Electrochemical sensor for simultaneous detection of ascorbic acid, uric acid and xanthine based on the surface enhancement effect of mesoporous silica

The measurement of ascorbic acid (AA), uric acid (UA) and xanthine (XA) is very important in the clinical diagnosis because many diseases have been found to be associated with their concentrations. Herein, an electrochemical sensor using mesoporous SiO2 as sensing material was firstly developed for the simultaneous detection of AA, UA and XA. With distinctive properties such as uniform porous networks, large surface area and high sorption ability, the mesoporous SiO2 sensor exhibits remarkable surface enhancement effect, and greatly increases the response signals of AA, UA and XA. In addition, the electrochemical responses of coexistence of AA, UA and XA were studied, and three well-shaped oxidation peaks were observed at 0.00, 0.25 and 0.63 V. Further studies suggest that their oxidation takes place independently and has no mutual interference. This sensor possesses high sensitivity, and the limit of detections are 3.0 x 10(-6) mol L-1, 1.0 x 10(-7) mol L-1 and 7.5 x 10(-7) mol L-1 for AA, UA and XA. Finally, the mesoporous SiO2 sensor was successfully employed to detect AA, UA and XA in the urine and blood serum samples. (C) 2009 Elsevier B.V. All rights reserved.