Nonlinear dynamics and rupture of lipid bilayers

Abstract

The role of repulsive forces in the nonlinear dynamics of lipid bilayers is described, using a hydrodynamic approach. The lipid bilayer is considered as a fluid film with tangentially immobile surfaces and a general order parameter profile is assessed, depending on the degree of orientation of the hydrocarbon segments of the lipids. Rupture of the film occurs via the instability of the symmetric mode (squeezing) of vibration of the two surfaces. A nonlinear evolution equation for the squeezing mode is solved numerically as part of an initial value problem with periodic boundary conditions and a true rupture time is assessed. This makes it possible to identify two situations where the ordering of the lipid chains is lowered, in accordance with experimental results on fusion of lipid bilayers.