Green Synthesis of Silver/Silver Chloride Nanoparticles Mediated by Alternanthera philoxeroides Leaf Extract and Their Biological Activity

Abstract: Silver nanoparticles (AgNPs) were biosynthesized from Alternanthera philoxeroides leaf extract. Green synthesis of silver nanoparticles was done by mixing plant extract with AgNO₃ solutions. Surface plasmon resonance and energy dispersive X-ray spectroscopy data revealed the formation of AgNPs. X-Ray beam diffraction data provided information about the crystalline nature of synthesized silver nanoparticles. Fourier transform infrared spectroscopy ratified the presence of an amine phenolic, higher degree of unsaturation, and protein-containing biomolecules, which were responsible for the reduction and capping of nanoparticles during synthesis. Field emission scanning electron microscopy data revealed the spherical morphology of synthesized AgNPs. High-resolution transmission electron microscopy study of the nanoparticles suggested its almost spherical structure with sizes ranging from 7.4 to 35.6 nm with a median particle size of 14.63 nm. Antioxidant activity was studied by DPPH assay method, while antibacterial activity was conducted by using the agar well diffusion method against Escherichia coli, Staphylococcus aureus, Salmonella abony, and Bacillus subtilis. The results showed that the antioxidant and antibacterial properties of AgNPs are higher than those of plant extract, which shows its potential use in biomedical applications.