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.