In vivo detection of glutathione disulfide and oxidative stress monitoring using a biosensor

A highly sensitive in vivo biosensor for glutathione disulfide (GSSG) is developed using covalently immobilized-glutathione reductase (GR) and -beta-nicotinamide adenine dinucleotide phosphate (NADPH) on gold nanoparticles deposited on poly[2,2':5',2 ''-terthiophene-3'-(p-benzoic acid)] (polyTTBA). The fabricated biosensor was characterized with SEM, TEM, XPS, and QCM. Analytical parameters affecting the biosensor performance were optimized in terms of applied potential, NADPH:GR ratio, temperature, and pH. A linear calibration plot is obtained using chronoamperometry in the dynamic range between 0.1 mu M and 2.5 mM of GSSG, with a detection limit of 12.5 +/- 0.5 nM. The developed biosensor is applied to detect GSSG in a real plasma sample. A microbiosensor was applied to detect the in vivo GSSG concentration to monitor the oxidative stress caused by diquat and t-butyl hydroperoxide. The results obtained are reliable, implying a promising approach for a GSSG biosensor in clinical diagnostics and oxidative stress monitoring. (C) 2011 Elsevier Ltd. All rights reserved.