Role of Phospholipid Asymmetry in Stability of Inverted Hexagonal Mesoscopic Phases

Abstract

We resolve new aspects of supported lipid bilayer (SLB) formation by temperature-controlled time-resolved fluorescence microscopy at low lipid concentrations (<40mM DMPC). The deposition rate increases after lipid has steadily accumulated on the surface to a density of ~80% of that required for a complete bilayer. Around this time, resolvable patches of bilayer appear. After reaching a density of ~150% bilayer, excess lipid is ejected back into solution while patches continue to nucleate and spread, rapidly merging into a continuous SLB. Measurements of lipid density at and around patch nucleation sites argue against the existence of a critical vesicle density necessary for rupture. We associate the increased rate of adhesion and subsequent loss of lipid with the emergence and disappearance of bilayer edges. We conclude that bilayer edges play a key role in the formation of SLBs, anchoring vesicles to the surface and inducing rupture.

Planar Confined Water Organisation in Lipid Bilayer Stacks of Phosphatidylcholine and Phosphatidylethanolamine

“…Amphiphilic lipid self-assemblies belong to the class of lyotropic liquid crystals, and as such, they display a variety of complex mesophases and nanostructures, depending on the environmental conditions, lipid type and molecular shape [1][2][3] . In this study, we focus on the biologically most significant fluid lamellar phase of phospholipids, which form the core matrix of plasma cell membranes [4][5][6] .…”