CBS and neoplasm: More importantly, this probe could serve as a promising tool for the direct photoacoustic imaging of endogenous H2S generation in a HCT116 tumor-bearing mouse model, verifying the activating effect of CBS upregulation on the elevated level of H2S. To the best of our knowledge, this work represents the first example of NIR-activatable photoacoustic probes capable of reporting the endogenous production of H2S in real time, which may facilitate further exploration of the complex roles of H2S in living systems.