Electrochemical glucose biosensor with improved performance based on the use of glucose oxidase and Prussian Blue incorporated into a thin film of self-polymerized dopamine

We report on the use of self-polymerized dopamine (PDA) in an enzyme-based biosensor with improved performance. This is due to the fact that poly-DA strongly improves the stability of the electrocatalyst Prussian Blue (PB) in neutral and alkaline solution. The polymer also effectively entraps the enzyme glucose oxidase (GOx) while retaining its activity. A glucose biosensor was fabricated by modifying a glassy carbon electrode with a thin film of PB into which GOx was incorporated with the assistance of PDA film. The PB films enable a facile electrochemical reduction, and thus the determination, of enzymatically generated H2O2 at a remarkably low potential of 0.0 V (versus Ag/AgCl). The biosensor responds linearly to glucose in the 200 μM to 3.4 mM concentration range, with a sensitivity of 1.59 nA μM−1, a 46.2 μM detection limit, a response time of 15 s, and with storage stabilities of 3 months at 4–8 °C and of >4 weeks at room temperature. The biosensor is highly selective over many other electroactive species, reproducible, and stable even at weakly alkaline pH values. The stabilized PB films by PDA will widen horizons of its applications both as H2O2 sensor and for elaboration of the oxidase-based biosensors in physiological environment.