Rational development of an ESIPT-based fluorescent probe with large Stokes shift for imaging of hydrogen sulfide in...

It is crucial to monitor hydrogen sulfide (H₂S) because H₂S plays a vital role in the regulation of many physiology and pathology processes. Many evidences indicate that endogenous H₂S is closely associated with many diseases such as inflammation and cancers. Herein, we reported a novel fluorescent probe BTDI to monitor the fluctuation of H₂S based on the excited-state intramolecular proton transfer (ESIPT) mechanism both ex vivo and in vivo. The selectivity of BTDI for H₂S is significantly higher than that for biothiols and other potential anions. After the probe responded to H₂S, the nucleophilic addition reaction of the H₂S with probe BTDI resulted the shifting of maximum emission peak from 630 nm to 542 nm and the fluorescent signals change from red to green emission along with a large Stokes shift (240 nm). Moreover, BTDI can be successfully applied to detect extracellular and endogenous H₂S in living cells through fluorescent cell-imaging, which provides a promising tool for the specific recognition of H₂S in complex biological systems.