Harnessing the power of Neobacillus niacini AUMC-B524 for silver oxide nanoparticle synthesis: optimization, characterization, and bioactivity exploration.

Background: Biotechnology provides a cost-effective way to produce nanomaterials such as silver oxide nanoparticles (Ag₂ONPs), which have emerged as versatile entities with diverse applications. This study investigated the ability of endophytic bacteria to biosynthesize Ag₂ONPs.

Results: A novel endophytic bacterial strain, Neobacillus niacini AUMC-B524, was isolated from Lycium shawii Roem. & Schult leaves and used to synthesize Ag₂ONPS extracellularly. Plackett-Burman design and response surface approach was carried out to optimize the biosynthesis of Ag₂ONPs (Bio-Ag₂ONPs). Comprehensive characterization techniques, including UV-vis spectral analysis, Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray diffraction, dynamic light scattering analysis, Raman microscopy, and energy dispersive X-ray analysis, confirmed the precise composition of the Ag₂ONPS. Bio-Ag₂ONPs were effective against multidrug-resistant wound pathogens, with minimum inhibitory concentrations (1-25 µg mL^-1). Notably, Bio-Ag₂ONPs demonstrated no cytotoxic effects on human skin fibroblasts (HSF) in vitro, while effectively suppressing the proliferation of human epidermoid skin carcinoma (A-431) cells, inducing apoptosis and modulating the key apoptotic genes including Bcl-2 associated X protein (Bax), B-cell lymphoma 2 (Bcl-2), Caspase-3 (Cas-3), and guardian of the genome (P53).

Conclusions: These findings highlight the therapeutic potential of Bio-Ag₂ONPs synthesized by endophytic N. niacini AUMC-B524, underscoring their antibacterial efficacy, anticancer activity, and biocompatibility, paving the way for novel therapeutic strategies.