Synthesis of a fluorescent probe based on rhodol's highly selective recognition of HS and its application in cells.

A new fluorescent probe for detecting hydrogen sulfide (HS) was developed through the thiolation reaction of 2-chloro-1,4-naphthoquinone. Rhodol was employed as the fluorophore, while 2-chloro-1,4-naphthoquinone acted as the reactive group for HS. The probe remains non-fluorescent under sunlight but emits a strong fluorescence upon reaction with HS, accompanied by a visible color change in the solution. This selective HS probe features rapid detection (under 1 minute), high photostability, and a very low detection limit (LOD = 44.3 nM), well below the levels that trigger physiological responses. The probe's mechanism was confirmed through H-NMR, HR-MS, and DFT analysis. With low cytotoxicity and high biocompatibility, the probe has been effectively applied for fluorescent bioimaging of HS in living cells.