A high-valence bismuth(V) nanoplatform triggers cancer cell death and anti-tumor immune responses with exogenous excitation-free endogenous HO- and O-independent ROS generation.

Reactive oxygen species with evoked immunotherapy holds tremendous promise for cancer treatment but has limitations due to its dependence on exogenous excitation and/or endogenous HO and O. Here we report a versatile oxidizing pentavalent bismuth(V) nanoplatform (NaBiO-PEG) can generate reactive oxygen species in an excitation-free and HO- and O-independent manner. Upon exposure to the tumor microenvironment, NaBiO-PEG undergoes continuous H-accelerated hydrolysis with •OH and O generation through electron transfer-mediated Bi-to-Bi conversion and lattice oxygen transformation. The simultaneous release of sodium counterions after endocytosis triggers caspase-1-mediated pyroptosis. NaBiO-PEG intratumorally administered initiates robust therapeutic efficacies against both primary and distant tumors and activates systemic immune responses to combat tumor metastasis. NaBiO-PEG intravenously administered can efficiently accumulate at the tumor site for further real-time computed tomography monitoring, immunotherapy, or alternative synergistic immune-radiotherapy. Overall, this work offers a nanomedicine based on high-valence bismuth(V) nanoplatform and underscores its great potential for cancer immunotherapy.