Biosynthesis of CuS nanozymes for synergistic antibacterial applications: Biosynthetic parameters optimization and...

The imperative to address antibiotic-resistant bacterial infections necessitates the development of novel antibacterial materials and methodologies, with nanozymes exhibiting peroxidase-like activity emerging as a highly promising option. Here, sulfate-reducing bacteria served  as bioreactors to biosynthesize copper sulfide nanoparticles (Bio-CuS NPs) via dissimilatory sulfate reduction pathways. By optimizing cultivation parameters such as pH, Cu²⁺ concentration, and carbon source, we successfully produced Bio-CuS NPs with a reduced size, enhanced crystallinity, and superior peroxidase-like activity. Comparative studies with chemically synthesized copper sulfide (Abio-CuS NPs) revealed that Bio-CuS NPs were coated with biomolecules, possessed a greater specific surface area, exhibited abundant sulfur vacancies, and demonstrated higher peroxidase-like activity. Leveraging these properties, Bio-CuS NPs demonstrated a 99.99 % antibacterial efficacy against Escherichia coli and Staphylococcus aureus within 2 h at low H₂O₂ concentrations (0.8 mM). The antibacterial mechanism was attributed to the synergistic generation of hydroxyl radicals (·OH) and the release of Cu²⁺, which sequentially disrupted bacterial cell structure and ultimately led to metabolic dysfunction. In addition, the antibacterial Bio-CuS NPs exhibited outstanding biocompatibility, rendering them highly suitable for environmental applications. This study established a green biosynthesis platform for the production of nanozymes, highlighting the potential of bio-nanoparticles as sustainable antimicrobial agents with dual advantages of eco-friendly production and catalytic bactericidal efficacy.