A new biotin derivative functionalized by an electropolymerizable pyrrole group has been synthesized. The electrooxidation of this biotin pyrrole has allowed the formation of biotinylated conducting polypyrrole films in organic electrolyte. Gravimetric measurements based on a quartz crystal microbalance, modified by the biotinylated polymer, revealed an avidin-biotin-specific binding at the interface of polymer-solution. The estimated mass increase corresponded to the anchoring of 1.5 avidin monolayers on the polypyrrole surface. In addition, the subsequent grafting of biotinylated glucose oxidase was corroborated by electrochemical permeation studies. Enzyme multilayers composed of glucose oxidase or polyphenol oxidase were elaborated on the electrode surface modified by the biotinylated polypyrrole film. The amperometric response of the resulting biosensors to glucose or catechol has been studied at +0.6 or -0.2 V vs SCE, respectively.

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A novel catalytic material (mesoporous TiOz films) for the cathodic detection of hydrogen peroxide in air-saturated aqueous solution is described. The immobilization of glucose oxidase (GOD) as enzyme model onto the TiOz electrode provides an efficient biosensor for the arnperometric detection of glucose at -0.15 V (vs. SCE). GOD molecules were immobilized in an inorganic laponite gel and cross-linked by glutaraldehyde. The highest sensitivity and detection limit were 3.33 mA M-' cm-' and 15 pM, respectively. In addition different procedures of enzyme immobilization including cross-linking with glutaraldehyde and physical entrapment in a functionalized polypyrrole film have been compared.

A photoreactive organic polymer was prepared by oxidative electrochemical polymerization of a pyrrole-benzophenone derivative on conductive surfaces; the resulting polypyrrolic film allowed, upon irradiation, the reagentless covalent grafting of proteins.

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