CHOLESTEROL BIOSENSORS PREPARED BY ELECTROPOLYMERIZATION OF PYRROLE

Biosensors for cholesterol were prepared by electropolymerization of pyrrole in solutions of 0.1 M phosphate buffer containing 10 mm NaClO4 and 15 to 55 IU/mL of cholesterol oxidase at a potential of 800 mV versus a calomel reference electrode (3 M KCl). The sensors were tested for their response toward cholesterol in batch, flow-through, and flow-injection systems by detection of the hydrogen peroxide formed in the enzymatic reaction. Flow-injection analysis (FIA) measurements with an injection loop of 50 muL were performed with a high reproducibility in the range of 0 to 250 muM cholesterol with solutions of constant detergent concentration (1% Triton X-100 in 0.1 M phosphate buffer of pH 7.0) and at a flow rate of 0.2 mL/min. At this flow rate, the detection limit was approximately 5 muM cholesterol and the sample throughput was 25 injections per hour. The response of the sensors toward ascorbic and uric acid was investigated.