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 Imax) 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 KM values similar to those determined for the free enzymes in bulk solution.