Adhesion-induced phase behavior of multicomponent membranes - art. no. 011903

Biomimetic membranes that contain several molecular components are studied theoretically. In contact with another surface, such as a solid substrate o r another membrane, some of these intramembrane components are attracted by the second surface and, thus, act as local stickers. The cooperative behav ior of these systems is characterized by the interplay of (i) attractive bi nding energies, (ii) entropic contributions arising from the shape fluctuat ions of the membranes, and (iii) the entropy of mixing of the stickers. A s ystematic study of this interplay, which starts from the corresponding part ition functions, reveals that there are several distinct mechanisms for adh esion-induced phase separation within the membranes. The first of these mec hanisms is effective for flexible stickers with attractive cis interactions (within the same membrane) and arises from the renormalization of these in teractions by the confined membrane fluctuations. A second, purely entropic mechanism is found for rigid stickers without attractive cis interactions and arises from a fluctuation-induced line tension. Finally, a third mechan ism is present if the membrane contains both stickers and repellers, i.e., nonadhesive molecules that protrude from the membrane surface. This third m echanism is based on an effective potential barrier and becomes less effect ive if the shape fluctuations of the membrane become more pronounced.