Two chemodosimeters for fluorescence recognition of biothiols in aqueous solution and their bioimaging application

Two fluorescein derivatives containing 2,4-dinitrobenzenesulfonyl group have been developed as fluorescent probes to detect the biothiols (Cys, Hcy and GSH) in aqueous solution. Probes 1 and 2 can distinguish these biothiols in the presence of other amino acids. While probe 1 can recognize the biothiols in PBS/DMSO (v:v = 95:5, pH = 7.40) solution, notably probe 2 could be used in PBS buffer solution (pH = 7.40). The detection limit of Cys for probe 2 reached at 0.021 μM in aqueous solution, which was lower than the intracellular concentration of Cys. In the recognition process, a reaction between the probes and the biothiols occurred, in which the S–O bond was cleaved to remove 2, 4-dinitrobenzenesulfonyl group. The data of 1H NMR, MS and DFT/TD-DFT calculation further confirmed the detection mechanism. Moreover, two probes were successfully applied to the HeLa cell imaging. [Display omitted] •Preparation of water-soluble fluorescence probes.•Probe 2 could be used in PBS buffer solution (pH = 7.40) for the detection of biothiols over other amino acids.•The significant turn-on fluorescence responses were obtained by using 491 nm as excited wavelength.•Good performance on living cell imaging.