Construction of a novel ESIPT and AIE-based fluorescent sensor for sequentially detecting Cu2+ and H2S in both living cells and zebrafish

The development of effective methods for tracking Cu2+ and H2S in living organisms is urgently required due to their vital function in a variety of pathophysiological processes. In this work, a new fluorescent sensor BDF with excited-state intramolecular proton transfer (ESIPT) and aggregation-induced emission (AIE) features for the successive detection of Cu2+ and H2S was constructed by introducing 3,5-bis(trifluoromethyl)phenylacetonitrile into the benzothiazole skeleton. BDF showed a fast, selective and sensitive fluorescence "turn off" response to Cu2+ in physiological media, and the situ-formed complex can serve as a fluorescence "turn on" sensor for highly selective detection of H2S through the Cu2+ displacement approach. In addition, the detection limits of BDF for Cu2+ and H2S were determined to be 0.05 and 1.95 μM, respectively. Encouraged by its favourable features, including strong red fluorescence from the AIE effect, large Stokes shift (285 nm), high anti-interference ability and good function at physiological pH as well as a low toxicity, BDF was successfully applied for the consequent imaging of Cu2+ and H2S in both living cells and zebrafish, making it an ideal candidate for detecting and imaging of Cu2+ and H2S in live systems.