Carbon Nanotube Based Amperometric Biosensor for the Quantitative Detection of Cholesterol

A high sensitive and stable amperometric biosensor was developed using cholesterol oxidase, chitosan and multiwall carbon nano tubes (MWCNT’s) in order to determine total cholesterol in serum samples. Cholesterol oxidase was covalently immobilized on MWCNT’s; this enzyme was coated over glassy carbon electrode (GCE) and then a layer of chitosan deposited to prevent enzyme leaching. The ChOx/MWCNT/Chitosan was characterized using fourier transformed-infrared (FT-IR), scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and amperometric analyses. These studies indicate immobilization of cholesterol oxidase on MWCNTs, an efficient detection method for cholesterol. The optimum performance of the modified electrode was at pH 7.0 at 40°C. The optimized biosensor possessed a minimum detection limit of 0.13μM (S/N=3) with a fast response time (~5s) and a wide linear range 0.16 to 9.69 mM (25 to 500 mg/dL) (N = 10, R2 > 0.99) and 92% stability up to 7 months. The proposed amperometric biosensor is highly sensitive and exhibits no interference with serum metabolites viz. glucose, uric acid, ascorbic acid and billirubin at their physiological concentrations ranges. Thus, the electrochemical biosensor fabricated in the present investigation is promising for cholesterol detection in blood.