Verifying scalings for bending rigidity of bilayer membranes using mesoscale models

Abstract

The bending rigidity κ of bilayer membranes was studied with coarse grained soft repulsive potentials using dissipative particle dynamics (DPD) simulations. Using a modified Andersen barostat to maintain the bilayers in a tensionless state, the bending rigidity was obtained from a Fourier analysis of the height fluctuations. From simulations carried out over a wide range of membrane thickness, the continuum scaling relation κ ∝ d² was captured for both the L_α and L_β phases. For membranes with 4 to 6 tail beads, the bending rigidity in the L_β phase was found to be 10–15 times higher than that observed for the L_α phase. From the quadratic scalings obtained, a six fold increase in the area stretch modulus, k_A was observed across the transition. The magnitude of increase in both κ and k_A from the L_α to the L_β phase is consistent with current experimental observations in lipid bilayers and to our knowledge provides for the first time a direct evaluation of the mechanical properties in the L_β phase.