Synthesis, Characterization, and Antimicrobial Studies of Zinc Oxide Nanoparticles of <I>Mangifera indica</I> Stem Bark

Abstract

The growing threat of antibiotic-resistant bacteria and the harmful effects of chemically synthesized nanoparticles on health and the environment have increased the need for green alternatives. This study presents the eco-friendly synthesis of zinc oxide nanoparticles (ZnO NPs) using extract from the stem bark of Mangifera indica and evaluates their antibacterial efficacy against clinical pathogens. The ZnO NPs were characterized using UV-Vis, FTIR, XRD, SEM, and other standard analytical techniques. Proximate analysis of the stem bark powder revealed ash (6.21%), moisture (29.54%), protein (10.35%), fibre (10.19%), fat (6.37%), and carbohydrate (18.74%). Phytochemical screening confirmed the presence of carbohydrates, tannins, cardiac glycosides, flavonoids, saponins, anthraquinones, and alkaloids. UV-Vis spectra showed strong absorption between 250–300 nm with a shoulder at 320–340 nm, while FTIR analysis identified functional groups such as O–H, C=O, and C–O. XRD patterns showed that the phase was pure and had a hexagonal wurtzite structure. Antimicrobial activity was tested at 10, 15, and 20 mg/ml against Pseudomonas aeruginosa, Bacillus cereus, Aspergillus fumigatus, Candida albicans, and Saccharomyces cerevisiae. The stem bark extract showed minimal inhibition at 10 mg/ml, while higher concentrations produced dose-dependent effects (ZOIs: 10.30 ± 0.263 mm to 14.11 ± 0.712 mm). The synthesized ZnO NPs demonstrated enhanced broad-spectrum activity (ZOIs: 5.8 ± 0.032 mm to 15.9 ± 0.171 mm). Overall, the study emphasizes the exciting prospects of Mangifera indica stem bark-derived ZnO NPs as a safe, sustainable, and effective antibacterial agent for combating multidrug-resistant pathogens.