We propose to synthesize new probes for the determination of intracellular glutathione and other cellular thiols. The reaction product of the probe with thiols will have longer wavelength absorption and emission and higher quantum yield than the best cytosolic thiol fluorophore currently in use for cell sorting by flow cytometry. The dye will have the advantage of being cell membrane permeable so that cell loading can occur at lower extra cellular dye concentrations than currently possible. The synthesized probes will be tested in vitro and in cell cultures for absorption and emission properties when bound to glutathione and other protein thiols. Cell toxicity will also be determined.
