An Amperometric Biosensor for Uric Acid Determination Prepared from Uricase Immobilized in Polypyrrole Film

Abstract

In order to prepare a biosensor for the determination of uric acid, electropolymerization of pyrrole on Pt surface was carried out with an electrochemical cell containing pyrrole, ferrocene (as a electron mediator) and tetrabutylammonium tetrafluoroborat in acetonitrile by cyclic voltammetry between 0.0 and 1.0 V (vs. Ag/AgCl) at a scan rate of 50 mV/s upon Pt electrode. Uricase was immobilized by a glutaraldehyde/gelatine croslinking procedure on to polypyrrole film after the electropolymerization processes. The response of the biosensor against uric acid was measured after 330 seconds following the application of a constant potential of +0.7 V (vs. Ag/AgCl). The resulting biosensor exhibits excellent electrocatalysis for the uric acid. The amperometric determination is based on the electrochemical detection of H₂O₂, which is generated in enzymatic reaction of uric acid. The sensor responds to uric acid with a detection limit of 5.0 × 10⁻⁷ M. The sensor remains relatively stable for 5 weeks. Interference effect were investigated on the amperometric response of the biosensor. Determination of uric acid was carried out in the biological fluids by biosensor.

Keywords:

• Uric acid biosensor
• Amperometry
• Polypyrrole
• Ferrocene
• Biological fluids
• Interferences