Polysaccharides have beenassociated with various biological functions through their binding tomembranes, but their specific role is still under debate. The aim of this workwas to study the interaction of cationic and anionic lipids with Dextran Sulphate,an anionic polymer, and the influence of this interaction on the membrane mechanicalstability. The interaction was studied by determinations of the zeta potentialusing LUVs and of the interface reflectivity with Brewster Angle Microscopyusing Langmuir monolayers. The membrane stability was studied in LUVs byfollowing the response upon osmotic shocks or the addition of detergent. Theevolution of the vesicles was followed with neferometry, Dynamic LightScattering and by the fluorescence increment due to the release ofcarboxyfluorescein. In addition, GUVs were observed in the absence and in thepresence of the polymer and the shape fluctuations were analyzed.
The results indicate that thepolymer interacts with the cationic membrane, and also with the anionicmembrane but in this case, in a Ca2+-dependent manner. The influenceof the polymer on the stability upon detergent and osmotic shocks, as well ason the shape fluctuations depends on the membrane composition.
