A smart fluorescent probe for simultaneous detection of GSH and Cys in human plasma and cells

Abstract

Abnormal levels of glutathione (GSH) and cysteine (Cys) are associated with some diseases, thus monitoring the dynamic changes and the quantification of GSH/Cys is of great significance in clinical diagnosis. Herein, a smart fluorescent probe was developed for the detection of Cys and GSH, which was constructed with a far-red emitting indole-BODIPY and 7-nitrobenzofurazan (NBD) linked via an ether bond. Upon substitution of the ether with nucleophilic thiolate of GSH/Cys, the probe released indole-BODIPY fluorophore, which gave rise to a significant fluorescence “turn-on” signal at 635 nm. Moreover, Cys induced an intramolecular rearrangement reaction on electrophilic site of NBD, resulting in another emission band at 540 nm. Therefore, this probe can be used to simultaneously detect Cys and GSH in different emission channel. Such capability of the probe has been demonstrated for the measurement of Cys and GSH in human plasmas with fast response and low detection limit (0.64 μM). Furthermore, fluorescence imaging of HeLa cell indicated that the probe was cell membrane permeable and could be used for visualizing GSH and Cys in living cells.