ACTIVITY OF FREE AND IMMOBILIZED GLUCOSE-OXIDASE - AN ELECTROCHEMICALSTUDY

The activity of free and immobilized glucose oxidase was determined us ing a sandwich type thin-layer electrochemical cell. The thin-layer ce ll consisted of a gold electrode deposited on a glass microscope slide , 165 mum thick Teflon TFE spacers, and a glass cover. Enzyme activity was determined by using cyclic voltammetry to measure the amount of h ydrogen peroxide produced in the glucose oxidase catalyzed redox react ion between glucose and oxygen in the thin-layer cell. The specific ac tivity of 13.4 nM glucose oxidase in 0.2 M aqueous sodium phosphate, p H 5.2 at room temperature, was calculated to be 4.34 U/mg GOx. Under t he same experimental conditions, qualitative detection of the activity of glucose oxidase covalently immobilized to a thin radiofrequency pl asma modified poly(etherurethaneurea) film was demonstrated.