PDMS/γ-Bi₂O₃/SiO₂ coatings with superior antibacterial properties and mechanical durability based on friction-induced strategy

Recent public health issues and the rise of antimicrobial resistance have driven the demand for durable, self-activating antimicrobial surfaces. Traditional metal oxide coatings often suffer from uncontrolled ion release and limited antibacterial mechanisms, which hinder their long-term effectiveness. In this work, a mechanically robust, friction-activated hydrophobic antibacterial coating is developed by integrating γ-Bi₂O₃, polydimethylsiloxane (PDMS), and nanoscale hydrophobic SiO₂. PDMS imparts low surface energy, while SiO₂ reinforces mechanical stability; substrate adhesion is further enhanced via plasma treatment followed by KH570 silane grafting. Microscale tetrahedral γ-Bi₂O₃ (∼6 μm) with nanoscale tips (∼200 nm) enables a synergistic antibacterial effect through controlled Bi ⁺ release and mechanical membrane disruption, while maintaining low cytotoxicity. Upon friction activation, the P₁B₂S_0.04 coating exhibited an increase in water contact angle from 113.1 ± 1.7 ° to 145.9 ± 3.7 ° after 1000 abrasion cycles. The antibacterial rates against E. coli reached 99.94 %, 99.67 %, and 99.87 %, and S. aureus values were 97.77 %, 99.08 %, and 99.29 % after 300, 600, and 900 cycles, respectively. Cytotoxicity tests confirmed good biocompatibility, with cell viability exceeding 80 %. These results indicate that the coating maintains sustained antibacterial performance after repeated abrasion, showing strong potential for applications on medical and public surfaces.