Molecular simulations of mesoscopic bilayer phases

Dissipative particle dynamics simulations are used to study the self-assembly of lipids into bilayers. With a simple mesoscopic lipid-water model, we observe the formation of the liquid crystalline phase $L_{\alpha }$ and gel phases in which the tails are interdigitated $L_{\beta I}$ or noninterdigitated $L_{\beta }.$ For double-tail lipids experiments show all three phases, while for single-tail lipids only $L_{\beta }$ and $L_{\alpha }$ are observed. We show that at sufficiently high head-head repulsion the $L_{\beta I}$ is stable for single-tail lipids. This suggests that it might be possible to induce an $L_{\beta }\to L_{\beta I}$ transition by adding chaotropic salts.