3.2. Characterization of silver and gold nanoparticles
FT IR spectroscopic studies were carried out to investigate to
find possible bioreducing agents present in the extract. The spectra
of extracts were recorded before and after adding silver nitrate
(a) and chloroauric acid (b) solution (Fig. 3). Both the interferrogram
exhibit a broad at 3394 cm−1 is assigned to the N–H group
from peptide linkage present in the extract. Formation of C C
bonds is energetically favored over S C bonds, as the latter will
impose severe geometrical constraints on the molecule more specific
in thiol group and less in acidic as compared to alcohols
and that makes elimination of hydrogen attached to sulfur group.
There is a decrease in the concentration of the amide linkage
in the aqueous solution after the formation of silver nanoparticles.
According to the scanning electron micrograph, the morphology
of the silver and gold nanoparticles was observed and approximately
spherical, in which the silver nanoparticles is in aggregated
form (Fig. 4a). This reveals that the powder particles are slightly
agglomerated but its size range of 90 nm and the closed view of
spherical nanoparticle has showed and Fig. 5a is a micrograph of the gold nanoparticles indicating that they are also spherical in shape in
range of 150 nm. Above results suggested that the silver and gold
nanoparticles are synthesized due to the action of plant extract,
M. piperita, which act as good bioreductant for biosynthesis. In the
analysis by energy dispersive spectroscopy (EDS) of the silver and
gold nanoparticles the presence of elemental metal signal was con-
firmed. Although silver and gold signal are present, the presence of
silicon signal may be due to the thin film made on the glass slide
taken for the EDS (Figs. 4b and 5b).