Synergistic eradication of implant-associated infections by a copper phosphide film via bacterial metabolic collapse and oxidative burst.

Implant-associated infections caused by bacterial biofilms significantly limit the clinical utility of nickel-titanium (NiTi) alloys. Existing antimicrobial coatings often suffer from limited efficacy, poor biocompatibility, or non-selective killing mechanisms. To address these issues, a novel Cu3P-based film is fabricated on NiTi substrates through a combined approach of copper plasma immersion ion implantation and gas-phase phosphorization. This film can specifically cause bacterial metabolic collapse, which refers to ATP depletion caused by disrupted transmembrane proton motive force, and concurrently promote endogenous bacterial reactive oxygen species burst and glutathione depletion via controlled copper ion release. These synergistic effects can achieve over 99% eradication of both S. aureus and E. coli in vitro. Meanwhile, it exhibits excellent biocompatibility with mammalian cells due to the distinct mitochondrial energy metabolism pathway that distinguishes cells from bacteria. In vivo results from a rat subcutaneous infection model further confirm that the metal phosphide film effectively prevents infection and promotes tissue integration without causing inflammation or toxicity. This direct-contact and ion release synergistic antibacterial design concept provides theoretical insights for designing medical metallic implants with dual advantages of robust antibacterial performance and biosafety.