Glucose oxidase immobilized electrode for potentiometric estimation of glucose.

Glucose oxidase has been immobilized onto a thin platinum strip, by co-crosslinking with bovine serum albumin and glutaraldehyde. The retention of redox characteristics of glucose oxidase has been verified by cyclic voltammetry. The activity of the immobilized enzyme reduces to a quarter of its value when the enzyme is in solution but improves when coimmobilized with 1 M urea. The potentiometric response builds up and remains stable after 100 s. It is sensitive to the thickness of the immobilizing matrix. pH and temperature. An improvement in the performance of the electrode has been achieved by co-immobilizing 2 M urea and metal ions such as Mg2+ and Mn2+. The presence of Cu has been proved to be detrimental. The electrode has been calibrated in the 0.1-5.0 mM glucose concentration range. It gives a stable response for more than 50 independent assays and can be stored for 60 days without significant loss of function.