Enzymatic Product-Mediated Stabilization of CdS Quantum Dots Produced In Situ: Application for Detection of Reduced Glutathione, NADPH, and Glutathione Reductase Activity

Glutathione is the most abundant nonprotein Molecule in the cell and plays an important role in many biological processes, including the maintenance of intracellular redox states, detoxification, and metabolism. Furthermore, glutathione levels have been linked, to several human diseases, such as AIDS, Alzheimer disease, alcoholic liver disease, cardiovascular disease, diabetes mellitus, and cancer. A novel concept in bioanalysis, is introduced and applied to the highly sensitive and inexpensive detection of. reduced glutathione (GSH) over its oxidized form (GSSG) and glutathion. reductase (GR) in human serum. This new fluorogenic bioanalytical System is based on the GSH-mdiated stabilization of growing CdS nanoparticles. The sensitivity of this new assay is 5 pM of GR, which is 3 orders,of magnitude better than other fluorogenic methods previously reported.