An amperometric biosensor for fish freshness detection from xanthine oxidase immobilized in polypyrrole-polyvinylsulphonate film

Abstract

A new amperometric biosensor was developed for determining hypoxanthine in fish meat. Xanthine oxidase with pyrrole and polyvinylsulphonate was immobilized on the surface of a platinum electrode by electropolymerization. The determination of xanthine-hypoxanthine was performed by means of oxidation of uric acid liberated during the enzyme reaction on the surface of the enzyme electrode at + 0.30V (SCE). The effects of pH, substrate concentration, and temperature on the response of the xanthine-hypoxanthine biosensor were investigated. The linear working range of the enzyme electrode was 1.0 × 10⁻⁷ –1.0 × 10⁻³ M of the hypoxanthine concentration, and the detection limit was 1.0 × 10⁻⁷M. The apparent K_m(app) and I_max of the immobilized xanthine oxidase were found to be 0.0154 mM and 1.203 μA/mM, respectively. The best pH and temperature value for xanthine oxidase were selected as 7.75 and 25°C, respectively. The sensor was used for the determination of hypoxhantine in fish meat. Results show that the fish degraded very rapidly after seven days and the hypoxanthine amount was found to increase over days of storage.

Keywords::

• Xanthine
• hypoxanthine
• biosensor
• xanthine oxidase
• polypyrrole–polyvinylsulphonate
• fish freshness
• methylene blue

Acknowledgments

We acknowledge the support of this project by Gazi University Research Fund (FEF 05/2009-23).

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.