Eco-friendly approach for biosynthesis of silver nanoparticles using Citrus maxima peel extract and their characterization, catalytic, antioxidant and antimicrobial characteristics

The present investigation was carried out to demonstrate a novel, simple, cost effective, and eco-friendly manner to synthesize silver nanoparticles (AgNPs) by Citrus maxima peel extract as both reducing and capping agents without using any hazardous substance. This process can be rapidly performed at room temperature. Comprehensive techniques were performed to characterize and quantify the biosynthesized AgNPs. Hence, UV–vis spectrum showed the surface plasmon resonance (SPR) band at 430 nm, confirming the formation of AgNPs. TEM image displayed the size of AgNPs ranged from 4 to 11 nm with spherical shapes. The XRD pattern proved the synthesized AgNPs were face-centered cubic (FCC) lattice. Furthermore, the analytical result of FTIR demonstrated that the bioactive compounds such as naringin, naringenin and hesperidin containing O–H functional groups in the extract might be responsible for the synthesis and stabilization of AgNPs. After ultrafilter centrifugation, the ICP-MS revealed yield of AgNPs about 99%. AgNPs showed good catalytic activity by degradation of 4-nitrophenol pollutant. In addition, these AgNPs exhibited appropriate antioxidant properties by scavenging the ABTS and DPPH free radicals due to the existence of biomolecules on surface of AgNPs as natural antioxidants. Finally, this study not only examined the antibacterial activity of AgNPs against Escherichia coli (Gram positive) and Staphylococcus aureus (Gram negative), but also explored the effect of AgNPs on plant pathogens like Fusarium oxysporum and Verticillium dahliae. For the first time, we observed that biosynthesized AgNPs well inhibited the growth of the V. dahliae. (paper)