Compositional-mechanical instability of interacting mixed lipid membranes

We consider lateral phase separations in mixed vesicles that are comprised of neutral and charged lipids and which interact with each other at close distances. Their demixing transition is driven by the electrostatic interaction between the bilayers, and is due to enhanced screening of the in-plane repulsions by counterions shared between the two surfaces. Buckling of the membranes further facilitates the phase separation and lowers the interbilayer energy. We propose this instability as a precursor for vesicle fusion.