Acid-Responsive Bismuth Heterojunction Nanocatalyst for Photocatalytic and Photothermal Treatment of Tumors

Exogenous stimuli-activated catalytic therapies for cancer, such as photodynamic therapy, have significant clinical potential. Despite the recent progress, the low catalytic production efficiency of reactive oxygen species (ROS) and the overexpression of glutathione (GSH) in the tumor microenvironment (TME) are major challenges for exogenous stimulative catalytic therapy. Bismuth-based heterojunction nanomaterials can generate ROS under various exogenous stimuli. Based on this, we developed an exogenously excited bismuth-based heterojunction nanocatalyst Bi-Bi2O3–xSx-PEG (BOP) for the photocatalytic treatment of tumors with photothermal synergism. The high photocatalytic activity of BOP is attributed to its heterojunction structure, oxygen vacancy, and local surface plasmon resonance effect, which enable suitable band potential and rapid electron transfer. The GSH consumption characteristic of BOP in TME can also enhance oxidative stress damage, amplify the toxicity of ROS, and induce cell apoptosis. BOP's remarkable photothermal conversion ability contributes to local hyperthermia and synergistic enhancement of photodynamic efficacy. This platform provides a method for constructing an efficient photocatalyst and a strategy for synergistically enhancing photocatalytic therapy by thermal damage and oxidative stress.