Easy preparation of TiO2/TCPP/CS nanoparticles for effective antibacterial photodynamic therapy†

Abstract

Titanium dioxide (TiO₂) is an excellent photocatalyst known for its exceptional chemical stability and good biocompatibility. However, the poor visible light utilization of TiO₂ limits its application in the field of antibacterial therapy. In this study, TiO₂ was sensitized with tetracarboxyphenyl porphyrin (TCPP) to enhance its visible light adsorption, and an antibiotic-independent antibacterial material was developed that effectively reduces the formation of drug-resistant bacteria. TCPP was first used to narrow the bandgap of TiO₂ to produce ROS under visible light irradiation for antibacterial photodynamic therapy (APDT). Then, chitosan was selected to improve the dispersion and stability of TiO₂/TCPP in aqueous solution as well as to introduce a cationic surface to inhibit bacterial growth, creating a dual-functional TiO₂/TCPP/CS nanoparticle antibacterial system. In vitro antibacterial experiments demonstrated that TiO₂/TCPP/CS nanoparticles can eliminate both Gram-positive and Gram-negative bacteria under visible light irradiation. During in vivo experiments, the TiO₂/TCPP/CS-treated group exhibited mouse wound healing effects superior to those of the control group under visible light irradiation, indicating effective APDT ability. Overall, the TiO₂/TCPP/CS antibacterial system did not rely on antibiotics, suggesting that it has the ability to prevent the emergence of drug-resistant bacteria and resist the further evolution of superbacteria.