Contribution of dipolar bridging to phospholipid membrane interactions: A mean-field analysis

We develop a model of interacting zwitterionic membranes with rotating surface dipoles immersed in monovalent salt and implement it field theoretic formalism. In the mean-field regime salt, electrostatic forces between are characterized by non-uniform trend: at large membrane separations, interfacial on opposing sides behave as like-charge cations give rise to repulsive interactions; short anionic induced dipolar phosphate groups sets behavior intermembrane region. The attraction cationic nitrogens lipid headgroups leads adhesion surfaces via bridging. underlying competition components individual charges ion affinity respect separation distance; inter-membrane separations imply excess, while small nanometer-sized favor excess. This complex ionic selectivity may have relevant repercussions nanofiltration nanofluidic transport techniques.