Characterization of AgNPs
2.2. Characterization of AgNPs
Preliminary characterization of the AgNPs was carried out using
UV–vis spectroscopy. The measurement was carried out by using
a Jasco dual-beam spectrophotometer (model V-530, Japan) having
operational range of wavelength between 300 nm and 800 nm.
The synthesized AgNPs were characterized by UV–vis spectroscopy
periodically at different time intervals up to a month in order to
observe rapid reduction of silver nanoparticles by the action of
aqueous leaf extracts of Mimusops elengi, L. using constant 1 mM
AgNO3 solution. The colour change was observed in every minute
and the colour of the reaction mixture was set up to change from
light green to dark brown within 15 min.
This AgNPs dried at 50 ◦C for 6 h and mixed with KBr and convert
into a pellet form by using bench press. Thereafter the formed pellet
was used to test for functional groups by IR spectroscopy. In addition,
to identify which functional group is present in the aqueous
leaf extract causing the reduction? For that, the dry leaf powder of
Mimusops elengi, L. was pelletized and FTIR (Jasco 460 plus, Japan)
spectra were recorded between 4000 and 400 cm−1. The spectrum
of AgNPs in the aqueous extract and the spectrum for pure dry leaf
powder were compiled.
The size and morphological characterization of the synthesized
and lyophilized AgNPs were studied using scanning electron microscope
(SEM). A thin film was prepared by drop coating biologically
synthesized purified silver nanoparticles on to carbon coated copper
SEM grids. The thin film on the SEM grid was allowed to stand
for 5 min to dry prior to measurement and then the extra sample
solution was removed using a blotting paper. The SEM images
were recorded (JEOL-JEM 6390, Japan) at 40,000×
magnifications
operating with 20.00 kV. Furthermore, the X-ray thin film diffraction
measurement for bio-reduced AgNPs were also carried out
in a Goniometer = PW3050/60 (Theta/Theta) using Cu k radiation
which facilitate at 40 KV and 25 ◦C. Subsequently the X-ray patternswere obtained in the 2 range of 20–80 ◦C.