Functionalized Gold Nanoparticles – Octadecylamine Hybrid Langmuir-Blodgett Film for Enzyme Sensor

Mediator free enzyme sensor has been fabricated by covalently immobilizing cholesterol oxidase (ChOx) onto 11-mercaptoundecanoic acid functionalized gold nanoparticles (MUDA-AuNPs) – octadecylamine (ODA) hybrid Langmuir–Blodgett film. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies reveal that MUDA-AuNP/ODA LB film has good affinity for ChOx and provides favorable microenvironment for direct electron transfer between enzyme and electrode. Interference free estimation of cholesterol has been realized at 0.3 V with linear range from 25 to 500 mg/dL, detection limit of 23.38 mg/dL, sensitivity of 1.085 μA mM−1 and response time of 20 s at pH 7.0