Dual-emission fluorescent probe for discriminative sensing of biothiols

Herein, a dual-emission fluorescent probe (RED-NBD) for discriminative detection of cysteine/homocysteine (Cys/Hcy) and glutathione (GSH) was reported. Probe RED-NBD was prepared by conjugating a new red-emissive fluorophore (RED) with nitrobenzofurazan moiety (NBD). Upon reacting with Cys/Hcy, RED-NBD can be cleaved into fluorophore RED and NBD-Cys/Hcy, which can display distinct red and green fluorescence under a single-wavelength excitation, respectively. While the reaction between RED-NBD with GSH generates the red-emissive NBD and nonfluorescent NBD-SH. Thus, the RED-NBD can differentiate Cys/Hcy from GSH and realize the sensitive detection of these biothiols with low detection limits. Additionally, RED-NBD has also been used for discriminative visualizing of Cys/Hcy and GSH in cells.