Green synthesis of antibacterial and antifungal silver nanoparticles using Citrus limetta peel extract: Experimental and theoretical studies

Abstract

Abstract Process byproducts of the fruit industry may represent an inexpensive and reliable source of green reducing and capping agents to be applied in current bio-nano synthesis. This study reports a novel method of one pot green synthesis of silver nanoparticles (AgNPs) from the Citrus limetta peel extract (CPE). UV–vis spectrophotometry, dynamic light scattering (DLS) and transmission electron microscopy (TEM) studies confirmed synthesis of AgNPs of average size 18 nm, which were stable up to 120 days. FTIR study suggested that alcoholic groups of CPE mainly responsible for the stabilization of AgNPs. Theoretical simulation using Density Functional Theory (DFT) indicated that among different alcoholic compounds of CPE, 3-allyl-6-methoxy phenol showed the highest interaction energy (128.49 KJ/mole) with AgNPs, and is mainly responsible for stabilization of the latter. The synthesized AgNPs have both antibacterial (Micrococcus luteus, Streptococcus mutans, Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli) and antifungal (candida species) activities with potent anti-biofilm and cell membrane permeabilization ability. These nanoparticles have superior antimicrobial potency than earlier reports specially against topical pathogens. Therefore, these AgNPs can be an effective alternative in pharmaceutical industries against topical pathogens.