Self-assembled, highly viscous, and optically transparent lipidic cubic phases are employed as matrices for enzyme-glucose dehydrogenase and vitamin K derivatives differing in hydrophobicity: phylloquinone (VitK(1)), menaquinone (VitK(2)), and menadione (VitK(3)). The lipidic cubic mesophase has been employed to hold these electroactive biological molecules in close vicinity of the electrode surface in order to study their behavior in the lipid environment by electrochemical methods. Liquid-crystalline properties of the analyzed samples of non-doped and doped phase were identified using X-ray and polarized microscopy. Incorporation of the enzyme together with the mediator in the lipidic matrix results in the formation of a catalytically active and stable film on the electrode surface and makes the modified electrode useful for the development of biosensors. Single-walled carbon nanotubes were employed to nanostructure the electrode surface in order to increase the working area of the electrode. (c) 2012 Elsevier Inc. All rights reserved.