Integrated electrically contacted glucose oxidase/carbon nanotube electrodes for the bioelectrocatalyzed detection of glucose

Carbon nanotubes (CNTs) are coated with polyethylene imine (PEI) or poly(acrylic acid) (PAA). The polymer-functionalized CNTs were deposited on glassy carbon electrodes and provided a support for the covalent binding of ferrocene derivatives 1 or 2 on the PEI or PAA polymers, respectively, and for the covalent association of the enzyme, glucose oxidase, on the polymers. The resulting integrated CNTs/ferrocene/enzyme assemblies exhibited electrical contact with the glassy carbon electrode. The systems were implemented for the bioelectrocatalyzed oxidation of glucose and for the development of amperometric glucose sensors. We demonstrate that the CNTs contribute to the effective bioelectrocatalyzed oxidation of glucose by the CNTs/ ferrocene/enzyme systems by providing high surface areas for the immobilization of the relay/enzyme unit and by providing enhanced charge transport between the enzyme redox center and the electrode that improve the electrical contacting efficiency.