Entrapment of enzymes in electropolymers for biosensors and graphite felt based flow-through enzyme reactors

Immobilization of glucose oxidase in conducting polymers electrochemically generated from pyrrole, N-methylpyrrole, aniline and orthophenylene diamine on platinum surfaces was used to construct amperometric glucose biosensors. High sensitivity was obtained with a sensor utilizing polymerized o-phenylene diamine as entrapment matrix. This polymer, as well as polypyrrole, was used to prepare a new type of enzyme reactors with immobilized glucose or lactate oxidase by depositing enzyme-polymer layers on pieces of graphite felt. Mounted into a column, the felt can then be applied as an enzyme reactor in a flow system. It can either be used as working electrode itself in an electrochemical detection system or be combined with a separate detector. A microelectrode array was chosen as an example of the latter. With this system, detection limits lower than 500 mu M and a linear range up to 10 mM were obtained for glucose and a detection limit lower than 50 mu M and a linear range up to 1 mM for lactate, respectively.