CLAY-ENHANCED ELECTROCHEMILUMINESCENCE AND ITS APPLICATION IN THE DETECTION OF GLUCOSE

Clay-modified electrodes were prepared with montmorillonite K10 and ch aracterized in their ability to enhance the electrogenerated chemilumi nescence (ECL) in a solution containing luminol and hydrogen peroxide. Montmorillonite K10 proved to be an effective catalyst for such a pur pose: according to the anodic current and ECL intensity measured with the electrodes with and without clay particles. Under optimum conditio ns (pH 10 and 0.8 V vs. SCE), the ECL was enhanced by a factor of 10. Control experiments showed the enhanced ECL is likely due to a facilit ation in the oxidation of luminol and H2O2 by the iron species contain ed in the clay. Double-step potential techniques suggested that supero xide is very likely to be the key reactive oxygen species involved in the clay-enhanced ECL reaction. In addition, clay/luminol/GOx electrod es were constructed by using aminopropyltrimethoxysilane as an immobil izing agent for the detection of glucose. Although the electrode sensi tivity decreased by ca. 15% after 10 days, a linear calibration curve was attained, covering the concentrations of glucose from 10 mu M to 0 .5 mM with a detection limit at ca. 10 mu M at pH 10.