Developing a styrylpyridinium-based fluorescent probe with excellent sensitivity for visualizing basal H2S levels in mitochondria

Hydrogen sulfide (H2S) is recognized as a critical gaseous signaling molecule involved in multiple physiological and pathological processes. The important pathophysiological roles of H2S have spurred intense interest in developing fluorescent probes for imaging of H2S. Using a piperazidine-bridged styrylpyridinium as the push-pull fluorophore and a 7-nitro-1,2,3-benzoxadiazole moiety as the response group, herein we developed a mitochondria-targeted fluorescent probe MNOP-H2S, which exhibited remarkable fluorescence turn-on (>130 fold), large Stokes shift (190 nm), excellent sensitivity and selectivity. Importantly, the probe was characterized by an ultralow detection limit (29 nM), thereby being successfully applied to monitor mitochondrial basal H2S levels in various types of cells and zebrafish, to distinguish cancer cells from normal cells (even from each other) and to reveal that the endogenously produced H2S in mitochondria is a key mediator for the endothelial cell migration stimulated by vascular endothelial growth factor.