Design of an ICT-based fluorescent probe with excellent sensitivity for visualizing GSH levels in live cells

Glutathione (GSH) is the most abundant mercaptan which is closely related to many clinical diseases in cells. In this study, we rationally designed a near-infrared fluorescent probe FOD to detect intracellular GSH based on the ICT mechanism. The structure of FOD was characterized by 1 H, 13 C NMR, FT-IR and HR-MS. FOD was constructed by using dicyanoisophorone as the push–pull fluorophore and 2, 4-dinitrobenzenesulfonyl moiety as the response group. Upon addition of GSH, FOD displayed noticeable color change from colorless to yellow with a sharp fluorescence enhancement (9.5-fold) at 586 nm and the absolute quantum yield of FOD increased to 4.6. Furthermore, FOD exhibited an excellent linear relationship with the concentration of GSH in the range of 0.2–1.8 μM and the detection limit of the probe was as low as 12.4 nM. FOD also can specifically toward GSH than other analytes. More importantly, FOD was successfully employed to detect endogenous GSH in living cells. Graphical abstract