A red-emission probe for intracellular biothiols imaging with a large Stokes shift

Small molecule biothiols, including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), play important roles in physiological and pathological processes, which are related to many diseases. Hence the detection of cellular biothiols is of great significance. Here we reported a new probe DNT that was constructed by a donor acceptor type dye NT-OH and a recognition site DNBS group. DNBS group also acted as a fluorescence quencher in this molecule. While in the presence of biothiols, the DNBS group reacted with the sulfydryl group of thiols by nucleophilic aromatic substitution reaction and then eliminated from the probe, turning on the red fluorescence of the probe with emission maxima at 640 nm and a large Stokes shift of 160 nm. Solution experiments revealed that DNT showed high sensitivity and selectivity to biothiols. Besides, it was further utilized to map endogenous biothiols in MCF-7 cells successfully.