Cholesterol biosensor based on N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane self-assembled monolayer

Cholesterol oxidase (ChOx) has been covalently immobilized onto two-dimensional self-assembled monolayer (SAM) of N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTS) deposited on the indium–tin oxide (ITO) coated glass plates using N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide (EDC/NHS) chemistry. These ChOx/AEAPTS/ITO bioelectrodes are characterized using contact angle (CA) measurements, UV–visible spectroscopy, atomic force microscopy (AFM), electrochemical impedance technique, and Fourier transform infrared (FT–IR) technique. The covalently immobilized ChOx-modified AEAPTS bioelectrodes are used for the estimation of cholesterol in solution using UV–visible technique. These cholesterol sensing bioelectrodes show linearity as 50 to 500 mg/dl for cholesterol solution, detection limit as 25 mg/dl, sensitivity as 4.499 × 10−5 Abs (mg/dl)−1, Km value as 58.137 mg/dl (1.5 mM), apparent enzyme activity as 1.81 × 10−3 U cm−2, shelf life of approximately 10 weeks, and electrode reusability as 10 times.