Localized density pulses in lipid membranes on the piсosecond time scale

Abstract

Physical mechanisms for the modulation of lipid nanodomain dynamics and transport of small molecules across the lipid bilayer of biological membranes can have considerable functional significance. The longitudinal propagating compression–expansion mode in a single-component lipid bilayer is considered on a spatial scale comparable to the bilayer thickness. The expression used for free energy per lipid molecule includes a term with the gradient of the area per lipid molecule. The finite character of the stress relaxation time in the lipid bilayer, which causes significant attenuation of viscous damping at sufficiently high frequencies, is taken into account. A hydrodynamic ad hoc model that describes soliton-like excitations in the bilayer is proposed. The possibility of formation and propagation of nanoscale pulses of lipid density with velocities determined by surface compressibility of the bilayer (similarly to the propagation of sound) is demonstrated for the picosecond time scale.