Highly sensitive and selective electrochemiluminescence determination of cholesterol utilizing a functional electrode with a core-shell nanostructure.

A highly sensitive and selective method for the determination of cholesterol is required to evaluate trace amounts of cholesterol in test samples. In this work, selected gold nanoparticles (AuNPs) and 5-amino-2-mercapto-1,3,4-thiadiazole (AMT) were used and a thin film of three-dimensional gold–AMT core–shell nanoparticles (p-AMT–AuNPs) was prepared using an electrochemical method. Cholesterol oxidase was then bonded to the film surface to give a functional electrode. Based on catalysis by the electrode functionalized for cholesterol and a luminol–H2O2 electrochemiluminescence (ECL) system, a highly sensitive and selective ECL method was developed for the determination of cholesterol. Under optimized conditions, ECL intensity showed a good linear relationship with cholesterol over the concentration range 0.05–11.0 µg/ml, with a correlation coefficient of 0.999 and a limit of detection of 0.02 µg/ml. The proposed method was used to determine cholesterol in dairy products with a relative standard deviation of < 1.8% and recovery rates of 98.1–104%. Copyright © 2015 John Wiley & Sons, Ltd.