Bismuth-enhanced silicon nanowires: exploring their antimicrobial potential

• Synthesis of a novel antibacterial agent using a bismuth-modified silicon nanowires nanocomposite. • Demonstration of significant bacteriostatic and bactericidal effects of the nanocomposite. • In-depth investigation of antibacterial mechanisms, reaction kinetics, and recyclability of the nanocomposite. • Promising potential of bismuth-modified silicon nanowires for diverse biomedical applications. Targeted eradication of bacteria using nanomaterials has gained prominence as a solution to antibiotic-resistant microorganisms. A synergistic hybrid structure, integrating nanostructured surfaces with nanowire arrays and plasmonic metal nanoparticles, represents a promising approach. In this context, this study focuses on the functionalization of silicon nanowires (SiNWs) with bismuth nanoparticles (BiNPs) to design a novel and cost-effective antibacterial agent. High-density needle-like SiNWs were synthesized via metal-assisted chemical etching, with BiNPs anchored through thermal evaporation. Morphology, elemental composition, and structural analysis confirmed the formation of the BiNPs@SiNWs nanocomposite. The hydrophilic nature of BiNPs@SiNWs facilitates antifouling by reducing bacterial contamination. These nanocomposites exhibit outstanding absorbance, reaching 99%, particularly in the near-infrared range overlapping with three biological windows, promoting reactive oxygen species (ROS) generation and efficient solar-driven photothermal effects that harm bacteria. Antibacterial properties were assessed under natural solar irradiation against gram-negative Escherichia coli and gram-positive Staphylococcus epidermidis . Using colony-forming units, fluorescence staining, and scanning electron microscopy, remarkable bacteriostatic and bactericidal rates of 96% and 99%, were respectively observed. The mechanisms underlying these effects were thoroughly elucidated, showing sustained efficacy across multiple cycles. BiNPs@SiNWs display significant potential as a novel and efficient antibacterial agent for diverse biomedical applications.