1.
Materials and methods Silver nitrate and DPPH were purchased from Sigma–
Aldrich, Merck. The media used for bacterial cultures was
Reagents
from Hi-media, Mumbai, India. All other reagents were of
AR grade.
0927-7765/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.colsurfb.2012.08.041
K.L. Niraimathi et al. / Colloids and Surfaces B: Biointerfaces 102 (2013) 288–291 289
Preparation of the extract
Fresh leaves of A. sessilis purchased were identified in
CARISM herbarium section, SASTRA University and
washed with double dis- tilled water. Cut into small
pieces, transferred to 1000 ml conical flask and boiled
with 150 ml of distilled water for 10 min. The con-
densed liquid was used for the synthesis of silver
nanoparticles. The liquid was analysed for its major
chemical constituents and used for the synthesis of
nanoparticles.
Synthesis of nanoparticles
3 mM solution of silver nitrate was prepared. 20 ml of
the plant extract was mixed with 80 ml of 3 mM of
silver nitrate solution. The colour changed from yellow
to reddish brown colour indicat- ing the formation of
silver nanoparticles. The AgNps thus obtained was Fig. 1. (A) Plant extract and (B) synthesized AgNPs.
purified by repeated centrifugation at 7000 rpm for 10
min. The pellet was collected and dried. The Chemical 2.50
2.4
tests were carried out in AgNPs for proteins and vitamin
2.2
C. The pH of the solution was also determined. 2.0
435.04
1.8
UV–vis spectra analysis 1.6
Absorbance
1.4
The reduction of pure silver ions was confirmed by A 1.2
measur- ing the UV–vis spectrum of the reaction mixture 1.0
against distilled water as a blank. The Spectral analysis 0.8
0.6
was done using double beam PerkinElmer
0.4
spectrophotometer at a resolution of 1 nm from 250 to 0.2
450 nm. 0.00
FT-IR analysis
PerkinElmer spectrometer FT-IR SPECTRUM means of laser diffractometry, using Zeta sizer nano-series
ONE in the range of 4000–400 cm−1 at a resolution (Malvern). Measure- ments were taken in the range between
of 4 cm−1 was used. The sample was mixed with 0.1 and 10,000 nm.
KBr procured from Merck chemicals. Thin sample
pellet was prepared by pressing with the Hydraulic
Antimicrobial activity
Pellet Press and subjected to FT-IR analysis.
Anti-microbial activity of the AgNPs was screened against
SEM analysis
Staphylococcus aureus and Escherichia coli by Baur et al.’s
method. Briefly, Overnight cultures of the bacterial strains were
Morphological characterization of the samples prepared in Luria broth. 150 µL (100 µg/ml) of the synthesized
was done using FE-SEM (JEOL JSM 6701-F). A AgNPs were filled in to the well and kept for incubation
pinch of dried sample was coated on a carbon tape. overnight at 37 ◦C.
It was again coated with platinum in an auto fine
coater and then the material was subjected to
analysis.
TG–DSC analysis
Thermo gravimetric differential scanning
colorimeter analysis was carried out using TG–
DSC (SDT Q600 model, TA Instruments, USA).
About 5 mg of the sample was taken in an alumina
cup holder and heated up to 1000 ◦C at the rate of
10 ◦C/min.
Particle size measurement
Particle sizing experiments were carried out by
350.0 360 380 400 420 440 460 480.0
nm
Wavelength (nm)
Fig. 2. UV–vis spectra of synthesized AgNPs
