Fluorinated and hydrogenated cubic phases as matrices for immobilisation of cholesterol oxidase on electrodes

Liquid crystal cubic phases prepared from two different surfactants, monoolein and a fluorinated derivative of an ethoxylated alcohol, have been used as matrices to immobilise the cholesterol oxidase from Rhodococcus sp. The structures of the reverse bicontinuous cubic phases containing pure water or enzyme solution were determined using small angle X-ray scattering (SAXS). Gold and glassy carbon electrodes were modified with the liquid crystals containing the enzyme, and used as sensors for cholesterol detection. The electrochemical response of the glassy carbon/fluorinated system was shown to be a linear function of the cholesterol concentration. It is concluded that the cholesterol oxidase immobilised in an appropriate cubic phase can be successfully used as a sensing element for electrochemical detection of cholesterol in its micellar solutions.