UV–vis spectroscopy
The formation and stability of Ag nanoparticles were followed by
UV–vis spectrophotometry (Cary, UV-50, Japan). The absorption spectrum
of reaction solutions as a function of reaction time and different
biomaterials and AgNO3 dosage at the same time were recorded at
wavelengths ranging from 300 to 600 nm. Distilled water was used as
a blank solution. Stability of bio reduced silver nanoparticles was analyzed
using UV–Vis absorption spectra. For this 4-fold diluted solution
was prepared.
2.4. Transmission electron microscopy
The transmission electron microscopy was applied for morphological
analysis of nanoparticles. 3 μl of the samplewas placed on the carbon
coated copper grid and kept for drying at room temperature. The TEM
images were obtained using a Philips cm10HT version of transmission
electron microscopy which operated at 100 kV.
2.5. X-ray diffraction measurements
Crystalline metallic pattern of silver nanoparticles powder was
analyzed using X-ray diffraction [63]. In order to obtain a pellet of
pure nanoparticles for XRD analysis, reaction medium was centrifuged
by five cycles at 18,000 rpm for 20 min followed by redispersion in DI
water. The X-ray diffraction (XRD) patterns were conducted on X'Pert
Pro MPD which operated at a voltage of 40 kV and a current of 40 mA
with Cu K(a) radiation. The scanning was done in the region of 2θ
from 20 to 80.
2.6. Fourier transforms infrared spectroscopy
FT-IR was used for determining the biomolecules present on the
seed extracts of C. officinalis. AgNPs were purified by repeating centrifugation
thrice at 18000 rpm for 30 min. FTIR analysis was used
for dried powder of AgNPs by scanning it in the range of 450–4000
at a resolution of 4 cm−1. The sample was added to KBr.