Immobilization of cholesterol esterase and cholesterol oxidase onto sol-gel films for application to cholesterol biosensor

Cholesterol oxidase (ChOx) and cholesterol esterase (ChEt) have been covalently immobilized onto tetraethylorthosilicate (TEOS) sol-gel films. The tetraethylorthosilicate sol-gel/ChEt/ChOx enzyme films thus prepared have been characterized using scanning electron microscopic (SEM), UV-vis spectroscopic, Fourier-transform-infrared (FTIR) spectroscopic and amperometric techniques, respectively. The results of photometric measurements carried out on tetraethylorthosilicate sol-gel/ChEL/ChOx reveal thermal stability up to 55 degrees C, response time as 180 s, linearity up to 780 mg dL(-1) (12 nM), shelf life of 1 month, detection limit of 12 mg dL(-1) and sensitivity as 5.4 x 10(-5) Abs. mg(-1) dL(-1). (c) 2006 Elsevier B.V. All rights reserved.