Biosynthesis, Electrochemical, Antimicrobial and Antioxidant Studies of Silver Nanoparticles Mediated by Talinum triangulare Aqueous Leaf Extract

Silver nanoparticles (AgNPs) were synthesized using leaf extract of Talinum triangulare (TT). The nanoparticles were characterised using Infra-red spectroscopy, UV-vis spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The UV-vis spectrum showed the formation of surface plasmon bands (SPBs) between 417 and 430 nm. The X-ray diffraction (XRD) and transmission electron microscopy analysis showed spherically shaped nanoparticles with average size of 13.86 nm. Antimicrobial potentials of the silver nanoparticles, the leaf extract and AgNO3 were evaluated against Gram negative (Escherichia coli, Salmonella typhi), Gram positive (Bacillus subtilis and Staphylococcus aureus) bacteria strains and fungi organism, Candida albicans. The silver nanoparticles displayed better antimicrobial activities compared to the other samples. The antioxidant properties of the nanoparticles and crude leaf extract were investigated using DPPH radical scavenging assay. The AgNPs exhibited better DPPH radical scavenging activities compared to the leaf extract. Moreover, the antioxidant activity of the AgNPs compared favourably with that of ascorbic acid at the same concentrations. Furthermore, electrochemical studies involving TT-AgNPs/MWCNT (multiwalled carbon nanotubes) modified electrode and comparative cyclic voltammetry experiments with other modified electrodes (bare GCE, GCE/MWCNT and GCE/TT-Ag) showed that GCE/TT-AgNPs/MWCNT exhibited good conducting platform for electrocatalysis and a lower charge transfer resistance (R-ct).