Zinc Bismuthate-Based Nanocomposites: Promising Antimicrobial Properties for Biomedical Applications

The growing threat of antimicrobial resistance has intensified the search for new antimicrobial materials. In this work, zinc bismuthate-based nanocomposites (ZB1 and ZB4) were synthesized by a hydrothermal method and characterized using X-ray diffraction, Raman spectroscopy, zeta potential and high-resolution transmission electron microscopy. Structural analyses suggested the coexistence of a zinc oxide secondary phase and oxygen vacancies, which may influence the physicochemical and biological behavior of the materials. The antimicrobial activity was evaluated against Staphylococcus aureus, Corynebacterium diphtheriae, Klebsiella pneumoniae, Cryptococcus neoformans, and Candida albicans by disk diffusion. For C. diphtheriae and C. neoformans, additional minimum inhibitory concentration and minimum fungicidal concentration assays were performed. Both nanocomposites inhibited S. aureus, C. diphtheriae, and C. neoformans, while no inhibition was observed for C. albicans and K. pneumoniae. ZB4 exhibited superior antimicrobial activity, with growth inhibition observed up to 500 µg mL-1, whereas ZB1 was effective only at higher concentrations. Toxicity tests using Tenebrio molitor larvae revealed survival rates of approximately 70% for ZB1 and 60% for ZB4 after 10 days, with no statistically significant difference compared to the control. Overall, ZB4 presented promising antimicrobial activity with moderate toxicity, indicating its potential for biomedical applications.