Two-Photon Fluorescent Probe for Detection of Exogenous and Endogenous Hydrogen Persulfide and Polysulfide in Living Organisms

Hydrogen persulfide and polysulfide (H2Sn) are newly discovered intracellular reactive species considered to have high protein S-sulfhydration efficiency. The detection of H2Sn in living systems is essential for studying their functions but is quite challenging. In this work, we report a two-photon excited fluorescent probe, QS(n), capable of tracking H2Sn in living organisms. QS(n) exhibited turn-on two-photon fluorescence response upon reaction with H2Sn. With a favorable photophysical property, high specificity, and low cytotoxicity, QS(n) was able to recognize exogenous H2Sn in living cells. More importantly, it realized for the first time the visualization of endogenous H2Sn generated in cells overexpressing cystathionine beta-synthase and cystathionine gamma-lyase, the enzymes responsible for producing endogenous H2Sn. Taking advantage of two-photon microscopy, the probe was also applied to achieve H2Sn detection in zebrafish embryos and to observe H2Sn distribution in living organisms.