Amperometric determination of cholesterol in serum using a biosensor of cholesterol oxidase contained within a polypyrrole-hydrogel membrane

A rapid, two-step method for constructing cholesterol biosensors. by entrap ment of cholesterol oxidase (ChOx) within a composite poly(2-hydroxyethyl m ethacrylate)(p(HEMA))/polypyrrole (p(pyrrole)) membrane has been developed. Platinum electrode-supported polymer films were prepared by UV polymerizat ion of the hydrogel component containing dissolved enzyme followed immediat ely by electrochemical polymerization of entrapped pyrrole monomer (Py) wit hin the performed hydrogel network. The optimized cholesterol biosensor exh ibited a linear response range from 5 x 10(-4) to 1.5 x 10(-2) M and detect ion limit of 120 muM toward cholesterol. The response time of the biosensor was 30 s. The analytical recovery of cholesterol in serum samples ranged f rom 97 to 103% with mean coefficients of variation of 3% (within-day analys es) and 3.9% (day-to-day analyses). Up to 60 samples/h can be manually anal yzed. The cholesterol biosensor retained 80% of initial activity after 12 m onths when stored desiccated in the absence of buffer. When applied to the analysis of cholesterol in serum samples of clinical patients, >0.998 corre lation was obtained between the biosensor results and those obtained by a s tandard hospital method using an Abbott V.P, Chemistry Analyzer. (C) 2001 E lsevier Science B.V. All rights reserved.