Cholesterol biosensors prepared by electropolymerization of pyrrole

Abstract

AbstractBiosensors 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 μL were performed with a high reproducibility in the range of 0 to 250 μM 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 μM cholesterol and the sample throughput was 25 injections per hour. The response of the sensors toward ascorbic and uric acid was investigated.