Controlled Fabrication of Glucose and Catechol Microbiosensors via Electropolymerized Biotinylated Polypyrrole Films

The functionalization of microelectrodes has been carried out by oxidative polymerization of a biotinyl pyrrole monomer in acetonitrile. The resulting biotinylated polymer was used for the simple and reagentless anchoring of avidin and biotinylated enzymes via avidin-biotin bridges. Thus, the immobilization of five layers of glucose oxidase was performed on various platinum electrodes (surfaces: 0.165 and 0.448 mm2). The amperometric response of the microbiosensors to glucose was recorded at 0.6 V vs Ag/AgCl and the analytical performances (sensitivity and I max) were proportional to the microelectrode surface. In addition, the immobilization of four and seven layers of polyphenol oxidase on carbon fiber microelectrodes (diameter 8 μm) has led to amperometric biosensors for catechol exhibiting analytical characteristics proportional to the number of enzyme layers. Moreover, these two kinds of microbiosensor present apparent K M values similar to those determined for the free enzymes in bulk solution.