A glucose oxidase electrode based on electropolymerized conducting polymerwith polyanion-enzyme conjugated dopant

An enzyme immobilization method has been developed by electropolymerization chemistry of conducting polymer which results in a more effective and repr oducible enzyme electrode. As a model system, in this study, glucose oxidas e (GOD) was conjugated with a polyanion, poly(2-acrylamido-2-methylpropane sulfonic acid), via a poly(ethylene oxide) spacer to improve the efficiency of enzyme immobilization into a conducting polymer. GOD was successfully c onjugated with a high conjugation yield of more than 90%, and its bioactivi ty was preserved. The resulting polyanion-GOD conjugate was used as a dopan t for the electrochemical polymerization of pyrrole, Polypyrrole was effect ively deposited on a Pt wire working electrode with the polyanion-GOD conju gate. The enzyme electrode responded to glucose concentrations of up to 20 mM with a sensitivity of 40 nA/mM at an applied potential of 0.4 V within a response time of 30 s. Although the response signal decreased at the low a pplied potential of 0.3 V, the enzyme electrode showed sensitive response s ignals of about 16 nA/mM up to 20 mM in glucose concentration. Under the de oxygenated condition, reduced but clear response current signal was obtaine d. The results show that the current signal response of the enzyme electrod e to glucose concentration may be produced by mixed mechanisms.