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 (Bi 2 S 3 )-titania (TiO 2 ) heterostructure is designed based on the excellent photothermal property of Bi 2 S 3 , which could improve intratumor oxygen content through increasing blood flow with the help of near infrared light. Bi 2 S 3 -TiO 2 heterostructure nanoparticles (NPs) present similar photothermal performance to Bi 2 S 3 NPs, while Bi 2 S 3 -TiO 2 NPs show higher reactive oxygen species (ROS) generating ability than Bi 2 S 3 NPs under ultrasonic irradiation. In vitro assessments proved that Bi 2 S 3 -TiO 2 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, Bi 2 S 3 -TiO 2 NPs can effectively improve oxygen content at 8 h post 808 nm laser irradiation. The tumor growth inhibition rate of Bi 2 S 3 -TiO 2 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 Bi 2 S 3 -TiO 2 heterostructure NPs realizes photothermal amplified sonodynamic therapy, providing a potential strategy for treating hypoxic tumors.