Sol-gel derived composite materials for the construction of oxidase/peroxidase mediatorless biosensors

A new bienzymatic electrode for glucose sensing has been constructed with the aid of the sol-gel process. This mediatorless sensor was made by the simultaneous immobilization of graphite microparticles and two enzymes (horseradish peroxidase (HRP) and glucose oxidase (GOD)) in a silica gel matrix. The amperometric detection of glucose was assayed by potentiostating the biosensor at 0 V vs SCE in order to reduce the enzymically generated H2O2. The active graphite particles evenly dispersed within the silica gel matrix establish an efficient electrical communication between the electrode surface and the HRP active center. The effect of graphite and HRP amounts have been investigated in order to improve the analytical characteristics of the amperometric H2O2 biosensor. For determination of glucose, a bilayer structure where HRP and GOD were immobilized in two separated silica films exhibited the higher analytical performances.