Preparing a new biosensor for hypoxanthine determination by immobilization of xanthine oxidase and uricase in polypyrrole-polyvinyl sulphonate film.

In this study, a new amperometric biosensor for the determination of hypoxanthine was developed. To this aim, polypyrrole-polyvinyl sulphonate films were prepared on the platinum electrode by the electropolymerization of pyrrole in the presence of polyvinyl sulphonate. Xanthine oxidase and uricase enzymes were immobilized in polypyrrole-polyvinyl sulphonate via the entrapment method. Optimum conditions of enzyme electrode were determined. Hypoxanthine detection is based on the oxidation of hydrogen peroxide at +400 mV produced by the enzymatic reaction on the enzyme electrode surface. The linear working range of biosensor for hypoxanthine was determined. The effects of pH and temperature on the response of the hypoxanthine biosensor were investigated. Optimum pH and temperature were measured as 8 and 30°C, respectively. Operational and storage stability of the biosensor were determined. After 20 assays, the biosensor sustained 74.5% of its initial performance. After 33 days, the biosensor lost 36% of its initial performance. The performance of the biosensor was tested in real samples.