Poly(Neutral Red)/Cholesterol Oxidase Modified Carbon Film Electrode for Cholesterol Biosensing

Abstract

New amperometric cholesterol oxidase (ChOx) based enzyme biosensors for cholesterol have been developed. The enzyme was immobilised with and without glutaraldehyde cross‐linking on top of carbon film electrodes modified with redox mediators. Mediators tested were: poly(neutral red) (PNR), Prussian blue and cobalt hexacyanoferrates. Amperometric detection of cholesterol showed that PNR/ChOx modified electrodes exhibited the best characteristics; under optimised conditions cholesterol was determined at −0.4 V vs. SCE with a detection limit of 1.9 µM. The biosensors showed good reproducibility and stability and only a small influence from potential interferents in food. Analyses of cholesterol in egg yolk were successfully performed.

New redox and conducting polymer modified electrodes for cholesterol biosensing

“…All these experimental observations led us to consider a mechanism in which hydrogen peroxide is reduced to water at the PMB polymer, enough oxygen remaining in the solution and in the enzymatic layer, aer nitrogen bubbling, in order to accept the electrons from the reduced FADH 2 . The same behaviour was observed in the case of a ChOx/poly(neutral red)(PNR) biosensor, 42 which reported the mechanism described above and presented in Scheme 1. A different response was observed in the case of a biosensor containing glucose oxidase instead of ChOx immobilized on top of the PEDOT/PMB/GCE, where direct electronic communication between PMB and the enzyme cofactor happens, so that the mediator is oxidized at the electrode surface aer receiving the electrons from the FADH 2 .…”

Oxidation Mechanism of Fluorescein at Glassy Carbon Electrode

“…Electrochemical techniques have been applied to help clarifying such drug mechanism of action and toxicity. Moreover, due to their high sensitivity, voltammetric methods have been successfully used for detection and determination of various pharmaceutical and hazardous compounds .…”

Poly(brilliant green) and poly(thionine) modified carbon nanotube coated carbon film electrodes for glucose and uric acid biosensors

“…Among them, redox dye polymers, especially phenazine derivatives, have had many applications in sensors and biosensors e.g. [6][7][8][9]. CP/CNT nanocomposite modified electrodes have received significant interest because the incorporation of conducting polymers into CNT can lead to new composite materials possessing the properties of each component, with a synergistic effect that would be useful in specific applications [10].…”