Detection of uric acid with a new type of conducting polymer-based enzymatic sensor by bipotentiostatic technique

A new type of electronically conducting polymer-based uric acid sensor was constructed by using dodecyl sulfate doped poly(N-methylpyrrole) for enzyme immobilization. The results proved that this polymer film could incorporate the enzyme during its electrochemical preparation assumingly owing to the electrostatic interaction between the oxidized layer and the basic form of the enzyme. The lay-out prepared by thick film technology was designed for bipotentiostatic measurements, where the two working electrodes with and without the enzyme were analogously polarized. The currents in the two circuits were measured in parallel, and the current difference was connected to the 'net' current originating from the enzymatic reaction. The detection procedure was studied at different pH and potential values, and the calibration curve was determined under optimal circumstances, where the signal of the sensor increased in the physiologically important range. The kinetic range was used for the determination of the Michaelis parameters. Preliminary studies on the effects of the temperature and potentially interfering substances such as glucose or ascorbic acid are also discussed. (C) 1999 Elsevier Science B.V. All rights reserved.