Construction of chitosan-coated TiO2/In2S3 heterojunction on titanium surfaces for NIR triggered photothermal/photodynamic synergistic enhanced antibacterial.

Implant-associated bacterial infections remain a major challenge in orthopedic and dental applications, often compromising implant integration and longevity. For this reason, the synergistic antibacterial strategy of photothermal and photocatalysis has become one of the important methods in the field of antibacterial. To synthesize high-efficiency near-infrared (NIR) light-responsive catalysts, a titanium oxide/indium sulfide (TiO2/In2S3) heterojunction antibacterial coating was prepared on the titanium (Ti)-based surface using anodic oxidation and wet chemical deposition methods. Compared with Ti alloy, the TiO2/In2S3 heterojunction showed a suitable energy band structure, improved light absorption, and enhanced carrier separation capability, thus enhancing photothermal catalytic activity and promoting the production of bacterial reactive oxygen species (ROS) under NIR light. Indeed, the TiO2/In2S3 heterojunction narrowed the bandgap (∼2.5 eV) and efficiently generated ROS (•O₂⁻ and •OH) under NIR irradiation. Furthermore, the successful deposition of chitosan (CS) endowed the TiO2/In2S3 heterojunction with osteogenic activity, promoting the proliferation and differentiation of osteoblasts. In vitro, results demonstrated effective antibacterial performance against Escherichia coli and Staphylococcus aureus, inhibited biofilm formation, and supported collagen secretion and mineralization. In vivo, NIR irradiation raised the implant site temperature to below 50 °C, enabling safe and efficient sterilization, and showing no organ toxicity. These results highlight CS-coated TiO2/In2S3 heterojunction as a promising multifunctional coating that combines infection control with osteogenic support, providing a potential strategy for improving the safety and longevity of Ti-based implants.