Fabrication of an ultramicrosensor for measurement of extracellular myocardial superoxide

A novel superoxide (O₂^-) ultramicrosensor based on copper/platinum microparticles and electropolymerized pyrrole was fabricated for the measurement of extracellular myocardial superoxide. The Cu/Pt-PPy modified ultramicrosensors were evaluated, for the first time, as superoxide sensor. The amperometric response to superoxide was monitored at the potential of 0.45 V (versus saturated calomel electrode (SCE)) in Hank's balanced salt solution (HBSS). The sensor proved were proved to have a high sensitivity, selectivity and short response time. The detection limit is 24 (DL) of the sensors is 24 nmol/l (S/N of 3). The life period (at least 1 month) of sensors is longer than that of enzyme electrodes. The potential interference from some endogenous electroactive substances in biological tissues, such as hydrogen peroxide (H₂O₂), uric acid (UA), neurotransmitters and their metabolites, at the concentrations higher than those in biological systems, could be eliminated by further coating the Cu/Pt modified electrode with a polymer film. The method was applied to the measurement of superoxide production in a biologically relevant model system and in rat myocardial cells (MCs).