Ternary Bi2WO6/TiO2–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 Bi2WO6/TiO2–Pt heterojunction sonosensitizer achieved through the precise growth of Pt nanocrystals on a directionally assembled Bi2WO6/TiO2 Z-scheme structure. The construction of the Bi2WO6/TiO2–Pt heterojunction involves directional growth of Bi2WO6 in situ on the highly exposed (001) crystal facet of TiO2 nanosheets, followed by the precise deposition of nano Pt on the edge (101) crystal facet. The Z-scheme Bi2WO6/TiO2 in the ternary heterojunction ensures effective electron separation, while the Schottky TiO2–Pt interface establishes a well-defined charge flow path and robust redox capabilities. Moreover, nano Pt confers the Bi2WO6/TiO2–Pt heterojunction with excellent peroxidase-mimic and catalase-mimic activities, facilitating interactions with endogenous H2O2 to produce the hydroxyl radicals and O2. It effectively alleviates tumor hypoxia and enhances ROS production. This results in significantly higher efficiency in sonodynamically induced ROS generation compared to pure TiO2 or binary Bi2WO6/TiO2 heterojunctions, as confirmed by DFT theoretical calculation and experiments with both in vitro and in vivo anticancer performance. This study offers valuable insights for designing high-performance Z-scheme sonosensitizer systems.