ASSEMBLING AND EVALUATION OF NEW DEHYDROGENASE ENZYME ELECTRODE PROBES OBTAINED BY ELECTROPOLYMERIZATION OF AMINOBENZENE ISOMERS AND PQQ ONGOLD, PLATINUM AND CARBON ELECTRODES

Pt, Au and graphite electrodes have been coated by electropolymerizati on of 1,2-, 1,3-, 1,4-diaminobenzene (DAB) and 4-aminobiphenyl in the presence of pQQ using cyclic voltammetry. The activity of the modified electrodes for the oxidation of paracetamol, ascorbic and uric acid w as reduced by approximately 90% as compared to the bare electrodes. Po lymerization in the presence oxo-1H-pyrrolo(2,3-f)quinoline-2,7,9-tric arboxilic acid, pyrroloquinolinequinone (pQQ) led, after optimization, to electrodes capable of catalysing the electroxidation of beta-nicot inamide adenine dinucleotide, reduced form (NADH), in the range 10(-4) -10(-2) mol/l with a detection limit of 5 x 10(-5) mol/l. Amperometric measurements of NADH have been carried out at + 0 . 2 V and the effic iency of different electrodes based on different materials has been st udied. By co-entrapment of dehydrogenase highly selective enzymes, ele ctrodes for glucose, L-lactate and L-glutamate were obtained. Dehydrog enase substrates such as glucose, lactate and glutamate were measured in the range 5 x 10(-5)- x 10(-2) mol/l, with detection limits of 10(- 5) and 5 x 10(-6) mol/l, respectively. Probe stability under non-dynam ic conditions was evaluated over 2 months. All the probes showed a dec rease of 10% over 1 month and a residual activity of 50% over 2 months . (C) 1997 Elsevier Science Limited.