Antibacterial enhancement of Ag‑decorated silicon nanostructures synthesized by metal‑assisted chemical etching

Metal-assisted chemical etched (MACE) silicon nanostructures and their composites with Silver Nanoparticles (AgNPs) are investigated for antibacterial activity. Experimental results demonstrated a significant reduction in the Escherichia coli bacterial colony counts after exposure to the Si-Ag nano dendrite composite. While the pristine Si wafer exhibited an initial bacterial load of 90 colonies or 9 × 10 8 CFU/mL, vertically aligned Silicon nanostructures (VA-SiNSs ) reduced the count to 80 colonies or 8 × 10 8 CFU/mL (11.11% reduction), and Si-Ag nano dendrite composite achieved a further decrease to 65 colonies or 6.5 × 10 8 CFU/mL (27.78% reduction). Notably, the transition from VA-SiNSs to Si-Ag nano dendrite composite resulted in an additional 18.75% improvement in antibacterial efficiency. This enhanced antimicrobial behaviour is attributed to the combined effects of increased surface area, improved aspect ratio, and enhanced AgNPs distribution along the nanowire surfaces and pore ends, which enable more effective bacterial membrane disruption and biofilm penetration.