SPE biosensor for cholesterol in serum samples based on electrochemiluminescent luminol copolymer

A poly(luminol–3,3′,5,5′-tetramethylbenzidine) copolymer manufactured by electropolymerization on screen-printed gold electrodes greatly improves the electrochemiluminescence of hydrogen peroxide. Cholesterol oxidase was immobilized on the surface of a poly(luminol–3,3′,5,5′-tetramethylbenzidine) screen-printed cell modified with chitosan to prepare an ECL biosensor for cholesterol. Working under the optimized conditions, the linear dynamic range of cholesterol was 2.4 × 10−5–1.0 × 10−3 M with a limit of detection of 7.3 × 10−6 M and a precision of 10.3% (5.0 × 10−4 M, n = 5) expressed as relative standard deviation. This biosensor was applied to the determination of total cholesterol in serum samples obtaining satisfactory results with respect to the reference procedure. This cholesterol biosensor offers an alternative analytical method with low cost and high speed.