Typically, enzymes are immobilized in inorganic, sol-gel, or polymeric matrices for applications in enzyme-based biosensors. In this report, the feasibility of using immunoglobulin (IgG) as an immobilization matrix for glucose oxidase (GO) was investigated. The effects of binding GO to IgG on its enzymatic activity and kinetics were studied using cyclic voltammetry and scanning electrochemical microscopy. These studies indicated a comparatively small reduction in the enzyme-mediator reaction rate when the GO enzyme was bound to IgG, against other immobilization methods. The turnover numbers for IgG-bound GO adsorbed on gold and glass substrates were 475-740 and 103-354 s(-1), respectively, using ferrocenemethanol as a mediator. Finally, the suitability of the IgG-based immobilization method to entrap GO on the electrode surface was demonstrated in an amperometric glucose biosensor fabricated using physically adsorbed IgG-bound GO immunocomplex on a gold electrode. (C) 2008 The Electrochemical Society.