Green Synthesis of Well Dispersed Nanoparticles using Leaf Extract of Medicinally useful Adhatoda Vasica Nees

192 Micro and Nanosystems, 2012, 4, 192-198 

Green Synthesis of Well Dispersed Nanoparticles using Leaf Extract 

of Medicinally useful Adhatoda Vasica Nees 

V. Karthick a , V. Ganesh Kumar a,* , T. Maiyalagan b , R. Deepa a , K. Govindaraju a , A. Rajeswari a and 

T. Stalin Dhas a 

a Nanoscience Division, Centre for Ocean Research, Sathyabama University,Chennai - 600 119, India 

b School of Chemical and Biomedical Engineering, Nanyang Technological University, 70 Nanyang Drive Singapore - 

639798 

Abstract: Development of reliable method for the green synthesis of gold nanoparticles (AuNPs) using medicinally 

valued Adhatoda vasica Nees has been studied here. The color change and the Surface Plasmon Resonance (SPR) 

confirmed the formation of AuNPs. The biosynthesized AuNPs were characterized using UV-visible Spectroscopy 

(UV-vis), Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), Scanning Electron Microscopy 

(SEM), Energy Dispersive Spectroscopy (EDAX) and Transmission Electron Microscopy (TEM) analysis. 

The nanoparticles synthesized were predominantly monodisperse, stable spherical in nature with well-defined dimensions 

of size ranging from 22 to 47 nm. The crystalline nature of the synthesized particles was also evident by the X-ray 

diffraction analysis. 

Keywords: Adhatoda vasica, Gold nanoparticles, Biosynthesis, Electron Microscopy, Diffraction. 

INTRODUCTION 

Nanobiotechnology combines biological principles with 

physical and chemical procedures to generate nano-sized 

particles with well defined functions. Particles of 

interestingly small size make the field of drug delivery more 

interesting and effective. Synthesizing gold particles 

(AuNPs) with medicinal applications is the recent trend in 

the field of nanobiotechnology. The surface availability of 

nanoparticles for binding/reactivity of other species on them 

is an important function as it is synthesized in different 

structures like nanorods, spheres, prims and hexagons. The 

controlled growth of AuNPs of different morphologies and 

the various chemical mechanisms involved in the anisotropic 

growth were studied using different chemical procedures [1]. 

The low toxicity effects of green synthesized AuNPs on 

biological systems made researchers to synthesize it by 

biological method rather by chemical means. Extensive 

studies were done on AuNPs and its binding affinity towards 

nucleic acids and proteins in biological systems [2]. AuNPs 

have been synthesized from various sources like plants [3], 

microbes [4], seaweeds [5] and microalgae [6]”. Sastry et al., 

2007 have synthesized AuNPs using chitosan and showed 

good control on postprandial hyperglycemia which when 

loaded with insulin [7] proved AuNPs to be an effective drug 

carrier. AuNPs can be used for the detection of nucleic acids 

as Chandirasekar and co-worker have, 2011 synthesized 

AuNPs using bile salts and particles with different geometry 

was achieved by varying the reducing agent concentration 

[8]. AuNPs have also been employed in the imaging of 

cancer cells like AR42J pancreatic tumor cells by 

synthesizing it using laser ablation technique and reported 

that size of AuNPs plays a role in the intracellular uptake [9]. 

*Address correspondence to this author at the Nanoscience Division, Centre 

for Ocean Research, Sathyabama University,Chennai - 600 119, India; 

Tel: +91 44 24500646; Fax: +91 44 24503308; E-mail: ganesv@gmail.com 

Adhatoda vasica Nees, a malabar nut tree belonging to 

the family Acanthaceae is native of South Asia and is 

exclusively studied for its active components like 

quinazoline alkaloids, vasicine, vasicinone, deoxyvasicine, 

oxyvasicinine, maiontone and other essential oils. The plant 

parts have been traditionally used for curing diseases like 

stomatitis, asthma and bronchititis [10]. The compound 

73/602 an alkaloid isolated from the leaves and roots of A. 

vasica is a structural analogue of vasicinone which shows 

appreciable antiallergic activity in mice, rats and guinea pigs 

[11]. Synthesis of AuNPs using medicinally useful plants 

[12, 13] is gaining more importance in therapeutic 

applications, where the reducing agent responsible for the 

reduction of chloroauric acid will have its own effect on 

biological systems. In our previous work, we have 

demonstrated the use of antidiabetic potent plant Cassia 

auriculata for the synthesis of AuNPs [14]. Herein, we have 

used an antiallergic potent plant A. vasica for the synthesis of 

AuNPs which may possess antiallergic effect on animals and 

that will be a welcoming outcome in the field of drug 

delivery. 

MATERIALS USED 

Chloroauric acid (HAuCl 4·3H 2 O) was obtained from 

Loba Chemie, India was used as received. All other reagents 

used in the reaction were of analytical grade with maximum 

purity. A. vasica Nees leaves were collected from forest area 

of Vellore, Tamilnadu, India and was cleaned with tap water 

and double distilled water twice to remove the dust. Further, 

it is shade dried for a week at room temperature and 

powdered for use. 

SYNTHESIS OF GOLD NANOPARTICLES 

For the preparation of A. vasica leaf extract, 4 g of 

powdered leaves is taken in a conical flask along with 40 mL 

of distilled water. The flask is then placed in an orbital 

shaker for 4 h and then the extract is taken by filtering the 

1876-4037/12 $58.00+.00 © 2012 Bentham Science Publishers

Green Synthesis of Well Dispersed Nanoparticles Micro and Nanosystems, 2012, Vol. 4, No. 3 193 

Fig. (1A). Aqueous extract of A. vasica (B) Chloroauric acid solution (C) Ruby red colour indicating the formation of gold nanoparticles. 

Fig. (2). UV-vis spectrum of the gold nanoparticles recorded immediately after synthesis (after 5 min). 

whole content using whatman No.1 filter paper. The filtrate 

is then stored in refrigerator for further use. The reaction is 

carried out using different concentrations of plant extract and 

finally optimized to a ratio of 1:10 (Extract: Chloroauric acid 

solution). Further 3 mL of extract is added to 30 mL aqueous 

solution of chloroauric acid (10 -3 M) and kept in an orbital 

shaker at room temperature. Formation of AuNPs takes place 

within 4 min, evident from the development of a stable ruby 

red color (Fig. 1) in the solution indicates the reduction of 

Au 3+ to Au 0 with no color change further. The experiment was 

repeated thrice to check the formation of AuNPs. The 

synthesized AuNPs are stable at a pH range of 3.6-9.1 showed 

no precipitation and color change for a period of 45 days. 

CHARACTERIZATION OF GOLD NANOPARTICLES 

The UV-vis spectra were recorded using Thermo 

Scientific Spectrascan UV 2700 with samples in quartz 

cuvette. FT-IR of Perkin Elmer spectrophotometer was used 

to identify the possible groups responsible for the reduction 

of chloroauric acid at a resolution of 4 cm -1 in the range of 

4000-450 cm -1 and the FT-IR spectrum was recorded by 

employing KBr pellet technique using Perkin Elmer model- 

983/G detector double beam spectrophotometer. XRD 

pattern of the A. vasica reduced AuNPs was carried out using 

a Rich Seifert P3000 instrument operated at a voltage of 40 

kV with Cu K radiations. SEM-EDAX was studied to check 

the surface morphology and elemental analysis of the AuNPs 

using XL30 FESEM, Philips. TEM studies were carried out 

by drop coating AuNPs onto carbon-coated TEM grids using 

Philips Technai-10. 

RESULTS AND DISCUSSION: 

The formation of AuNPs is noted down by the color 

change after the addition of aqueous extract to chloroauric 

acid solution as illustrated in (Fig. 1). The formation and 

stability of metal nanoparticles in aqueous solution is studied 

using UV-vis spectrophotometer. The surface plasmon 

resonance (SPR) arising due to the oscillation of free 

conduction electrons induced by the absorption of 

electromagnetic field [15] as a absorption band with a 

maximum at 532 nm has been observed in the spectrum 

(Fig. 2). To identify the possible functional groups 

responsible for the reduction of chloroauric acid the FT- 

IR spectrum is taken and the interaction of biomolecules have

194 Micro and Nanosystems, 2012, Vol. 4, No. 3 Karthick et al. 

Fig. (3). FT-IR spectra of dried powder of (A) A. vasica extract (B) gold nanoparticles. 

been studied (Fig 3). The spectrum show a clear difference in 

the functional group shifts. The peak seen at 3358 cm -1 

corresponds to the –OH or –COOH group which has shifted 

to higher wavelength 3687 cm -1 thus, implying that the –OH 

or –COOH group might have stabilized the AuNPs. 

The stretching of C=O can be observed in the spectrum 

indicating the red shift from 1625 to 1675 cm -1 . The 

peak 1406 cm -1 corresponds to the –COO - also shows a shift


Fig. (4). Diffraction pattern of gold nanoparticles synthesized using A. vasica. 

Fig. (5A). SEM image shows the presence of bioorganic compounds involved in the reduction (B) EDAX showing strong signals for gold 

nanoparticles.


Fig. (6A&B). TEM image taken at various magnifications showing gold nanospheres. 

which confirms the contribution of carboxylate groups in the 

reduction. In the spectrum aromatic resonances have not 

been identified indicating the absence of aromatic groups in 

the stabilizing compounds. Thus by using FT-IR, it is 

concluded that –OH or –COOH, -C=O, -COO - groups has 

involved in the stabilization of AuNPs. The crystalline nature 

of AuNPs was examined using XRD where three diffraction 

peaks were observed in the 2 range of 10º to 70º which can 

be indexed as (111), (200) & (220) reflections of fcc (face 

centered cubic) matches with Joint Committee on Powder 

Diffraction Standards (JCPDS No: 04-0784) revealing that 

synthesized AuNPs are composed of pure crystalline gold as 

there is no other peak found (Fig. 4). The XRD patterns 

obtained were similar to the results reported earlier on 

AuNPs [16]. The particle size of the AuNPs formed were 

calculated using Debye-Scherrer equation 

D = K / cos 

Where D is the average crystalline domain size 

perpendicular to the reflecting planes, K the Scherrer 

constant with value from 0.9 to 1, is the wavelength of the 

X-ray source, is the full width at half maximum (FWHM) 

and is the Diffraction angle. From this equation, the 

particle size calculated was found to be 39 nm which is 

similar to the size observed in TEM image of the AuNPs. 

The surface morphology and the scale in which the size of 

the nanoparticle synthesized can be studied using the SEM. 

The presence of bioactive components responsible for the 

reduction of the chloroauric acid to AuNPs was revealed 

using SEM imaging (Fig. 5A). The image confirms the 

presence bioorganic compounds which has stabilized the 

AuNPs. The EDAX profile has showed strong signal for 

gold atoms (Fig. 5B) and weak signals for chlorine, oxygen, 

sodium and magnesium which implies that these signals 

might be from the biomolecules present in the aqueous 

extract. The morphology of the synthesized nanoparticles 

were determined by TEM image and shown in (Fig. 6A&B). 

For the analysis the image is taken in a random place on the 

grid and the morphology is observed carefully. The particles 

as seen in TEM image are triangular and spherical in shape


Fig. (7). Possible mechanism for the reduction of chloroauric acid by bioactive compounds. 

with an average size of 38 nm with many similar sized 

particles except a few. The uniformity in size is a welcoming 

result in the green synthesis as in most of the cases the 

particle size varies with greater range which is a concern 

when applied in a targeted drug for therapeutic applications. 

The particle shape usually observed in most of the green 

synthesis is triangles and spheres and sometimes hexagon 

[14]. The synthesis of gold nanoprisms has been 

demonstrated [17] using a plant Cymbopogon flexuosus and 

a very clear image of prism structures have been observed in 

TEM. The possible mechanism for the stabilization of 

AuNPs is illustrated in (Fig. 7). However, finding the exact 

chemistry involved in reduction and elucidating the capping 

agent need further substantiation. 

CONCLUSION 

In the present work, a simple and more rapid method to 

procure gold nanospheres of monodisperse nature been 

displayed and its characterization has been discussed. In 

future, such rapid and eco-friendly method may help 

researchers to synthesize AuNPs using green synthesis than 

chemical methods. The formation of AuNPs in the reaction 

indicates the presence of bioactive compounds in the plants 

which are present on the surface of the AuNPs. Such 

compound rich AuNPs can be further used in therapeutic 

applications and it may have antiallergeic activity if tested on 

a suitable animal model. 

CONFLICT OF INTEREST 

The author(s) confirm that this article content has no 

conflicts of interest. 

ACKNOWLEDGEMENT 

We thank DST-Nanomission, Government of India for its 

financial support for the project (SR/NM/NS-06/2009) and 

the management of Sathyabama University, Chennai for its 

stanch support in research activities. 

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Received: April 02, 2012 Revised: May 18, 2012 Accepted: May 18, 2012

Green Synthesis of Well Dispersed Nanoparticles using Leaf Extract of Medicinally useful Adhatoda Vasica Nees

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