduction and capping of R. damascena extract. Othercompounds of R. damascena are poorly water soluble and hencemay not be among prime moieties involved in the reductionprocess. Gold colloidal nanoparticles were used to realize amodied GCE and enhance electronic transmission rate betweenthe electrode and [Fe(CN)6]

3/4.

2. Experimental

2.1. Materials

Chloroauric acid (HAuCl4 3H2O) and silver nitrate (AgNO3)were obtained from Merck and used as received. A stock solutioncontaining 1103 M HAuCl4 3H2O and 1102 M AgNO3were prepared in deionised water. All other reagents were ofanalytical grade. R. damascena ower collected from Kashan, Iran,was cleaned thoroughly with deionised water and dried at 303 K.Then 10 g of R. damascena ower was passed through a sieve(30 mesh) and stirred with 100 mL deionised water at 300 K for5 min and ltered to get the extract.

2.2. Apparatus

The FT-IR spectra were recorded by a Perkin-Elmer FT-IRspectrophotometer. X-ray diffraction (XRD) measurements wererecorded using Rigaku D-max C III, X-ray diffractometer usingNi-ltered Cu Ka radiation (l1.5406 A). UVvis spectroscopymeasurements were carried out on Perkin-Elmer spectrophot-ometer operated at a resolution of 1 nm. TEM samples of the AuNPsand AgNPs synthesized using the R. damascena extract wereprepared by placing drops of the reaction mixture over carboncoated copper grids and allowing the solvent to evaporate. TEMimages were obtained on a Philips EM208 transmission electronmicroscope with an accelerating voltage of 100 kV. Voltammetricmeasurements were carried out using an Autolab potentiostat/galvanostat PGSTAT 35 (Eco chemie Utrecht, Netherlands) equippedwith GPES 4.9 software. The electrochemical cell was equippedwith a glassy carbon electrode (GCE) as the working, a platinumelectrode as the counter and an Ag/AgCl electrode as the referenceelectrode. All experiments were carried out at room temperature.

2.3. Synthesis of AuNPs and AgNPs

15 mL R. damascena ower extract was added to a vigorouslystirred 30 mL aqueous solution of HAuCl4 (1103 M) andstirred continuously for 2 min and the nal volume was adjustedto 50 mL with deionised water at room temperature. In a typicalreaction procedure, 10 mL of R. damascena ower extract wasadded to 30 mL of AgNO (1102 M) solution and the nalwas modied by dip coating, using immersion times (2 h) in the

colloidal nanoparticles solutions. The modied electrode waselectrochemically characterized by cyclic voltammetry (CV) in a0.1 M KCl solution that contains 5.0103 M [Fe(CN)6]3/4 .

3. Results and discussion

3.1. UVvis absorbance spectroscopy

UVvis spectroscopy is an important technique to ascertainthe formation and stability of nanoparticles in aqueous solution.Spectral analysis for the development of nanoparticles at differ-ent reaction conditions was observed using UVvis spectralanalysis. The reaction mixtures developed an array of colorsafter 2 min for AuNPs and 5 min for AgNPs of incubation under

different conditions indicating the synthesis of a variety ofAuNPs and AgNPs. The UVvis spectra of the reaction mixturesare also shown in Figs. 3 and 4. AuNPs and AgNPs gave sharppeak in the range of visible region of the spectrum. Fig. 3a and bshows the effect of varying R. damascena concentrations onAuNPs and AgNPs synthesis. With an increase in R. damascenaextract from 9 to 15 mL for AuNPs and 5 to 10 mL for AgNPs,consistently an increase in peak absorbance was found in UVvisspectrum. However, visual inspection of the solutions revealedcolor changes from light pink to deep red for AuNPs and darkyellow to brown for AgNPs with an increase of R. damascenaquantity in each reaction solution. It is well known that AuNPsand AgNPs exhibit lovely pink-ruby red and brown colors, andthese colors arise due to excitation of surface plasmon vibra-tions. The AuNPs and AgNPs surface plasmon band occurs in the

1.5

2.0

Wavelength (nm)

banc

e

c

fe

d

0.0

0.5

1.0

1.5

2.0

2.5

3.0

400Wavelength (nm)

Abs

orba

nce

a

d

c

b

gfe

450 500 550 600 650 700 7500.0

0.5

1.0

1.5

2.0

2.5

480

Abs

orba

nce

Wavelength (nm)

24 h

10 day

2 months

3 months

1.5

2.0

banc

e

3 months

2 months

10 day

580 680

S.M. Ghoreishi et al. / Physica E 44 (2011) 97104 99Fig. 3. (a) UVvis absorption spectrum of AuNPs at different R. damascena extractsquantity (30 mL HAuCl4 1103 M with 9, 10, 11, 12, 13, 14 and 15 mLR. damascena extract). (b) UVvis absorption spectrum of AgNPs at different

R. damascena extracts quantity (30 mL AgNO3 1102 M with 5, 6, 7, 8, 9 and0.0

0.5

1.0

380

Abs

or

a

b

430 480 530 580 630 68010 mL R. damascena extract).0.0

0.5

1.0

380

Abs

or

Wavelength (nm)

24 h

480 580

Fig. 4. (a) UVvis absorption spectrum of AuNPs recorded as a function of reactiontime with R. damascena extracts (30 mL HAuCl4 1103 M with 15 mLR. damascena extract). (b) UVvis absorption spectrum of AgNPs recorded as a

function of reaction time with R. damascena extracts (30 mL AgNO3 1102 M

with 10 mL R. damascena extract).

range of 510550 nm and 400450 nm in an aqueous medium,respectively. UVvis spectra of these aliquots were monitored asa function of time of reaction (Fig. 4a and b). These biosynthe-sized AuNPs and AgNPs were laid aside at room temperature3 months later. There is no obvious aggregation in the solution,and its absorption value shows only a little reduction. Theresults from Fig. 4a and b suggest that the AuNPs and AgNPssynthesized by R. damascena have very good stability.

3.2. TEM analysis of nanoparticles

The particle size can be determined theoretically using techni-ques like UVvis spectroscopy, XRD and experimentally usingmicroscopic techniques like TEM. The morphology of the synthe-sized AuNPs and AgNPs was also determined by TEM images.AuNPs and AgNPs to be conned within a supporting matrix, likelycomprised biomolecules acting as a capping agent or stabilizerduring synthesis, and thus controlling nanoparticle growth and

clustering. Alternatively, it is possible that the biomolecules pre-sent in the R. damascena extract were believed to be the agentsresponsible for reducing the Au3 and Ag to Au1 and Ag1. TEMimages of the AuNPs and AgNPs obtained under normal conditionsdemonstrate that nanoparticles were self-assembled, with averagesizes ranging from 10 to 30 nm, as shown in Fig. 5. Fig. 5(ad)shows typical TEM micrographs of AuNPs and AgNPs synthesizedafter reduction of HAuCl4 and AgNO3 with R. damascena extract.Interpretation of TEM images of AuNPs at 15 and 10 mL and AgNPsat 10 and 5 mL of R. damascena suggests an increase in particle sizewith a decrease in extract quantity. As the amount of R. damascenaextract in the reaction medium is increased, the average edgelengths of the AuNPs and AgNPs decrease. From the above discus-sions, for the formation of AuNPs and AgNPs, synthesized invarious ratios of HAuCl4 and AgNO3 with R. damascena extract, itcan be said that the size of these nanoparticles are highly affectedby the ratio of HAuCl4 and AgNO3 versus R. damascena extract.The rate of formation of AuNPs and AgNPs was found to be slower

10

S.M. Ghoreishi et al. / Physica E 44 (2011) 97104100Fig. 5. TEM micrographs of AuNPs and AgNPs synthesized at (a) 30 mL HAuCl4 1

R. damascena extract, (c) 30 mL AgNO3 1102 M with 10 mL R. damascena extract an3 M with 15 mL R. damascena extract, (b) 30 mL HAuCl4 1103 M with 10 mL

d (d) 30 mL AgNO3 1102 M with 5 mL R. damascena extract.

According to the equation [34]

L klbcosy

1

where L is the particle size (nm), k is the Scherrer constant, b isthe full width half maximum, y is half of Bragg angle and l is thewavelength of X-ray [35]. Fig. 7a and b shows a representativeXRD pattern of the AuNPs and AgNPs synthesized by theR. damascena compound after completion of the reduction.

3.4. FT-IR studies

Typical FT-IR absorption spectra of R. damascena extract beforeand after bioreduction are shown in Fig. 8. FT-IR spectra werecarried out to identify the potential biomolecules R. damascenaresponsible for the reduction and capping of the bioreduced AuNPs

S.M. Ghoreishi et al. / Physica E 44 (2011) 97104 1015

10

15

20

25

Dist

ribut

ion

perc

enta

ge (%

)at the lowest concentration and hence absorbance is also weaker.The obtained histogram using the enlarged TEM graphs revealedthat almost 32% of the AuNPs were 16 nm and 23% of the AgNPswere 21 nm in diameter (Fig. 6a and b). In AuNPs and AgNPs theparticles are almost quasi-spherical with mean size of 15.3 nm and18.3 nm, respectively.

3.3. XRD analysis of nanoparticles

The crystalline nature of AuNPs and AgNPs was furtherconrmed from X-ray diffraction (XRD) analysis. This was com-pared to the particle sizes determined by TEM images. For XRDthe particles were calculated using the DebyeScherrer equation.The average crystallite size according to DebyeScherrer equationcalculated using the width of the (1 1 1) peak is found to be 14 nmfor AuNPs and 19 nm for AgNPs nearly in agreement with theparticle size obtained from the TEM image of AuNPs and AgNPs.

and AgNPs. A number of broad bands are observed in the region9003500 cm1 centered at 3440, 1740, 1620 and 1370 cm1.R. damascena have been reported to consist of avanoids andpolyphenols which form the major component [22,23]. The IR bandsobserved at 1370 and 1740 in R. damascena extract are characteristicof the CO and CQO stretching modes of the carbonyl functionalgroup in ketones, aldehydes and carboxylic acids. The peak at1620 cm1 can be assigned to the vibrational modes of CQCdouble bonds of these molecules. The proposed oxidized structureof avanoids, gallic acid and myricetin are shown in Fig. 9. Thecarbonyl groups from the avanoid and polyphenolic compoundhave a stronger ability to bind Au and Ag ion, so that the avanoid

0

5

10

15

20

25

30

35

8

Dist

ribut

ion

perc

enta

ge (%

)

Particle Diameter (nm)

09

Particle Diameter (nm)10 11 12 13 14 15 16 17 18 19 20 21 22

9 10 11 12 13 14 15 16 17 18 19

Fig. 6. (a) Histogram of the size distribution of AuNPs synthesized by treating15 mL R. damascena extract with 30 mL HAuCl4 1103 M solution.(b) Histogram of the size distribution of AgNPs synthesized by treating 10 mL

R. damascena extract with 30 mL AgNO3 1102 M solution.Fig. 7. (a) XRD patterns of AuNPs synthesized by treating 30 mL HAuCl41103 M with 15 mL R. damascena extract. (b) XRD patterns of AgNPs synthe-

sized by treating 30 mL AgNO3 1102 M with 10 mL R. damascena extract.

and polyphenolic compound could form a coat over the metalnanoparticle to prevent gathering of particles. The linkages betweencarbonyl groups and metal ion give a well-known signature in theFT-IR spectrum. After the bioreduction of R. damascena extract withAu3 and Ag , the shift in the peak at 1740 cm1 is attributed tothe binding of carbonyl group with nanoparticles. Also, the hydroxylpeak at 3440 cm1 decreases in the presence of nanoparticles,which indicates Au3 and Ag ions are reduced with the hydroxyl

groups of the avanoid and polyphenol and the hydroxyl groups areoxidized to carbonyl groups.

3.5. Assembling of AuNPs modied glassy carbon electrode

Electrocatalytic activity of biosynthesized AuNPs was mea-sured by cyclic voltammetry (CV). Fig. 10 shows the CV responsesof 5.0103 M [Fe(CN)6]3/4 in a 0.1 M KCl solution at thebare-GCE and AuNPs assembled electrodes. The electron transferkinetics of a redox couple in the solution on the AuNPs assembledelectrodes depend on the surface of the GCE. As can be seen,Fe(CN)6

3/4 shows a couple of well-dened redox waves at bare-GCE electrode (Fig. 10, curve c) with a peak-to-peak separation of190 mV at 45 mV s1 scan rate. After the self-assembly of AuNPs,an obvious increase in redox peak currents and decrease in peak-to-peak separation are observed (Fig. 10, curve d). An increase incurrent responses and decrease in DEp on the AuNPs assembledGCE electrodes were attributed to rapid electron transfer rate onthe GCE surface. On the other hand, the self-assembled AuNPswere successfully assembled on the GCE electrode and acted asthe inert electron and mass transfer blocking layer. The typicalcyclic voltammograms of the AuNPs assemble GCE in 0.1 M KClsolution that contains 5.0103 M [Fe(CN)6]3/4 with scanrates of 25, 45, 65, 85, 105, 125 and 145 mV s1 as shown inFig. 11. As can be observed, the oxidation peak potential shiftedwith increasing the scan rates toward a more positive potential,conrming the kinetic limitation of the electrochemical reaction.In the range of 25145 mV s1, the anodic peak current (Ipa) of5.0103 M [Fe(CN)6]3/4 increased linearly with an increasein the square-root of the scan rate (u1/2). This result indicated thatthe oxidation was controlled by diffusion (Fig. 11b). According to

HO

O

OH

R

OH

OH

O

OH

O

O

OH

OH

OH

OH O

OH

OH

O

400Wavenumber (cm-1)

(a)

(c)

(b)

900 1400 1900 2400 2900 3400 3900

Fig. 8. FT-IR spectra of (a) dried R. damascena extract; dried powder of (b) AuNPsand (c) AgNPs.

S.M. Ghoreishi et al. / Physica E 44 (2011) 97104102OHO

OHOHOH OHFig. 9. Mechanism of oxidation of avO

OO

O

R

H

OH O

O

O

O

OH

H

OH O

O

O

OH

2e-++ 2H+

2e-++ 2H+

2e-++ 2H+anoids, myricetin and gallic acid.

S.M. Ghoreishi et al. / Physica E 44 (2011) 97104 103-60

-40

-20

0

20

40

60

-0.4

I /

A b

c

d

a

-0.2 0 0.2 0.4 0.6 0.8 1RandlesSevcik equation [36]

Ip 2:69 105n3=2AD1=2Cu1=2 2where n is the number of electrons transferred in the reaction, u isthe scan rate, A is the surface of the electrode, C is the concentra-tion of reactant and Ip is the peak current of the reactant. Linearregression equations were as follows:

IpamA 0:1363u1=2 mVs11=222:501, R2 0:991An approximate estimate of the surface coverage of the

electrode was made by adopting the method used by Sharp[37]. According to this method, the peak current is related tothe surface concentration of mediator, ! , by the followingequation:

Ip n2F2A!n=4RT 3where n represents the number of electrons involved in thereaction, A is the surface area (0.0314 cm2) of the GCE, !(mol cm2) is the surface coverage of mediator and other symbolshave their usual meanings. From the slope of anodic peak currents

Met. Chem. 35 (2005) 19.[10] B. Ankamwar, C. DamLe, A. Ahmad, M. Sastry, J. Nanosci. Nanotechnol.

Food Res. Technol. 219 (2004) 416.

E / V vs Ag/AgCl

Fig. 10. Cyclic voltammograms at 50 mV s1 for the bare-GCE electrode in theabsence (curve a) and presence (curve c) of 5.0103 M [Fe(CN)6]3/4 in a 0.1 MKCl solution; the AuNPs assembled GCE in the absence (curve b) and presence

(curve d) of 5.0103 M [Fe(CN)6]3/4 in a 0.1 M KCl solution.

-50-40-30-20-10

0102030405060

-0.6 -0.2 0.2 0.6 1.0 1.4 1.8E / V vs Ag/AgCl

I /

A

Fig. 11. Cyclic voltammograms of AuNPs assembled GCE in 5.0103 M[Fe(CN)6]

3/4 in a 0.1 M KCl with scan rates of 25, 45, 65, 85, 105, 125 and145 mV s1. (a) Plot of peak current versus scan rate, (v/mV s1). (b) Plot of peakcurrent versus the square-root of scan rate, (v/mV s1)1/2.[28] G. Block, Nutr. Rev. 50 (1992) 207.[29] G. Block, L. Langseth, Food Technol. 48 (1994) 80.[30] H. Avicenna, Canon of Medicine, in: A. Sharafkandi (Trans.), Soroosh Press,

Tehran, 1988, pp. 9698.5 (2005) 1665.[11] A.K. Singh, M. Talat, D.P. Singh, O.N. Srivastava, J. Nanopart. Res. 12 (2010)

1667.[12] R. Deshpande, M.D. Bedre, S. Basavaraja, B. Sawle, S.Y. Manjunath,

A. Venkataraman, Colloids Surf. B 79 (2010) 235.[13] R.G. Haverkamp, A.T. Marshall, D. Agterveld, J. Nanopart. Res. 9 (2007) 697.[14] D. Philip, Physica E 42 (2010) 1417.[15] D. Philip, C. Unni, S. Aswathy Aromal, V.K. Vidhu, Spectrochim. Acta A, Mol.

Biomol. Spectrosc. 78 (2011) 899.[16] D. Philip, Spectrochim. Acta A, Mol. Biomol. Spectrosc. 78 (2011) 327.[17] D. Philip, C. Unni, Physica E 43 (2011) 1318.[18] S.P. Dubey, M. Lahtinen, M. Sillanp, Colloids Surf. A 364 (2010) 34.[19] S.P. Dubey, M. Lahtinen, M. Sillanp, Process Biochem. 45 (2010) 1065.[20] S. Gudin, Plant Breed. Rev. 17 (2000) 159.[21] E. Kovats, J. Chromatogr. 406 (1987) 185.[22] N. Kumar, P. Bhandari, B. Singh, A.P. Gupta, V.K. Kaul, J. Sep. Sci. 31 (2008)

262.[23] P. Bhandari, N. Kumar, A.P. Gupta, B. Singh, V.K. Kaul, J. Sep. Sci. 30 (2007)

2092.[24] F. Shahidi, M. Naczk, Food Phenolics: Sources, Chemistry, Effects, Applica-

tions, Technomic Publishing Company, Inc., Lancaster, PA, 1995.[25] U. Undeger, S. Aydn, A.A. Bas-aran, N. Bas-aran, Toxicol. Lett. 151 (2004) 143.[26] G. Teresita, R.A. Ester, J.A. Osvaldo, P.L. Eugenia, II Farmaco 56 (2001) 683.[27] A. Ferancova, L. Heilerova, E. Korgova, S. Silhar, I. Stepanek, J. Labuda, Eur.versus scan rate (Fig. 11a) the surface coverage of AuNPs/GCE is5.3106 mol cm2 for n1.

4. Conclusion

The spanking new and simple method for biosynthesis ofAuNPs and AgNPs by R. damascena extract offers a valuablecontribution in the area of green synthesis and nanotechnologywithout adding different physical and chemical steps. The synth-esis of AuNPs and AgNPs by R. damascena extracts indicated thatavanoids and polyphenols compounds could be one of the keybiomolecules serving multiple roles. The nanoparticles werecharacterized by UVvis, TEM, XRD and FT-IR measurements.This synthetic green method obtained stable aqueous solutions ofAuNPs and AgNPs. This simple, low cost, non-toxic and eco-friendly method for development of AuNPs and AgNPs may bevaluable in environmental, biotechnological, pharmaceutical andmedical applications. Moreover, this system could also be used inelectrochemical applications. The biosynthesized AuNPs areassembled to the surface of the GCE and could raise electronictransmission rate between the electrode and [Fe(CN)6]

3/4.

Acknowledgments

The authors wish to express their gratitude to the University ofKashan for supporting this work.

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S.M. Ghoreishi et al. / Physica E 44 (2011) 97104104

Green synthesis of silver and gold nanoparticles using Rosa damascena and its primary application in electrochemistryIntroductionExperimentalMaterialsApparatusSynthesis of AuNPs and AgNPsAssembling of AuNPs modified glassy carbon electrode

Results and discussionUV-vis absorbance spectroscopyTEM analysis of nanoparticlesXRD analysis of nanoparticlesFT-IR studiesAssembling of AuNPs modified glassy carbon electrode

ConclusionAcknowledgmentsReferences