Exploration of the catalytic, anti-bacterial, and anti-oxidant capabilities of environmentally conscious zinc oxide nanoparticles synthesized using Citrus sinensis

Abstract

Zinc oxide nanoparticles have been fabricated via a sustainable protocol from the fruit juice of Citrus sinensis. The SEM and TEM analyses were employed to ascertain the morphology and particle size of the nanoparticles, unveiling a spherical shape and a particle size ranging from 40 to 60 nm. XRD study suggested that the nanoparticles were crystalline. FT-IR analysis displayed bands for the possible phytochemicals involved in the bio-reduction and capping of the nanoparticles. The nanoparticles' ability to inhibit the growth of four bacterial strains-Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa was evaluated to determine their antimicrobial effectiveness. The nanoparticles showed significant anti-microbial action against the tested strains. DPPH assay was accomplished to evaluate the anti-oxidant activity of the nanoparticles, wherein a reasonable free radical scavenging ability of 65.87 % (IC50 = 366.37 μg/mL) was attained. The nanoparticles displayed substantial catalytic activity for the reduction of the organic dye-malachite green. The dye degradation of 91.87 % was achieved in 21 min and the reaction kinetics was pseudo-first-order. The nano-catalyst was reusable for three sequential cycles of the reduction reaction and no substantial decrease in its catalytic potential was observed. Hence, the eco-friendly approach to synthesizing zinc oxide nanoparticles proved to be successful and the nanoparticles exhibited an array of promising applications.