An Enzymatic Clay-Modified Electrode for Aerobic Glucose Monitoring with Dopamine as Mediator

Considering the unique adsorption and regeneration properties of dopamine, glucose oxidase, and nontronite, a glucose sensor was constructed by immobilizing glucose oxidase and nontronite clay coating on a glassy carbon electode with dopamine as mediator. The response of the glucose sensor was determined by measuring the cyclic voltammetric oxidation peak current values of dopamine under aerobic solution conditions. The effects of the amount of enzyme immobilized, the operating pH, and the common interferences on the response of the glucose sensor were studied. The detection limit was 7.4 μM (S/N = 3), with a linear range extending to about 10 mM, giving a dynamic range of about 3 orders of magnitude for 0.8 mM dopamine. When stored in pH 7 phosphate buffer at 4 °C, the sensor shows almost no change in performance after operating for 45 days.