A fluorescent probe for differentiating Cys, Hcy and GSH via a stepwise interaction

It is still challenging to simultaneously distinguish general biothiols (cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) etc.) in complex redox environments, due to the lack of reliable and convenient method. Although a number of fluorescence and/or UV–vis absorption based measurements have been employed for single or multiple biothiols detection, few of them is capable of recognizing each biothiol with individual signal at the same time. We present a one-step obtained selenadiazole derivative (1) to distinguish Cys, Hcy and GSH, which not only can produce three new kind of fluorescent compounds, but also simultaneously induce different “turn-on” fluorescence emission and red-shifted absorption signals for discriminating each biothiol. With a series of systematically analyses elucidate that probe 1 possesses high sensitivity and good selectivity for the three biothiols. Furthermore, the detection mechanism was also verified via a stepwise selenium–nitrogen (Se–N) bond cleavage process of probe 1 interacting with each biothiol. In the application of tracking in vitro and in vivo biothiols, probe 1 can be acted as a dual-mode fluorescent and colorimetric platform.