This paper reviews our work on the application of amperometric electrochemical systems as enzyme biosensors. After a brief review of the different configurations generally described in the literature for such electrochemical enzyme sensors, we focus more specifically on reagentless biosensors. Two enzymes are considered: pyruvate oxidase, and lactate oxidase, which have numerous potential applications and share the same flavin adenine dinucleotide redox-active group. These enzymes are covalently immobilized on an original conducting copolymer, poly(5-hydroxy-1,4-naphthoquinone-co-5-hydroxy-3-thioacetic acid-1,4-naphthoquinone). This film is able to recycle these enzymes efficiently under anaerobic or aerobic conditions, at very low working potentials, starting from -0.1 V vs. SCE. This is the lowest working potential ever described for these enzymes. This prevents side-oxidation of the most common interfering species, e.g. ascorbic acid.
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