title: Relaxation and curvature-induced molecular flows within multicomponent membranes.
abstract: The quantitative understanding of membranes is still rooted in work performed in the 1970s by Helfrich and others, concerning amphiphilic bilayers. However, most biological membranes contain a wide variety of nonamphiphilic molecules too. Drawing analogy with the physics of nematic-non-nematic mixtures, we present a dynamical (out-of-equilibrium) description of such multicomponent membranes. The approach combines nematohydrodynamics in the linear regime and a proper use of (differential-) geometry. The main result is to demonstrate that one can obtain equations describing a cross-diffusion effect (similar to the Soret and Dufour effects) between curvature and the (in-membrane) flow of amphiphilic molecules relative to nonamphiphilic ones. Surprisingly, the shape of a membrane relaxes according to a simple heat equation in the mean curvature, a process that is accompanied by a simultaneous boost to the diffusion of amphiphiles away from regions of high curvature. The model also predicts the inverse process, by which the forced bending of a membrane induces a flow of amphiphilic molecules towards areas of high curvature. In principle, numerical values for the relevant diffusion coefficients should be verifiable by experiment.
authors.affiliation: Theoretical Physics, The University of Warwick, Coventry CV4 7AL, United Kingdom.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Morris
mesh_terms: D002462:Cell Membrane / Q000737:chemistry*; D004058:Diffusion; D004548:Elasticity; D057446:Hydrodynamics; D016014:Linear Models; D008560:Membrane Fluidity; D008954:Models, Biological; D013816:Thermodynamics