Thiols are significant factors in many biological systems, and variations in cellular thiol levels have been associated with a number of disease states including psoriasis, cancer, and AIDS. For this reason, thiol probes that are fast, selective and sensitive are critical in the development of assays that hinge on thiol detection. Xi and co-workers⁽¹⁾ have reported on the properties and utility of the coumarin-maleimide as a thiol probe. They have shown that it (HC 9097) is water soluble, has efficient PET quenching, and offers significant turn-on fluorescence in the presence of GSH or cys. They show the Glutathione reductase probe to be highly selective for thiols over competing amino acids, and demonstrated the high sensitivity for low levels of thiols.

Ref:

1. Yi, L.; Li, H.; Sun, L.; Liu, L.; Zhang, C.; Xi, Z.Angew. Chem. Int. Ed. 2009, 48, 4034-4037.