Synthesis of Silver Nanoparticles using Leaf Extract of Andrographis paniculata
In the present investigation, an attempt was made to prepare nanoparticle by
using a medicinally important plant Andrographis paniculata. Because
now the biologically synthesized nanoparticle have been widely used in the field
of medicine. Silver nitrate (AgNO3) was used to synthesis the silver
nanoparticle by using leaf extract of Andrographis paniculata. The synthesized
silver nanoparticle from 1 mM AgNO3 solution through the leaf extract
were characterized using UV-Vis Spectrophotometry, XRD, SEM and FTIR. X-ray
diffraction and SEM analysis showed the average particle size of 28 nm with
cubic and hexagonal shape and it confirmed the formation of nanoparticle in
the sample. The synthesized silver nanoparticle can be used for various applications
due to its eco-friendliness, non toxic and compatibility for pharmaceutical
and other applications.
April 02, 2012; Accepted: May 07, 2012;
Published: June 26, 2012
There is growing need to develop eco-friendly and body benign nanoparticle
synthesis process without use of toxic chemicals in the synthesis of protocols
to avoid adverse effects in biomedical applications (Ankamwar,
2010). Nanometal particles, especially silver, have drawn the attention
of researchers (Safaepour et al., 2009). Because
of their extensive application in the development of new technologies in the
areas of electronics, material sciences and medicine at the nanoscale (Magudapathy
et al., 2001). Silver nanoparticles have many applications; for example,
they might be used as spectrally selective coatings for solar energy absorption
and intercalation material for electrical batteries, as optical receptors, as
catalysts in chemical reactions, for biolabelling and as antimicrobials (Joerger
et al., 2000; Panacek et al., 2006).
Many reports well documented on the biogenesis of silver nanoparticles using
several plant extracts. The reducing property of different plant constituents
may play a critical role in the reduction of Ag+ to silver nanoparticles
(Shankar et al., 2004). The use of environmentally
benign materials like plant leaf extract (Parashar et
al., 2009), bacteria (Saifuddin et al., 2009),
fungi (Bhainsa and DSouza, 2006) and enzymes (Willner
et al., 2007) for the synthesis of silver nanoparticles offers numerous
benefits of eco-friendliness and compatibility for pharmaceutical and other
biomedical applications as they do not use toxic chemicals for the synthesis
protocol. Chemical synthesis methods lead to presence of some toxic chemical
absorbed on the surface that may have adverse effect in the medical applications.
Green synthesis provides advancement over chemical and physical method as it
is cost effective, environment friendly, easily scaled up for large scale synthesis
and in this method there is no need to use high pressure, energy, temperature
and toxic chemicals. Therefore, the objective of this present study was to synthesis
the biologically active nanoparticle from the leaf extract of medicinal plant
MATERIAL AND METHODS
Plant materials: The plant Andrographis paniculata were collected
from the campus of Rajah Serfoji Govt. College in Thanjavur (DT) Tamil Nadu
during October to December 2011.
Preparation of the extract: Andrographis paniculata leaf were
collected and used to prepare the aqueous extract. Leaf weighing 25 g were thoroughly
washed in distilled water, dried, cut into fine pieces and were crushed into
100 mL sterile distilled water and filtered through Whatman No.1 filter paper
(pore size 25 μm). The filtrate was further filtered through 0.6 μm
Synthesis of silver nanoparticles: One millimole aqueous solution of
silver nitrate (AgNO3) was prepared and aqueous extract of leaf of
Andrographis paniculata used for the synthesis of silver nanoparticles.
10 mL of Andrographis paniculata leaf extract was added into 90 mL of
aqueous solution of 1 mM silver nitrate for reduction into Ag+ ions
and kept at room temperature for 5 h.
UV-Vis spectra analysis: The reduction of pure Ag+ ions was
monitored and measured in the UV-Vis spectrophotometer UV-2450 (Shimadzu).
XRD measurement: The silver nanoparticle solution thus obtained was
purified by repeated centrifugation at 5000 rpm for 20 min followed by redispersion
of the pellet of silver nanoparticles into 10 mL of deionized water. After freeze
drying of the purified silver particles, the structure and composition were
analyzed by XRD and SEM. The dried mixture of silver nanoparticles was collected
for the determination of size of Ag nanoparticles. Pro X-ray diffract meter
operated at a voltage of 40 kV and a current of 30 mA with Cu Kα radiation
in a θ-2θ configuration. The crystallite domain size was calculated
from the width of the XRD peaks, assuming that they are free from non-uniform
strains, using the Scherrer formula:
where, D is the average crystallite domain size perpendicular to the reflecting
planes, λ is the X-ray wavelength, β is the Full Width at Half Maximum
(FWHM) and θ is the diffraction angle.
Scanning electron microscopic (SEM) analysis of silver nanoparticles:
SEM analysis was done using Hitachi S-4500 SEM machine. Thin films of the sample
were prepared on a carbon coated copper grid by just dropping a very small amount
of the sample on the grid, extra solution was removed using a blotting paper
and then the film on the SEM grid were allowed to dry by putting it under a
mercury lamp for 5 min.
FTIR analysis of dried biomass after bioreduction: The residual solution
of 100 mL after reaction was centrifuged at 5000 rpm for 10 min and the resulting
suspension was redispersed in 10 mL sterile distilled water. The centrifugation
and redispersing process was repeated three times. Thereafter, the purified
suspension was freeze dried to obtain dried powder. Finally, the dried nanoparticles
were analyzed by FTIR, Nicolet Avatar 660 (CECRI, Karaikudi).
The synthesized nanoparticles using Andrographis paniculata leaf extract
exhibited a reddish brown color in aqueous solution due to excitation of surface
plasmon vibrations. While the leaf extract of Andrographis paniculata
mixing with the aqueous solution of the silver ion complex, it started to change
the color from watery to yellowish brown due to reduction of silver ion (Fig.
1). The absorption spectrum of aqueous silver nitrate only solution exhibited
maximum at about 220 nm and there was no color change. The synthesized AgNO3
nanoparticle were detected by UV-Vis spectroscopy at various nm 200, 300,
400, 500 and 600 nm, the particle has increasingly sharp absorbance maximum
peak at 280 nm and gradually decreased while nanometer increased (Fig.
2). Andrographis paniculata was found to exhibit very strong absorption
peaks at 400 to 500 nm. Absorption spectra of Ag nanoparticles formed on the
reaction mixture at different time intervals at 280 nm. The particle has increasing
sharp between 1 to 5 h the gradually decreased while the time has increased.
The UV-Vis spectra recorded from the reaction medium after 5 h, the light absorption
was more due to presence of nanoparticle formed in the reaction media and were
showed strong absorbance peaks at 280 nm (Fig. 2). Broadening
of peak indicated that the particles are poly dispersed. The biosynthesized
silver nanostructure by employing Andrographis paniculata leaf extract
was further demonstrated and confirmed by the characteristic peaks observed
in the XRD image (Fig. 3) and the structural view were observed
under the scanning electron microscope (Fig. 4). The XRD pattern
showed three intense peaks in the whole spectrum of 2θ values ranging from
10 to 80. The typical XRD pattern (Fig. 3) reveled that the
sample contains a mixed phase (cubic and hexagonal) structures of silver nanoparticles
(Fig. 4). The average estimated particle size of this sample
was 28 nm derived from the FWHM of peak (Fig. 3). The SEM
image showed the high density silver nanoparticles synthesized by the A.
paniculata development of silver nanostructures. FTIR analysis was used
for the characterization of nanoparticles.
||Synthesis of nanoparticle using silver nitrate and leaf extract
of Andrographis paniculata a: Leaf extract, b: 1 mM AgNO3
without leaf extract and c: 1 mM AgNO3 with 10% leaf extract
after 5 h
||UV-Vis absorption spectrum of leaf extract synthesized by
treating 1 mM aqueous AgNO3 solution with 10% Andrographis
paniculata leaf extract after 5 h
||XRD pattern of silver nanoparticles synthesized by treating
10% Andrographis paniculata with 1 mM aqueous AgNO3 solution
|| SEM micrograph of silver nanoparticles
FTIR absorption spectra of water soluble extract before and after reduction
of Ag ions are shown in Fig. 5. Absorbance bands in Fig.
5a (before bioreduction) are observed in the region of 500-3500 cm-1
are 3354.04, 2925.22, 2858.42, 1650.24, 1541.04, 1450.97, 1323.46, 1244.31,
1153.67, 1030.04, 608.35 cm-1.
||FTIR graph of (a) Leaf extract and (b) Nanoparticles synthesized
in 10% leaf extract solution
These absorbance bands are known to be associated with the stretching vibrations
for -C C-C O, -C C- [(in-ring) aromatic], -C-C- [(in-ring) aromatic], C-O (esters,
ethers) and C-O (polyols), respectively. In particular, the 1244 cm-1
band arises most probably from the C-O group of polyols such as hydroxyflavones
and catechins. The total disappearance of this band after the bioreduction (Fig.
Silver nanoparticle was synthesized from the leaf of Andrographis paniculata.
Rao and Savithramma (2011) revealed the synthesis nanoparticles
from leaf of Svensonia hyderabadensis and leaves of Allium cepa
by Saxena et al. (2010) and Clerodendrum inerme
by Farooqui et al. (2010) and in Argemone
mexicana (Khandelwal et al., 2010). Leaf
extract of Andrographis paniculata while mixing with the aqueous solution
of the silver ion complex, it started to change the color from watery to yellowish
brown. Which indicated the formation of silver nanoparticles and this might
be due to the reduction of silver ion to form the nanoparticles. Similarly,
Elumalai et al. (2010) observed that the reduction
of silver ion in Ag nitrate exposed plant extract followed by color change and
Rao and Savithramma (2011) also reported that the Svensonia
hyderabadensis solution of the silver ion complex started to change the
colour from yellow to dark brown due to reduction of silver ions. Silver nanoparticles
exhibited yellowish brown colour in aqueous solution due to excitation of surface
plasmon vibrations (Shankar et al., 2004). Chen
et al. (2002) observed the intensity of color development in the
reaction mixture of different plants such as in Helianthus annuus (sunflower),
Basella alba (spinach) and Saccharum officinarum (sugarcane).
Further, who stated that the synthesized AgNO3 nanoparticle were
detected by UV-Vis spectroscopy at various nanometers and the particle has increasingly
sharp absorbance and the peak was maximum at 280 nm and then it was gradually
decreased while nanometer increased. Andrographis paniculata was also
found to exhibit very strong absorption peaks at 400 to 500 nm. and the absorption
spectrum of aqueous silver nitrate only solution exhibited maximum at about
220 nm and there was no color change. Rao and Savithramma
(2011) reported that the UV-Vis spectrophotometric measurements were showed
strong absorption peak at 300 to 400 nm.
Chen et al. (2002) suggested that the difference
in the morphology of the synthesized nanoparticle might be a reason for the
variations in the absorption peaks.
The biosynthesized silver nanostructure by employing Andrographis paniculata
leaf extract was further demonstrated and confirmed by the characteristic peaks
observed in the XRD image and the structural view were observed under the scanning
electron microscope. The average estimated particle size of this sample was
28 nm derived from the FWHM of peak. The SEM image showed the high density silver
nanoparticles synthesized by the A. paniculata development of silver
nanostructures. FTIR analysis was used for the characterization of the extract
and the resulting nanoparticles. FTIR absorption spectra of water soluble extract
before and After reduction of Ag ions. Absorbance bands are observed in the
region of 500-3500 cm-1. Saifuddin et al.
(2009) observed the FTIR measurements to identify the possible biomolecules
responsible for capping and efficient stabilization of the metal nanoparticles
synthesized in leaf broth. The beaks near 3354.04, 2925.22 and 2858.42 cm-1
assigned to OH stretching and aldehydic C-H stretching, respectively (Jain
et al., 2009). The total disappearance of this band after the bioreduction
may be due to the fact that the polyols are mainly responsible for the reduction
of Ag ions, where by they themselves get oxidized to unsaturated carbonyl groups
leading to a broad peak at 1650.24 cm-1. The weaker band at 1244.31
cm-1 corresponds to amide I arising due to carbonyl stretch in proteins
(Sathyavathi et al., 2010). The result of all
earlier research strongly support the need of preparation of silver nanoparticle
from the medicinally important medicinal plants for various medicinal uses.
Synthesis of silver nanoparticle from the leaf of Andrographis paniculata
was confirmed by the colour changes from yellow to dark brown. Which indicated
the formation of silver nanoparticles. Therefore, the growing need of developing
a eco-friendly nanoparticle synthesis is possible and it can be used for various
biomedical applications to avoided the adverse effects chemically synthesized
nanoparticle in the filed of medical applications.
The authors are thankful to the U.G.C, New Delhi for providing financial assistance
and the Director, Central Electro Chemical Research Institute, Karaikudi, Tamil
Nadu for providing analytical facilities.
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