Rapid, Photoinduced Electron Transfer-Modulated, Turn-on Fluorescent Probe for Detection and Cellular Imaging of Biologically Significant Thiols

[Image: see text] There is a very limited number of existing probes whose fluorescence is turned on in the presence of the class of biological thiols made up of glutathione, cysteine, and homocysteine. The extant probes for this class of biological thiols commonly have poor aqueous solubility and long analyte response times, and they demand a very high probe/thiol ratio for decreased time of significant reporter signal generation; knowledge regarding their selectivity with respect to other sulfur-based analytes is unclear. Described here is a previously unreported photoinduced electron-transfer-quenched probe (HMBQ-Nap 1) that offers highly selective and rapid in vitro detection of this class of biologically important thiols at low concentrations and low probe/thiol ratio, and importantly, very rapid imaging of these biological thiols in human cells.