A Naked-Eye Visible and Fluorescence

We demonstrate the utility of 4-chloro-7-nitrobenzofurazan (NBD-Cl), a simple, low-cost probe, for colorimetrically and fluorescently detecting and differentiating similar thiol species, including cysteine, homocysteine, and glutathione, as well as for assaying acetylcholinesterase (AChE) activity. This assay is a potential tool for investigating thiol functions in disease and diagnosis, and for screening AChE inhibitors. We envision that this versatile probe, which is commercially available and inexpensive, will be useful for further elucidating the roles of thiols in biology and also shows applicability for analysis of AChE inhibitors in physiological samples.