Ternary BiWO/TiO-Pt Heterojunction Sonosensitizers for Boosting Sonodynamic Therapy.

Engineering Z-scheme heterojunctions represents a promising strategy for optimizing the separation and migration of charge carriers in semiconductor sonosensitizers for enhanced reactive oxygen species (ROS) generation. Nevertheless, establishing a continuous and directional pathway for ultrasonic-induced charge flow in Z-scheme heterojunctions remains a significant challenge. In this study, we present a ternary BiWO/TiO-Pt heterojunction sonosensitizer achieved through the precise growth of Pt nanocrystals on a directionally assembled BiWO/TiO Z-scheme structure. The construction of the BiWO/TiO-Pt heterojunction involves directional growth of BiWO in situ on the highly exposed (001) crystal facet of TiO nanosheets, followed by the precise deposition of nano Pt on the edge (101) crystal facet. The Z-scheme BiWO/TiO in the ternary heterojunction ensures effective electron separation, while the Schottky TiO-Pt interface establishes a well-defined charge flow path and robust redox capabilities. Moreover, nano Pt confers the BiWO/TiO-Pt heterojunction with excellent peroxidase-mimic and catalase-mimic activities, facilitating interactions with endogenous HO to produce the hydroxyl radicals and O. It effectively alleviates tumor hypoxia and enhances ROS production. This results in significantly higher efficiency in sonodynamically induced ROS generation compared to pure TiO or binary BiWO/TiO heterojunctions, as confirmed by DFT theoretical calculation and experiments with both and anticancer performance. This study offers valuable insights for designing high-performance Z-scheme sonosensitizer systems.