Stimuli‐Responsive Hybrid Vesicle for Tumor Dual‐Model NIR‐II Photoacoustic and Fluorescence Imaging and Precise Radiotherapy

Abstract Bioimaging guided‐radiotherapy is widely investigated as one of the mainstream cancer theranostic strategies for precision medicine. Nevertheless, background noise with “always‐on” imaging signal and inadequate tumor enrichment restrict disease diagnosis and therapy. Here, a nanogapped gold nanoparticles (AuNNPs)–silver sulfide (Ag₂S) vesicle (Ve) is designed as a “biological switch” through the self‐assembly of pH‐responsive polymer thiolated polystyrene‐co‐poly(4‐vinylpyridine) grafted AuNNPs and Ag₂S quantum dots (QDs). The AuNNPs–Ag₂S Ve exhibits quenched NIR‐II fluorescence (FL) and enhanced photoacoustic signals initially, which can be specifically activated by an acidic environment to release Ag₂S QDs and “turn on” NIR‐II FL signal in the second near‐infrared (NIR‐II, 950–1700 nm) window. Besides, the strategy of disease‐located NIR‐II imaging guided cancer therapy can remarkably enhance the therapeutic efficacy of radiotherapy, as well as minimize side effects. Such an intelligent nanoplatform with the ability of stimulus activated NIR‐II imaging guided radiotherapy shows great promise to precision biomedicine in the future.