Characterization of a New Biomimetic Multilayer System for Biomembrane Interaction Studies

During the past decade, a lot of focus was placed on investigation of the layer-by-layer (LbL) deposition of polyelectrolyte multilayers (PEM). It is proven to be a good technique for obtaining stable and functional supports for various bio-systems. In our work, we focus on investigation of interaction between chitosan/heparin PEM films and small unilamellar vesicles (SUV). The lipids chosen for this study are mixtures of zwitterionic POPC and cationic E-POPC resulting in a positive surface charge density of the vesicles. The self-assembly process of physisorption of subsequent polyelectrolyte layers was followed by the Surface Plasmon Resonance (SPR) technique, allowing investigation of the deposition efficiency and dynamics. Later the formation of the lipid bilayer on top of the PEM film with both chitosan and heparin as the top layer was investigated. Also the study of the polyelectrolyte film structure was done by atomic force microscopy (AFM). Both dry and fully hydrated films were observed. As the last step of the study, the structure of the lipid bilayer deposited on top of positive and negative PEM film was visualized with the AFM technique. The information obtained from the SPR and AFM experiments will be used for further investigation of the hydration state of the PEM films and the lipid bilayer by neutron reflectivity.