Polyelectrolyte-lipid complexes as membrane mimetic systems

The complexation of bilayer-forming lipids, synthetic molecules such as dihexadecylphosphate (DHP) or didodecyldimethylammoniumchloride (DDMA) or natural lipids such as diverse soybean-lecithins with polyelectrolytes results in stable, highly ordered mesomorphous materials. These complexes show a wide variety of structure modifications and very interesting mechanical, optical and dielectric properties. Complexes of polyelectrolytes and diverse lecithin derivatives need extra attention if these systems are to be considered as membrane mimetic systems, that is, we must learn about the properties of the natural cell membrane. From a materials point of view the main advantage of polyelectrolyte-surfactant complexes compared with other membrane mimetic systems (e.g. Langmuir-Blodgett films) is their superior mechanical and thermal stability. Usually it is possible to formulate the polyelectrolyte-surfactant complexes as free-standing films. In general, the mesophase within the film is thermally stable until one of the building elements, either the surfactant or the polyelectrolyte, decomposes.