Formation of supported bacterial lipid membrane mimics.

In recent years, a large effort has been spent on advancing the understanding of how surface-supported membranes are formed through vesicle fusion. The aim is to find simple model systems for investigating biophysical and biochemical interactions between constituents of cell membranes and, for example, drugs and toxins altering membrane function. Designing and controlling the self-assembly of model membranes onto sensor substrates thus constitutes an important field of research, enabling applications in, e.g., drug screening, dynamic biointerfaces, artificial noses, and research on membrane-active antibiotics. The authors have developed and investigated the formation of strongly negatively charged supported lipid membranes which systematically mimic bacterial membrane composition on three important biosensor materials: SiO(2), TiO(2), and indium tin oxide. By tuning the electrostatic interaction through balancing the lipid vesicle charge with the ionic strength of Ca(2+) as a fusion promoter, the authors have optimized the self-assembly and obtained new insights into the details of lipid vesicle-surface interaction. The results will be useful for future development and application of specialized lipid membrane surface coatings prepared from complex lipid compositions. The adsorption processes were characterized by a quartz crystal microbalance with dissipation monitoring, optical waveguide lightmode spectroscopy, and fluorescence recovery after photobleaching, which allowed the determination of formation also of nonplanar supported lipid membranes.