Electrosynthesis and Characterization of Composite Polypyrrole-Dextran-Sulfite Oxidase Films

The electrosynthesis of a composite polypyrrole-dextran-sulphite oxidase (PPy-Dex-SOx) film was carried out by galvanostatic polymerisation. The simultaneous formation of a conducting polypyrrole support and the entrapment of sulfite oxidase (SOx) on a platinum electrode was accomplished in an aqueous solution which contained 0.5 M pyrrole, 0.02 g/1 dextran and 8 units/ml SOx at an applied current density of 0.25 mA/cm2 and a polymerization time of 25 sec. The conductivity of the resulting composite PPy-Dex-SOx film was as high as that of polypyrrole- sulfite oxidase (PPy-SOx) film, but the presence of dextran improved the mechanical stability of the composite film. The presence of SOx in the composite film was confirmed by scanning electron microscopy and arnperometric measurement of sulfite.