A New Biosensor for Glucose Based on Carbon Paste and Enzyme Immobilized onto the Polyaniline Film

Conductive polymer polyaniline (PANI) was electrochemically synthesized by controlled potential cycling as a film at the surface of a carbon paste electrode (CPE) from acidic aqueous solution containing 1 M HCl and 0.25 M aniline. The characterization of the PANI-CPE was carried out with the aid of cyclic voltammetry in 1 M HCl, obtaining three couple of peaks from which the two pairs were distinct, having proved the electroactivity of the PANI film. Then, the PANI-CPE system was for the first time used and tested as glucose biosensor, when the respective enzyme was potentiostatically immobilized onto the surface from 0.1 M phosphate buffer (pH 7.5) with 0.75 mg/mL GOD. Optimal conditions for the enzyme immobilization were investigated and the biosensor tested for glucose sensing within the concentration range of 1-500 mgL-1 D-glucose. All preliminary assays with the GOD/PANI-CPE configuration have shown favorable operational features of this new carbon paste biosensor whose further development and adaptation for flowing streams are also outlined.