Abstract

The aim of this work is the development of a biosensor to determine uric acid on serum. The biosensor has been developed through enzymatic immobilization of uricase from Candida spp. and peroxidase from horseradish on mesoporous silica with hexagonal symmetry (MCM-41). The mesoporous material was immobilized by Nafion assisted adsorption on a glassy carbon electrode, which was used as working electrode. Measurements were performed in a conventional three electrodes cell. The biosensor configuration allowed a fast, sensitive and stable electrochemical detection of hydrogen peroxide generated by the enzyme reaction. All experimental variables involved in the preparation and performance of the enzyme biosensor were optimized. Amperometry in stirred solutions at -100 mV provided a linear calibration plot for uric acid in the 2-10 mu M concentration range. Furthermore, the proposed biosensor showed excellent analytical performance with detection and quantification limits of 0.33 mu M and 2 mu M, respectively; analytical sensitivity of 3.908 nA mu M-1, repeatability <2.11% and a long-term stability of 14 days (daily measurements). The biosensor yielded good results in the determination of uric acid in spiked human serum samples. (C) 2014 Elsevier B.V. All rights reserved.