In situ preparation of a cholesterol biosensor: entrapment of cholesterol oxidase in an overoxidized polypyrrole film electrodeposited in a flow system: Determination of total cholesterol in serum Original Research Article

A straightforward method for constructing cholesterol biosensors by entrapment of cholesterol oxidase within a polypyrrole (PPy) film electropolymerized in a flow system is proposed. This method enables adjustment of the biosensor characteristics and features low reagent consumption. Prior to use, the PPy film is overoxidized to provide it with anion-exclusion properties in order to minimize the interference of electroactive species such as ascorbic acid and uric acid. A comprehensive preliminary study of the influence of 2-propanol and Triton X-100 added to the cholesterol solution on the flow-injection determination of this substrate, and the effects of different experimental variables on the biosensor response and its selectivity against interfering electroactive species was carried out. The proposed cholesterol oxidase based biosensor, named Pt/PPy–ChOx, was applied to the determination of cholesterol in reference serum samples, and the results were consistent with certified values.