A highly sensitive amperometric glucose biosensor based on immobilizing glucose oxidase in electropolymerized poly(o-phenylenediamine) film on glassy carbon electrode coated sequentially with copper and palladium layers has been developed. The steady-state amperometric response to glucose was determined by means of the oxidation of hydrogen peroxide generated by the enzymatic reaction at a potential of either þ 0.70 or þ 0.40 V (vs. Ag j AgCl reference). The deposited copper/palladium layer showed great enhancement in the performance of the enzyme electrode, possibly due to its better electrocatalytic activity for hydrogen peroxide oxidation and large surface area. Effects of the relative loading of palladium, enzyme and polymer on the electrode performance were examined in detail. Sensitivity and detection limit for glucose determinations at þ 0.70 V were about 7.3 mA/mM and 0.1 mM, respectively. A wide linear range up to 6.0 mM glucose could be achieved. Electrode performance was superior to similar works reported in the literature. The response time was less than 2 s and its lifetime was longer than three months. The permeable polyphenylenediamine film also offered good anti-interference ability to ascorbic acid, uric acid and acetaminophen, especially when a detection potential of þ 0.40 V was employed.

Three phenylenediamine isomers (including ortho-, meta-and para-derivatives) were electrochemically polymerized to give polyphenylenediamine (PPD) films on platinized glassy carbon electrodes. Amperometric glucose sensors were developed by immobilizing glucose oxidase (GOx) into these polymer matrices during polymerization. Effects of the polymerization potential, polymerization charge, monomer concentration, GOx concentration and Pt deposition charge on the performance of the enzyme electrode to glucose were investigated. These resulting GC/Pt/PPD-GOx electrodes showed rapid electrochemical responses to hydrogen peroxide and glucose, and very good anti-interference ability to ascorbic acid. Correlation between the electroanalytical behaviors of the enzyme electrodes and the polymer structures was examined.