Electrochemical Cholesterol Sensor Based on Tin Oxide-Chitosan Nanobiocomposite Film

A chitosan (CS)-tin oxide (SnO2) nanobiocomposite film has been deposited onto an indium-tin-oxide glass plate to immobilize cholesterol oxidase (ChOx) for cholesterol detection. The value of the Michaelis-Menten constant (K-m) obtained as 3.8 mM for ChOx/CS-SnO2/ITO is lower (8 mM) than that of a ChOx/CS/ITO bioelectrode revealing enhancement in affinity adn/or activity ChOx towards cholesterol and also revealing strong binding of ChOx onto CS-SnO2/ITO electrode. This ChOx/CS-SnO2/ITO Cholesterol sensor retains 95%, of enzyme activity after 4-6 weeks at 4 C with response time of 5 s, sensitivity of 34.7 mu A/mg dL (1) cm(2) and detection limit of 5 mg/dL.