Metastructure and strain-defect engineered Cu-doped TiO coating to enhance antibacterial sonodynamic therapy

Sonodynamic therapy (SDT) has attracted widespread attention in treatment of implant-associated infections, one of the key factors leading to implant failure. Nevertheless, constructing efficient ultrasound-triggered coatings on implant surfaces remains a challenge. Herein, an acoustic metastructure Cu-doped defective titanium oxide coating (Cu-TiO ) with lattice strain was constructed in situ on titanium implant to realize effective sonocatalysis. The redistribution of Cu atoms broke the pristine lattice of TiO₂ during the thermal reduction treatment to regulate its energy structure, which favored separation of electron-hole pairs generated by ultrasound radiation to enhance the sonocatalytic generation of reactive oxygen species. In addition, the acoustic metastructure enhanced the absorption of ultrasound by Cu-TiO metastructure coating, which further promoted its sonocatalytic effect. Thus, Cu-TiO metastructure coating could efficiently eliminate Staphylococcus aureus and Escherichia coli infections under ultrasonic irradiation in 10 min. Besides, the osteogenic property of implant was significantly improved after infection clearance in vivo. This work provides a fresh perspective on the design of SDT biosurfaces based on metastructure and strain-defect engineering.