The formation and growth of compositional domains within multicomponent lipid bilayer membranes has been experimentally reported in several lipid systems.  Recent findings demonstrate further that stacked bilayer membrane systems can exhibit long range interlayer alignment of compositional domains, with an emergent columnar order extending over hundreds of membranes.  The average domain size in such systems was found to increase in time as a power law with exponent ~0.455, in apparent discord with the diffusion-limited Ostwald ripening scaling exponent of ~1/3 reported for single membrane systems.  However, the detailed physical mechanism responsible for the intermembrane coupling is not well-understood, nor is the nature of the subsequent alignment-induced coarsening regime with enhanced scaling exponent.<br/> <br/>We combine numerical simulations of an advective diffuse-interface description of multimembrane lamellae with theoretical sharp interface analysis and dynamic scaling arguments to provide a quantitative analysis of the effect of interlayer coupling on domain growth and long range intermembrane alignment.  Our description incorporates the effects of thermodynamic intermembrane coupling, membrane/solvent hydrodynamics, intermembrane friction, and lipid diffusion.  Three alignment-driven dynamic scaling regimes are identified for diffusion-dominated, advection/interlayer friction-dominated, and advection/membrane viscosity-dominated systems, respectively. The noted experimental systems are shown to be within the advection/interlayer friction-dominated regime, for which we predict a scaling exponent of 1/2, in good agreement with reported values. We also propose a quantitative measure of domain alignment based on an intermembrane correlation function, and demonstrate that its behavior is closely related with that of the domain scaling.

Interlayer coupling and compositional domain growth in stacked lipid bilayer membrane systems

251st National Meeting (2016)

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