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

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.