Fibre-optic biosensor for hypoxanthine and xanthine based on a chemiluminescence reaction

Fibre-optic biosensors were constructed for determination of hypoxanthine and xanthine. Xanthine oxidase and peroxidase were immobilized on different preactivated membranes which were subsequently mounted onto the tip of a fibre-optic bundle. The H2O2 generated by the reaction of hypoxanthine and xanthine oxidase was measured by chemiluminescence (CL) detection using luminol and peroxidase. A linear calibration curve of the sensors in the range of 1-316 microM hypoxanthine and 3.1-316 microM xanthine, respectively, with a detection limit of 0.55 microM hypoxanthine was obtained. Recovery of hypoxanthine ranged between 91 and 102%.