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Industrial Crops and Products 52 (2014) 745– 751

Contents lists available at ScienceDirect

Industrial Crops and Products

journa l h om epage: www.elsev ier .com/ locate / indcrop

hyto-synthesis of gold nanoparticles using fruit extract of Hoveniaulcis and their biological activities

agaraj Basavegowda, Akber Idhayadhulla, Yong Rok Lee ∗

chool of Chemical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea

r t i c l e i n f o

rticle history:eceived 31 August 2013eceived in revised form7 November 2013ccepted 2 December 2013

eywords:

a b s t r a c t

The authors describe the synthesis of gold nanoparticles (GNPs) at room temperature using an aqueousextract of Hovenia dulcis fruit and the antioxidant and antibacterial activities of the GNPs obtained. Thedevised method provides a simple, cost-effective aqueous means of producing spherical and hexagonalGNPs of size ∼20 nm. The synthesized GNPs were characterized by UV–vis spectrum and obtain a peak at536 nm. Fourier transform infrared (FT-IR) spectroscopy results showed that the extract containing somebiomolecules accountable for both reducing as well as capping gold ions into GNPs. Transmission electron

ovenia dulcisold nanoparticlesntioxidantiomoleculesapping agent

microscopic (TEM) studies of the particles revealed a dominance of spherical particles with a very fewhexagonal GNPs. The face centered cubic structure of the GNPs was confirmed by X-ray diffraction (XRD)peaks at 38◦, 44◦, 64◦ and 77◦, which were indexed to the (1 1 1), (2 0 0), (2 2 0), and (3 1 1) planes withclear circular spots in the selected area electron diffraction (SAED). Elemental analysis was performedby energy dispersive X-ray analysis (EDX). In addition, the authors investigated in vitro antioxidant and

f the

antibacterial properties o

. Introduction

The fabrication of metal nanoparticles has drawn considerablettention in the field of nanotechnology. Due to their vast range ofpplications, the synthesis of gold nanoparticles (GNPs) of differenthapes and sizes is of great interest. Many methodologies have beensed to date, including physical, chemical, and biological processes.owever, most are not ecofriendly due to high capital costs and these of toxic chemicals. Accordingly, simple and greener proceduresor the synthesis of gold nanoparticles are of interest (Inbathamizht al., 2013). The biosyntheses of GNPs using plant parts, such as,eaves (Song et al., 2009), flowers (Nagaraj et al., 2011; Nagajyothit al., 2012), fruits (Nagaraj et al., 2013; Tai et al., 2011; Ghodaket al., 2010; Ankamwar et al., 2005), fruit peel (Ahmad et al., 2012;ankar et al., 2010; Nagaraj and Lee, 2013), and seeds (Sharma et al.,007), have been reported. Fruit mediated synthesis of GNPs is aew and exciting area of research with considerable potential forhe development of processes to produce differently shaped andized nanoparticles.

The use of microorganisms such as Megatherium sp. (Li et al.,009), Fusarium semitactum (Basavaraja et al., 2008; Balaji et al.,

008), Rhodopseudomonas sp. (He et al., 2007), Cladosporium sp.Balaji et al., 2009) and Fusarium oxysporum (Ahmad et al., 2003)or the production of metal nanoparticles is relatively new and

∗ Corresponding author. Tel.: +82 53 810 2529; fax: +82 53 810 4631.E-mail address: yrlee@yu.ac.kr (Y.R. Lee).

926-6690/$ – see front matter © 2013 Elsevier B.V. All rights reserved.ttp://dx.doi.org/10.1016/j.indcrop.2013.12.006

biosynthesized GNPs, which were found to be significant.© 2013 Elsevier B.V. All rights reserved.

exciting, but it is more beneficial to use plants or plant extractsthan microorganisms, as they eliminates elaborate process for cellculture maintaining and also time consumption (Jae and Beom,2009). In addition, the syntheses of metal nanoparticles using cowmilk (Lee et al., 2013) and honey (Philip, 2009) have also beenreported. The reduction of Au3+ using plant extracts is more advan-tageous than using chemicals. Biologically synthesized GNPs havevast applications in the biosensing (Lim et al., 2009), catalytic(Dauthal and Mukhopadhyay, 2012), drug delivery (Brown et al.,2010), therapeutic (Mukherjee et al., 2007), and diagnostic (Huanget al., 2009) fields.

H. dulcis, which is also known as oriental raisin tree, belongsto the family Rhamnaceae and it has long been used in Chineseherbal medicine for the treatment of hangover symptoms. It islisted in the Tang Materia Medica, which dates back to 659 A.D.Dihydromyricetin, a flavonoid isolated from H. dulcis (Shen et al.,2012) has well-known anti-alcohol intoxication effects, and hasbeen used in traditional folk remedies for the treatment of liver dis-eases (Hase et al., 1997), and alcoholic detoxification (Kim, 2001).Furthermore, it has been reported to reduce alcohol concentrationin blood remarkably (Chen et al., 2006). In an effort to develop envi-ronmentally benign methods, the investigation is focused for thefirst time to outline the use of H. dulcis fruit extract as capable ofreducing and capping agents for the synthesis of GNPs.

Herein, we describe an environmental-friendly method for syn-thesizing and stabilizing GNPs based on the reduction of aqueousAuCl4− ions by using biologically active H. dulcis fruit extract. Inaddition, as a biological application of this work, the evaluation for

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ntioxidant and antibacterial activities of synthesized GNPs with H.ulcis extract is also reported. The synthesized GNPs were charac-erized by UV–vis spectroscopy, Fourier transform infrared (FT-IR)pectroscopy, transmission electron microscopy (TEM), and by X-ay diffraction (XRD).

. Materials and methods

.1. Microorganism and chemicals

All chemicals were purchased from Sigma–Aldrich. All glass-ares were washed with sterile water and dried in an oven beforese. Dried fruits of H. dulcis were purchased at Yeongchon, Southorea. The standard bacterial strains E. coli (KCTC-1924) and S.ureus (KCTC-1916) were obtained from Korean Collection of Typeulture (KCTC).

.2. Aqueous fruit extract Preparation

The dried fruits of H. dulcis were collected and grind to makene powder. The fruit broth solution was prepared by taking 5 g ofnely powdered fruit bodies in Erlenmeyer flask along with 200 mL25 mg/mL concentration) of millipore water and then boiling the

ixture at 80 ◦C for 5 min before finally decanting it. The extractbtained was filtered through a Whatman filter paper and it wasollected in a 250 mL Erlenmeyer flask. The solutions were storedt 4 ◦C for further use.

.3. Green synthesis of GNPs using fruit extract

To synthesize GNPs, 5 mL of H. dulcis fruit extract was mixedith 50 mL of an aqueous solution of 1 mM chloroauric acid

HAuCl4) and stirred for 10 min at room temperature. Reductionccurred rapidly as indicated by a reddish brown color after 30 min,ndicating the formation of GNPs. The GNPs obtained were puri-ed using a Beckman Coulter’s Avanti J–E centrifuge (USA) at0,000 rpm for 30 min.

.4. UV–vis spectroscopy

The reduction of Au ions in solution was monitored by measur-ng the UV–vis spectra of the solution (1 mL of GNPs solution + 3 mLf distilled water) against distilled water as a blank using an Optizen220 (Double beam) UV–vis spectrophotometer in quartz cuvettest a resolution of 1 nm between 450 and 650 nm.

.5. FT-IR spectroscopy

FT-IR analysis was carried out by JASCO FT-IR spectrophotome-er in the range of 4000–400 cm−1. The sample was dried andrinded with KBr pellets and analyzed. The various modes of vibra-ions were identified to determine the different functional groupsresent in GNPs.

.6. Thermogravimetric analysis (TGA)

TGA analysis was performed on a SDT Q600 V20.5 Build 15.amples (10 mg) were placed in platinum sample pans and heatednder an argon atmosphere at a rate of 20–1000 ◦C.

.7. TEM and EDX of GNPs

The size and shape of the GNPs were measured with transmis-ion electron microscopy (TEM) using FEI Tecnai G2 F20 ST FE-TEM.amples were prepared by ultrasonically dissolving GNPs in dou-le distilled water. A drop of this solution was then deposited onto

and Products 52 (2014) 745– 751

a carbon coated Cu grid and allowed to evaporate under ambientconditions. The microscope was also equipped with a Genesis liquidnitrogen cooled energy-dispersive X-ray analysis (EDX) detector fordetailed elemental analysis.

2.8. XRD analysis

A few grams of synthesized GNPs grounded by mortar and pes-tle to make fine powder and smear uniformly onto a glass slide,assuring a flat upper surface to achieve a random distribution. TheXRD studies were performed with PANalytical X’Pert MRD model at30 kV, 40 mA, with Cu K� radians at 2� angle. The particle sizes andnature of GNPs were determined to identify crystalline structuresand determine unit cell dimensions.

2.9. In vitro antioxidant activity

2.9.1. DPPH radical scavenging activityMethanolic solutions of DPPH exhibit a strong purple color,

with strong absorption at 517 nm, and when reduced are a yel-low color. Therefore, there is an inverse relationship between theremaining DPPH concentration and the anti-radical activity of anantioxidant (Cefarelli et al., 2006). Accordingly, synthesized GNPswere examined for their ability to prevent the bleaching of thepurple colored methanol solution of 1,1-diphenyl-1-picrylhydrazyl(DPPH). Aliquots (1.6 mL) of various concentrations of GNPs (100,200, 400, and 500 �g/mL) in methanol were added to 1.6 mL of0.004% (w/v) methanol solution of DPPH. After 30 min at room tem-perature, absorbance was read against a blank at 517 nm using anOptizen 3220 (Double beam) UV–vis spectrophotometer. Percent-age inhibition of DPPH oxidation was calculated using the followingequation.

DPPH scavenging effect(%) =(

Acontrol − Asample

Acontrol

)× 100

where Acontrol is the absorbance of the DPPH solution and Asample isthe absorbance of the test sample.

2.9.2. Hydrogen peroxide (H2O2) scavenging activityH2O2 scavenging power was determined as previously

described by Ruch et al. (1989). A solution of H2O2 (40 mM) wasprepared in phosphate buffer (pH 7.4). 100, 200, 400, or 500 �g/mLconcentrations of the GNPs in 3.4 mL phosphate buffer were addedto H2O2 solution (0.6 mL, 40 mM). Absorbance of reaction mixtureswas recorded at 230 nm. Percentage inhibition of H2O2 scavengingwas calculated using the following equation.

% Inhibition =(

Acontrol − Asample

Acontrol

)× 100

where Acontrol is the absorbance of the control reaction (contain-ing all reagents except the test compound), and Asample is theabsorbance of the sample.

2.9.3. Nitric oxide (NO) scavenging activityNitric oxide scavenging activity was measured using a slightly

modified version of the method devised by Marcocci and co-workers (Marcocci et al., 1994). Sodium nitroprusside (1 mL,10 mM) and 1.5 mL of phosphate buffer saline (0.2 M, pH 7.4) wereadded to different concentrations (100, 200, 400 or 500 �g/mL) of

GNPs and incubated for 150 min at 25 ◦C. Aliquots (1 mL) of reac-tion mixtures were then treated with 1 mL of Griess reagent (1%sulfanilamide, 2% H3PO4 and 0.1% naphthyl ethylenediamine dihy-drochloride). The absorbance of the chromatophore was measured

Crops and Products 52 (2014) 745– 751 747

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%

wia

2

(bpFtbcfdF

2

mtC3tcpwz

3

fiw3fim

fmewa(v(dtati

rqliaet

Fig. 1. UV–vis spectra of GNPs synthesized from H. dulcis fruit extracts. Inset diagram

son with that of crude extracts showed the progress of reduction ofGNPs. After reduction, the oxidized biomolecules were capped onthe GNPs and showed their peaks in IR spectrum.

A= flavonolsB= other bioactive materials

A + Bn

Au+3 nA + B

Au+mn

seed particle s

oxidizedmaterials

nAuo

n

o

Au+3 n

N. Basavegowda et al. / Industrial

t 546 nm. Nitric oxide scavenging activity was calculated using theollowing equation.

No scavenging =(

Acontrol − Asample

Acontrol

)× 100

here Acontrol is the absorbance of the control reaction (contain-ng all reagents except the test compound), and Asample is thebsorbance of the sample.

.9.4. Ferric reducing antioxidant power (FRAP) assayFRAP assays were conducted as described by Benzie and Strain

Benzie and Strain, 1996) with minor modification. The method isased on the reduction of a ferric 2,4,6-tripyridyl-s-triazine com-lex (Fe3+-TPTZ) by antioxidants to the ferrous form (Fe2+-TPTZ).RAP reagent was prepared freshly by mixing 2.5 mL of TPTZ solu-ion (10 mM in 40 mM HCl) and FeCl3 (20 mM) in 25 mL of acetateuffer (300 mM and pH 3.6). The light blue Fe3+-TPTZ reagenthanges to dark blue after contact with an antioxidant, due to theormation of Fe2+-TPTZ. Absorbance was monitored at 593 nm forifferent concentrations (100, 200, 400 or 500 �g/mL) of GNPs inRAP reagent (Dehghan and Khoshkam, 2012).

.10. In vitro antibacterial activity

Antibacterial assays were performed using a disc diffusionethod (Cormican et al., 1996; Bauer et al., 1996). The antibac-

erial potential of GNPs was tested against E. coli and S. aureus.ultures of the bacterial strains were prepared in Luria broth at0 ◦C for 24 h. Ciprofloxacin was used as a standard. Sterile fil-er paper discs (5 mm diameter) were moistened with GNPs andiprofloxacin (100 �g/disc) on agar culture plates that had beenreviously inoculated separately with the microorganisms. Platesere incubated at 37 ◦C, and the diameters of growth inhibition

ones were measured after 24 h.

. Results and discussion

The fruit extract of H. dulcis (25 mg/mL concentration) wasrst mixed with HAuCl4 solution. Then, the pale brown color ofater extracts changed to reddish brown color immediately within

0 min, indicating the formation of GNPs. The color change con-rmed that molecules present in the fruit extracts reduced the goldetal ions into GNPs.UV–vis spectroscopy is an efficient technique to determine the

ormation and stability of GNPs. The color change of the reactionixture from pale yellow to dark violet after the addition of fruit

xtracts to 1 mM aqueous HAuCl4 resulted the formation of GNPs. Itas observed that the gold surface plasmon resonance (SPR) band

ppeared at 530 nm (Fig. 1). The SPR band increased in intensitypink curve) when the reaction time increases with time inter-als from 30 min to 24 h without any shift in the peak wavelengthMulvaney, 1996). The intensity of the surface plasmon peak isirectly proportional to the density of the nanoparticles in solu-ion (Ahmad et al., 2013) and the maximum intensity is accomplishfter 24 h of the reaction which confirms the complete reduction ofhe AuCl4− ions. The inset images in Fig. 1 shows the color changesndicating the formation of GNPs at different time intervals.

Very recently, three flavonol derivatives, quercetin 3-O-�-l-hamnopyranoside, kaempferol 3-O-�-l-rhamnopyranoside, anduercetin 3-O-�-d-glucopyranoside as major compounds were iso-

ated from the hot water extracts of H. dulcis, which was distributed

n Korea (Cho et al., 2013). These kinds of flavonol derivativesre known to act as potential reducing agents by donating of freelectrons (Kasthuri et al., 2009). FT-IR spectrum of the crude mix-ures obtained from water extracts of H. dulcis showed absorptions

(A) shows reduction after 30 min, (B) after 1 h, (C) after 6 h, (D) after 12 h, and (E)after 24 h.

at 3422 (OH), 2933 (C H), 1650 (C O), 1617 (C C), 1581, 1496,1452, 1396, 1362, 1258, 1169, 1060 cm−1 (Fig. 2). Importantly,by comparison with reported IR data, the crude mixtures showcharacteristic absorption bands for flavonol derivatives (Shan andO’Doherty, 2006).

The peak at 3422 cm−1 is the stretching vibration for OH ofphenol groups on the flavonol rings. The two bands of 1650 and1617 cm−1 may be attributed to the stretching vibration of C Oand C C on chromen-4-one rings of flavonol derivatives. The peaksat 1581, 1496, and 1452 cm−1 may be from C C of aromatic ring.The peaks of 1396 and 1362 cm−1 may be attributed to vibra-tions of C O H bending, whereas that at 1258 cm−1 may be fromC O stretching of phenols. The peaks 1169 and 1060 cm−1 may beassigned to the stretching vibrations of C O of 1◦ and 2◦ alcohols.

The mechanism for the formation of nanoparticles can beexplained as shown in Scheme 1. The related mechanism of reduc-tion of gold salts (Au3+) to gold nanoparticles (Au0) using bioactivephyto-molecules has been already reported (Babu et al., 2013). Onthe basis of this mechanism, the hydroxyl and carbonyl groups offlavonol derivatives and other bioactive molecules in water extractsfirst bind with gold ions (Au3+) to form gold complexes, which arereduced to seed particles (Au0). The reduced seed particles undergoagglomeration and form the clusters, which act as nucleation cen-ters and catalyze the reduction of remaining metal ions.

The spectrum of synthesized GNPs (Fig. 3) revealed absorptionbands at 3372, 2924, 1620, 1399, and 1050 cm−1. The absence of aC O group and shift of a C C stretching to 1620 cm−1 by compari-

gold nanoparticles

Aun clusterss

Scheme 1. Possible mechanism for synthesis of gold nanoparticles.

748 N. Basavegowda et al. / Industrial Crops and Products 52 (2014) 745– 751

Fig. 2. FT-IR spectrum of H

Gcc

F

Fig. 3. FT-IR spectrum of GNPs synthesized from H. dulcis fruit extracts.

TGA spectrum of GNPs showed the significant weight loss ofNPs when heated from 20 ◦C to 1000 ◦C (Fig. 4). This result indi-ated that bioactive molecules were capped on the GNPs and wereompletely degraded under high temperature.

ig. 4. Thermogravimetric analysis of GNPs synthesized from H. dulcis fruit extracts.

. dulcis fruit extracts.

The size and morphology of the synthesized GNPs were deter-mined by transmission electron microscopy (TEM) images. A dropof gold nanoparticle solution was placed on to a carbon coated Cugrid and the sample was allowed to dry. The TEM images wererecorded at different magnification to find the individual parti-cles. Fig. 5a shows polydisperse GNPs with different shapes such asspherical and hexagonal prepared using the fruit extract of H. dulcisas reducing agent and the scale bar corresponds to 50 nm. Fig. 5bshows the poly dispersed spherical shape nanoparticles correspondto 10 nm. The particles were formed in different sizes, ranging from15 nm to 20 nm in diameter. Average particle size as obtained fromTEM analysis was found to be 20 nm. Inspection of TEM imagesclearly indicated that a faint thin layer of other material was visu-alized on the surface of GNPs which might be due to the cappingorganic materials of fruit extracts. The synthesized GNPs showedvariable shapes, and most of them were spherical and a few hexag-onal shapes. The selected area electron diffraction (SAED) patternsshown in Fig. 5c represent the five bright circular rings correspond-ing to (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) reflections of facecentered cubic crystalline gold. The capping material is believed tobe a bioorganic component of H. dulcis. Fig. 5d shows a representa-tive EDX spectrum of the GNPs. Appearance of a strong absorptionpeak approximately at 3 keV representing the composition of goldphase. The peaks for copper and carbon were also found, but thoseoriginated from the carbon-coated copper grid used for TEM samplepreparation and EDX analysis (He et al., 2008).

X-ray diffraction was used to confirm the crystalline nature ofthe particles. Fig. 6 shows a representative XRD pattern of the goldnanoparticles synthesized by H. dulcis fruit extracts after the com-plete reduction of Au3+ to Au0. XRD analysis showed three distinctdiffraction high peaks at 38.18◦, 44.38◦ and 64.57◦, 77.56◦ whichindexed the planes (1 1 1), (2 0 0), (2 2 0) and (3 1 1) of the cubicface cantered gold followed by a low peak at 81.72◦ indexed as(2 2 2) planes. The cubic face-centered structures of gold matchedwith the database of Joint Committee on Powder Diffraction Stan-dards (JCPDS No. 00-004-0784), revealing that the synthesizedgold nanoparticles are composed of pure crystalline gold. The ratio(0.32) between the (2 0 0) and (1 1 1) diffraction peaks is lowerthan the conventional bulk intensity ratio (0.52), suggesting that

the (1 1 1) plane is the predominant orientation supporting theresult obtained from high-resolution TEM measurement (Philip,2010). Similar results were reported earlier for gold nanoparticles(Inbakandan et al., 2010; Bankar et al., 2010).

N. Basavegowda et al. / Industrial Crops and Products 52 (2014) 745– 751 749

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ig. 5. TEM micrograph of GNPs at different magnifications: (a) the scale bar correesult illustrating the formation of GNPs.

A variety of effective gold nanoparticle-based methods for eval-ation of antioxidant activities were described, which includehenolic acids (Scampicchio et al., 2006), epigallocatechin gallateLeu et al., 2012), glutathione (Pongsuchart et al., 2012), curcuminSingh et al., 2013), chitosan-stabilized growth of GNPs (Duy et al.,013). The reported GNPs-based evalution for antioxidant activi-ies has been mainly used pure organic chemicals and materialss stabilizers or reducing agents. Despite their own merits, theirotential use in biomedical field is uncertain owing to their toxichemicals and nature. Therefore, more environmentally benign and

reen methods with water extracts of bioactive plants are neededmproving on these shortcomings.

Fig. 6. XRD Patterns of GNPs synthesized from H. dulcis fruit extracts.

ds to 50 nm, (b) the scale bar corresponds to 10 nm, (c) SAED pattern and (d) EDX

Therefore, the synthesized GNPs from fruit extracts of H. dul-cis were tested for the antioxidant properties using the abovedescribed 1,1-diphenylpicrylhydrazyl (DPPH), hydrogen peroxide(H2O2), nitric oxide (NO), and Ferric reducing antioxidant power(FRAP) methods and all assays were performed at four differentconcentrations (100, 200, 400 and 500 �g/mL) as shown in Table 1.

DPPH was first used as a preliminary radical scavenging activitytest. The free radical scavenging activity of GNPs for DPPH radicalwas found to increase with concentration, and to peak at 59.17% at500 �g/mL. As shown in Table 1, the hydrogen peroxide scavengingactivity of GNPs increased with increasing concentration, but theactivitiy of GNPs was lower (48.60%) than standard ascorbic acid(83.22%) at 100 �g/mL.

The nitric oxide (NO•) radical reacts with Griess reagent, to formformazan, which can be measured spectrophotometrically. TheNO• radical is unstable and highly electronegative, and thus, easilyaccepts an electron from GNPs. In this case, GNPs showed highlyresponse (88.75%) at 500 �g/mL as compared with standard ascor-bic acid (83.43%) at 100 �g/mL and percent inhibition increasedwith the increase of GNPs concentration.

As mentioned above, the FRAP assay measures the ability ofan antioxidant to reduce ferric 2,4,6-tripyridyl-s-triazine complex[Fe3+-(TPTZ)2]3+ in acidic medium. FRAP values are calculated bymeasuring absorbance increase at 593 nm and relating these to aferrous ion or to an antioxidant standard solution, such as, ascor-bic acid. The potent reducing power was observed for ascorbic acid(0.705) at 100 �g/mL. GNPs had relatively low reducing abilities at

100–500 �g/mL by comparison with a standard sample.

As shown in Fig. 7, our results demonstrated that antioxidantactivities increased with the increase of concentrations of syn-thesized GNPs. In addition, the GNPs showed more significant

750 N. Basavegowda et al. / Industrial Crops and Products 52 (2014) 745– 751

Table 1In vitro antioxidant activities of synthesized GNPs.

Compound Concentration (�g/mL)a Percentage of inhibition (%) radical scavenging activity Fe3+–Fe2+ reducing ability b

DPPH assay H2O2 assay NO assay (FRAP) assay

GNPs 100 48.70 ± 0.08 15.91 ± 0.30 55.38 ± 0.24 0.367 ± 0.31200 53.79 ± 0.21 25.59 ± 0.69 65.19 ± 0.31 0.369 ± 0.33400 56.60 ± 0.36 41.72 ± 0.17 87.79 ± 0.11 0.370 ± 0.05500 59.17 ± 0.14 48.60 ± 0.65 88.75 ± 0.09 0.379 ± 0.18

Ascorbic acid 100 98.17 ± 0.13

a Value were the means of three replicates ± SD.b Values are expressed as absorbances, and high absorbance indicates high reducing po

Fig. 7. Summarized antioxidant activities of GNPs.

Table 2The antibacterial activities of synthesized GNPs.

Compounds Diameter of growth inhibition zone (mm)

Escherichia coli(Gram-negative)

Staphylococcus aureus(Gram-positive)

ara

EGS

3

(

4

rsXewcsGapa

Duy, N.N., Du, D.X., Phu, D.V., Quoc, L.A., Du, B.D., Hien, N.Q., 2013. Synthesis of gold

GNPs 18 19Ciprofloxacin 30 35

ntioxidant activities against NO assay than other assays. Theseesults are well agreement with reported works for evaluation ofntioxidant activities of GNPs (Naveena and Prakash, 2013).

Next, the antibacterial activities of GNPs were tested against. coli and S. aureus at 100 �g/mL using the disc diffusion method.NPs exhibited moderate zones of inhibition against both E. coli and.aureus when compared with standard ciprofloxacin (Table 2).

.1. Statistical analysis

The data were reported as mean values ± standard deviationMicrosoft Excel programme for Windows, v.2000).

. Conclusion

We describe a novel method for biosynthesizing GNPs via theeduction of aqueous AuCl4− ions using H. dulcis fruit extracts. Theynthesized GNPs were characterized by UV–vis, FT-IR, TEM andRD to identify their sizes and shapes. The devised method is annvironmentally benign and green protocol for preparation of GNPsith bioactive molecules without the use of any toxic reducing and

apping chemicals. Furthermore, the current method is inexpen-ive and suitable for the large-scale production of biologically activeNPs. The synthesized GNPs exhibited promising anti-oxidant and

ntimicrobial activities against both test microorganisms. Theseoly shaped GNPs can be used for drug delivery as well as medicinalpplications.

83.22 ± 0.19 83.43 ± 0.10 0.705 ± 0.61

wer.

Acknowledgements

This research was supported by the Nano Material TechnologyDevelopment Program of the Korean National Research Foundation(NRF) funded by the Korean Ministry of Education, Science, andTechnology (2012M3A7B4049675).

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