Renewable, reagentless glucose sensor based on a redox modified enzyme and carbon-silica composite

A new type of sol-gel derived, ferrocene derivatized glucose oxidase based amperometric biosensor is introduced. The electrode consists of graphite powder impregnated with a ferrocene modified enzyme imbedded in an organically modified silicate network. In this assembly, graphite powder provides percolation conductivity, the organic modification of the silicate ensures that the whole bulk of the material is not wetted by the analyte, thus providing a thin reactive layer. The ferrocene which is covalently attached to the enzyme acts as a mediator for the enzymatic reaction, thereby communicating with the conducting graphite in the matrix. The electrode can be reproducibly renewed by mechanical polishing. Thick film biosensors, where a drop of the analyte is sufficient for the sensing process is also demonstrated with this material.