Dynamics of an asymmetric bilayer lipid membrane in a viscous solvent

• Published in: Europhysics letters Vol. 111; no. 1; pp. 18004 - p1-18004-p6
• Main Authors: Bingham, R. J., Smye, S. W., Olmsted, P. D.
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences, IOP Publishing and Società Italiana di Fisica 01-07-2015; IOP Publishing
• Subjects: 87.15.A; 87.16.D; 87.16.dj; Asymmetry; Coupled modes; Density; Dynamics; Joining; Lipids; Mathematical models; Membranes; Monolayers; Solvents
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/0295-5075/111/18004

Bilayer lipid membranes (BLMs) are an essential component of many biological systems, forming a functional barrier between the cell and the surrounding environment. When the membrane relaxes from a structural perturbation, the dynamics of the relaxation depends on the bilayer structure. We present a model of a BLM in a viscous solvent, including an explicit description of a "thick" membrane, where the fluctuations in the thickness of a monolayer leaflet are coupled to changes in the lipid density within that monolayer. We find dispersion relations describing three intuitive forms of bilayer motion, including a mode describing motion of the intermonolayer surface not noted previously in the literature. Two intrinsic length scales emerge that help characterise the dynamics; the well-known Saffman-Delbrück length and another, , resulting from the intermonolayer friction. The framework also allows for asymmetry in the BLM parameters between the monolayer leaflets, which is found to couple dynamic modes of bilayer motion.