Lateral Phase Separation between Phospholipids and Adhesion Macromolecules on Two Adhering Membranes

Abstract

We study analytically the lateral phase separation produced between phospholipids and adhesion macromolecules on two adhering membranes from a static point of view. In this letter, the adhesion macromolecules are assumed as long-flexible polymer chains anchored by two extremities on the inner monolayer of the two adjacent plasma membranes by anchors-segments, which are big amphiphilic molecules. The aim is to quantify how these polymer chains can be driven from a dispersed phase to a dense one, under the variation of a suitable parameter such as temperature and membrane environment.... To investigate this demixtion transition, we elaborate a new field theory that allows us to derive the expression for the mixing free energy. From this, we extract the complete shape of the associated phase diagram in the composition-temperature plane. The essential conclusion is that the anchored polymer chains experience the significant attractive forces directly result from the shape deformations of two parallel membranes a mean-distance apart. Also, the solvent quality and the structure (length) of adhesion macromolecules have a strong influence on the compatibility domain of the mixture.