Interaction and Adhesion of Vesicles: Coupling between Attractive Interactions and Bilayer Membrane Flexibility

A simple model for vesicle interaction and adhesion, due to nonspecific colloidal forces, is presented. It is shown that possible coupling with the deformations of the bilayer lipid membrane may substantially enhance the effect of the attractive forces. Thus, the presence of a water core in the vesicle interior decreases the strength and the range of the van der Waals attraction, but the deformation of the lipid bilayers may compensate this effect to a certain extent. Therefore, the total attractive energy (in the absence of specific interactions or other sources of attraction like depletion forces, etc.) could be due to coupling between the van der Waals and bending elasticity forces. The presence of excess line energy may lead to the appearance of a barrier in the interactions. As a result, a complex energy versus distance profile could be observed.