Biocompatible self-assembled monolayer platform based on (3-glycidoxypropyl)trimethoxysilane for total cholesterol estimation

Abstract

An electrochemical cholesterol biosensor has been fabricated via covalent immobilization of cholesterol oxidase and cholesterol esterase (ChOx and ChEt) onto a biocompatible self assembled monolayer (SAM) of (3-glycidoxypropyl)trimethoxysilane (GPTMS) fabricated onto an indium tin oxide (ITO) electrode. The ChOx/GPTMS/ITO bioelectrode has been characterized using Fourier transform infrared spectroscopy (FTIR), contact angle measurements (CA), atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) techniques. The results of the electrochemical response studies indicate that the ChOx-ChEt/GPTMS/ITO biosensing electrode can be used to estimate the total cholesterol from 1.5 to 6.1 mM, has sensitivity of 0.351 μA (mg/dl)⁻¹, and can be used more than 10 times with a shelf life of up to 10 weeks. The value of the Michaelis–Menten constant (K_m) observed as 0.43 mM reveals a strong binding to the biocompatible GPTMS organic platform and shows low interference effect. Further, this biosensor can be used to estimate the total cholesterol concentration in serum samples.