Davood Ghanei Agh Kaariz - Department of Physics, Faculty of Sciences, Science and Research Branch, Islamic Azad University
Elham Darabi - Department of Physics, Faculty of Sciences, Science and Research Branch, Islamic Azad University
Seyed Mohammad Elahi - Department of Physics, Faculty of Sciences, Science and Research Branch, Islamic Azad University

AbstractIn this work, a new sensitive enzyme-based electrode for electrochemical cholesterol biosensor was fabricated based on a nanocomposite of Au nanoparticles, ZnO nanoparticles and multi-wall carbon nanotubes (Au/ZnO/MWCNTs). The nanocomposite was prepared by sol–gel method and deposited on FTO substrate by dip coating, followed by cholesterol oxidase (ChOx) enzyme immobilized (ChOx/Au/ZnO/MWCNTs). Structural properties and morphology of the nanocomposite have been studied using X-ray diffraction (XRD) and Field emission scanning electron microscopy (FESEM). The sample was subjected to Fourier transform infrared spectroscopy (FTIR) to determine functional groups. Electrochemical behavior of the electrode was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques as a function of cholesterol concentration. Electrochemical impedance spectroscopy (EIS) was also considered to study of surface modified electrodes. The ChOx/Au/ZnO/MWCNTs electrode has been found to have enhanced electron transfer and display excellent analytical linear performances. The fabricated electrode exhibited low detection limit (۰.۱ μM), high sensitivity (۲۵.۸۹ μA/μM) evaluated from DPV data in the detection range of ۰.۱–۱۰۰ µM and high selectivity in the determination of cholesterol over glucose and uric acid. The application of the ChOx/Au/ZnO/MWCNTs electrode in detection of cholesterol in human serum was also confirmed.

Electrochemical biosensor, Cholesterol, Cholesterol oxidase, Au nanoparticles, ZnO Nanoparticles, Multi, wall carbon nanotubes, Au/ZnO/MWCNTs nanocomposite