Hydrogen Peroxide And B-nicotinamide Adenine Dinucleotide Sensing AmperometricElectrodes Based on Electrical Connection of Horseradish Peroxidase Redox Centers To Electrodes Through a Three-dimensional Electron Relaying Polymer Network

摘要

Hydrogen peroxide is efficiently electroreduced at an electrode modified with ahydrophilic, permeable film of horseradish peroxidase (HRP) covalently bound to a 3-dimensional epoxy network having polyvinyl pyridine (PVP)-complexed Os(bpy)2Cl+3/+2 redox centers. The sensitivity of the resulting H202 cathode at O.OV(SCE) is 1Acm(-2)M(-1). Its current increases linearly with H2O2 concentration in the 1x10(-7)M(-)2x10(-4)M range. Related NAD(P)H cathodes are based on stoichiometric homogeneous reduction of 02 to H202 by NADH or NAD(P)H. The reduction involves two known steps. In the first step, NAD(P)H transfers two electrons and a proton to a dissolved quinoid. The quinoids are typically derived of phenazines, however phenothiazine and phenoxazine derivatives are also useful. In the second step, two electrons and a proton are transferred from the reduced quinoid to O2. This reaction produces H202 and the original quinoid. Because the two reactions are quantitative, the sensitivity and the linear range of the resulting NADH and NADPH electrodes are identical with those of the H202 electrode, 1Acm(-2)M(-1) and 1x10(-7)M (-2)2x10(-4)M respectively.