A rhodium-modified amperometric biosensor based on the recently introduced ceramic-carbon composite electrode has been developed. The sensors are comprised of Rh metal and glucose-oxidase-modified graphite particles embedded in a porous, organically modified silicate network. The hydrophobicity of the matrix imparts limited wettability. The thickness of the active layer of the electrode can be tuned by incorporating hydrophilic components such as metal particles and proteins. This layer can be removed by mechanical polishing to reveal a fresh uncontaminated reactive layer. In the present construction, rhodium is used for electroreduction of the biochemical reaction product, hydrogen peroxide. The continuous supply of oxygen from the top of the electrode through the porous structure facilitates operation even in oxygen-free solutions, in a gas diffusion/biosensing mode of operation. Operation in clinical blood plasma shows that the electrode can be used conveniently for analysis of biological samples. The sensor can be used at very low overpotentials and is free of common interferences, such as ascorbic acid, acetaminophen, uric acid, urea and salicylic acid. It is found to be stable over long periods.
Bibliographical noteFunding Information:
Financial support by the Gesellschaft fuer Biotechnolo-gische Forschung-GBF is gratefully acknowledged.
- Membrane-free sensor
- Methyl silicate
- Porous network