Mitochondrial Specific H₂S_n Fluorogenic Probe for Live Cell Imaging by Rational Utilization of a Dual-Functional-Photocage Group

Reactive sulfur species play a very important role in modulating neural signal transmission. Hydrogen polysulfides (H₂S_n, n > 1) are recently suggested to be the actual signaling molecules. There are still few spatiotemporal controllable-based probes to detect H₂S_n. In this work, for the first time, we proposed the photocleavage product of the common photoremovable protecting group (2-nitrophenyl moiety) capable of trapping H₂S_n. Taking advantage of this, we constructed the probe H1 containing a photocontrollable group, a mitochondrial directing unit and a signal reporter fluorescein dye. H1 exhibited excellent fluorescence enhancement (50-fold) in response to H₂S_n under the aqueous buffer only after UV irradiation. H1 also showed high selectivity and sensitivity for H₂S_n over other reactive sulfur species, reactive oxygen species, and other analytes, especially biothoils including hydrogen sulfide, cysteine, homocysteine, and glutathione. We showed the utility of H1 to image H₂S_n in living cells with high spatiotemporal resolution.