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

Liquid crystal cubic phases prepared from two different surfactants, monool ein 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 o r 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 e lectrochemical response of the glassy carbon/fluorinated system was shown t o be a linear function of the cholesterol concentration. It is concluded th at the cholesterol oxidase immobilised in an appropriate cubic phase can be successfully used as a sensing element for electrochemical detection of ch olesterol in its micellar solutions.