New redox and conducting polymer modified electrodes for cholesterol biosensing

New enzyme biosensors for cholesterol detection based on a recently developed transduction platform constituted of a GCE modified with polymer redox mediator poly(methylene blue) (PMB) and conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) were for the first time prepared and evaluated. The enzyme cholesterol oxidase (ChOx) was immobilized by simple adsorption, the ChOx/PEDOT/PMB/GCE biosensor being applied for amperometric determination of cholesterol by monitoring the peroxide reduction produced by the enzymatic reaction at -0.4 V vs. SCE. Amperometric studies at fixed potential reveal that almost interference-free cholesterol determination can be achieved at the newly developed biosensor in a range between 10 and 220 mu M with a sensitivity of 79.0 mu A cm(-2) mM(-1) and a detection limit of 1.6 mu M. The recovery and storage stability of the biosensor were evaluated and the biosensor was applied to cholesterol detection in whole cow milk and chicken egg yolk.