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 _<i>x</i> ) with lattice strain was constructed <i>in situ</i> 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 _<i>x</i> metastructure coating, which further promoted its sonocatalytic effect. Thus, Cu-TiO _<i>x</i> metastructure coating could efficiently eliminate <i>Staphylococcus aureus</i> and <i>Escherichia coli</i> infections under ultrasonic irradiation in 10 min. Besides, the osteogenic property of implant was significantly improved after infection clearance <i>in vivo</i>. This work provides a fresh perspective on the design of SDT biosurfaces based on metastructure and strain-defect engineering.