Bismuth sulfide-titania heterostructure used for photothermal amplified sonodynamic therapy against hypoxic tumor.

Hypoxia and electron-hole recombination are two obstacles limiting sonodynamic therapeutic efficacy against cancer. Herein, bismuth sulfide (BiS)-titania (TiO) heterostructure is designed based on the excellent photothermal property of BiS, which could improve intratumor oxygen content through increasing blood flow with the help of near infrared light. BiS-TiO heterostructure nanoparticles (NPs) present similar photothermal performance to BiS NPs, while BiS-TiO NPs show higher reactive oxygen species (ROS) generating ability than BiS NPs under ultrasonic irradiation. assessments proved that BiS-TiO NPs could produce heat and ROS to damage mitochondrial, leading to cell death due to their synergetic photothermal and sonodynamic performances. After being administrated into tumor, BiS-TiO NPs can effectively improve oxygen content at 8 h post 808 nm laser irradiation. The tumor growth inhibition rate of BiS-TiO NPs with 808 nm laser or ultrasound irradiation is 77.49 ± 3.96 % and 63.64 ± 2.2.7 %, respectively, while it reaches up 88.82 ± 3.98 % when 808 nm laser and ultrasound are applied in sequence, proving the photothermal amplified sonodynamic therapeutic efficacy against hypoxic tumor. As a result, the design of BiS-TiO heterostructure NPs realizes photothermal amplified sonodynamic therapy, providing a potential strategy for treating hypoxic tumors.