Synthesis of a fluorescent probe based on rhodol's highly selective recognition of H₂S and its application in cells

A new fluorescent probe for detecting hydrogen sulfide (H₂S) 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 H₂S. The probe remains non-fluorescent under sunlight but emits a strong fluorescence upon reaction with H₂S, accompanied by a visible color change in the solution. This selective H₂S 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 ¹H-NMR, HR-MS, and DFT analysis. With low cytotoxicity and high biocompatibility, the probe has been effectively applied for fluorescent bioimaging of H₂S in living cells.