4-nitrophenolateion without a catalyst. In the presence of Ag NPs catalyst and NaBH
4
the 4-NP was reduced, and the intensity of the absorption peak at 400 nm decreased
gradually with time and after about 20-22 min it fully disappeared. At the same time,
a new absorption peak appeared at about 297 nm and increased progressively in
intensity.
This new peak is attributed to the typical absorption of 4-AP [8]. This result
suggests that the catalytic reduction of 4-NP exclusively yielded 4-AP, without any
other side products. Direct electrochemistry studies of the synthesized Ag,
Ag/Au.
MNPs
confirmed that nanoparticles retained their direct electrochemical activity.
This is mainly attributed to the proper biosynthesis process, the large specific surface
area and the good conductivity of the synthesized nanoparticles. Hence, the present
synthesized NPs displayed good electrocatalytic activity to the reduction of nitrite ions.
Figure 2. UV–vis spectra of the reduction of nitro compounds with NaBH
4
in the
presence of Ag NPs as a catalyst 4-Nitrophenol
Monometallic and bimetallic nanoparticles showed good antimicrobial activity
against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli)
bacteria Table 4.
The exact mechanism of action of Ag NPs as an antibacterial agent is not fully
revealed. However, some reports clearly suggests that the Ag NPs produces free
radicals and these radicals creates pores in the bacterial cell wall changing the
membrane permeability, and releases certain vital proteins and lipopolysaccharide
molecules.
The damages to the bacterial cells may be caused by the interaction of
AgNPs with phosphorus and sulfur-containing compounds such as DNA and proteins.
NPs have also been reported to inhibit the enzymes of electron transport chain in
bacteria, ultimately leading to the cell death. In the present study, we have only
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