An ESIPT-based fluorescent probe with fast-response for detection of hydrogen sulfide in mitochondria

Excited-state intramolecular proton transfer (ESIPT) has recently received considerable attention due to its dual fluorescent changes and large Stokes shift. Hydrogen sulfide (H2S) is a gas signal molecule that plays important roles in modulating the functions of different systems. Herein, by modifying 2-(2́-hydroxyphenyl) benzothiazole (HBT) scaffold, a novel near-infrared mitochondria-targeted fluorescent probe HBTP-H2S has been rationally designed based on excited-state intramolecular proton transfer (ESIPT) effect. The nucleophilic addition reaction of the H2S with probe HBTP-H2S caused the break of the conjugated skeleton, resulting the shifting of maximum emission peak from 658 nm to 470 nm. HBTP-H2S showed fast-response response time, good selectivity and a large Stokes shift (188 nm) toward H2S. Most importantly, inspired by the inherent advantages of the probe, HBTP-H2S was successfully employed to monitor mitochondrial H2S in HepG2 cells.