Recent progress on the development of glutathione (GSH) selective fluorescent and colorimetric probes

Glutathione (GSH) plays a key role in many cellular functions. Abnormal levels of GSH is considered to be sign of many diseases. As a result, various fluorescent imaging probes and/or chemosensors for GSH have been developed. Compared to other analytical methods, fluorescence has unique merits, such as excellent detection limits and sensitivity for use in imaging cells, tissues and small animals. However, colorimetric probes undergo distinct color changes, which in most cases can be detected by using the naked eye. This review of studies aimed at the development of GSH probes is presented in a format that is organized by structural features and chemical reactions of the probes. The topics include probes that are based on nanoparticles or nanocomposites, metal ion displacement and coordination and chemical reactions. The reaction based probes are further classified into probes that undergo cleavage of sulphonamide, sulfonate ester and related functional groups, SeN bond cleavage, aryl substitution reactions, disulfide bond cleavage followed by cyclization, Michael additions, and other processes.