Sensitive estimation of total cholesterol in blood using Au nanowires based micro-fluidic platform

Determination of cholesterol level in blood is important in clinical applications. In this work, modified Au nanowires—electrochemical biosensor based on MEMS micro-fluidic platform is proposed for estimating total cholesterol in blood. This sensor consists of “aligned” Au nanowires as working electrode, platinum counter electrode deposited on the silicon platform and Ag/AgCl (3 M KCl) reference electrode. The “aligned” Au nanowires are immobilized with cholesterol oxidase and cholesterol esterase using specific covalent chemistry. Further, Au nanowires promotes better electron transfer between the enzymes and electrodes, because of their large surface to volume ratio, small diffusion time, large electrical conductivity and their aligned nature. The modified Au nanowires showed a stable calibration line and a quasi-linear relationship between cholesterol level and current response in the range of 1–6 mM (in steps of 1 mM over the baseline blood serum). The sensitivity of the modified electrode was found to be about 69 nA/mM with good storage and interference stability.