Aerva lanata flower extract mediated green synthesis of silver nanoparticles: Their characterization, in vitro antioxidants and antimicrobial investigations

Abstract The production of nanoparticles ( NPs ) using biological methods may lead to the enhancement of clean, non‐hazardous, and environmentally acceptable procedures. With this context, in the present study silver nanoparticles ( AgNPs ) were synthesized using the flower extract of Aerva lanata ( A. lanata ). The following techniques, including UV –visible spectroscopy, XRD , Scanning Electron Microscopy ( SEM ), and Fourier Transform Infrared Spectroscopy ( FTIR ), are used to study the crystalline nature, size, shape, and elemental composition of the biosynthesized AgNPs , and antimicrobial applications of the NPs also studied. In UV –visible spectroscopy results a strong absorbance peak at 425 nm confirmed the AgNPs . The SEM results confirmed the spherical shape of the NPs and their average size of 45.05 nm. X‐ray diffractometry XRD spectra confirmed the crystalline nature of the AgNPs . Against the DPPH (2,2‐diphenyl‐1‐picrylhydrazyl), nitric oxide and superoxide radicals, Alf‐AgNPs and ascorbic acid had significant scavenging effects at higher concentration of 250 μg/ mL , exhibited 65.76 ± 0.41% and 86.42 ± 0.69%, 78.39 ± 0.49% and 72.72 ± 0.14% and 70.79 ± 0.87% and 72.79 ± 0.33% inhibition, respectively. As produced AgNPs had strong antibacterial and moderate antifungal activities against pathogenic test bacterial strains viz. Staphylococcus aureus ( S. aureus ), Bacillus subtilis ( B. subtilis ), Escherichia coli ( E. coli ), and Klebsiella pneumonia ( K. pneumonia ) with the maximum zone of inhibition 15 ± 1.07 mm, 12 ± 0.96 mm, 14 ± 1.05 mm, and 15 ± 2.54 mm, respectively at maximum (75 μg/ mL ) concentration of AgNPs , and the zone of inhibition of fungal strains Aspergillus fumigatus ( A. fumigatus ) (9 ± 0.67 mm) and Candida albicans ( C. albicans ) (7 ± 0.75 mm) at 75 μg/mL. It was eventually concluded that the biosynthesized Alf‐AgNPs showed promising antioxidant and antimicrobial agents with very low concentrations.