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Issue 44, 2019
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Mechanical properties of lipid bilayers: a note on the Poisson ratio

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Abstract

We investigate the Poisson ratio ν of fluid lipid bilayers, i.e., the question how area strains compare to the changes in membrane thickness (or, equivalently, volume) that accompany them. We first examine existing experimental results on the area- and volume compressibility of lipid membranes. Analyzing them within the framework of linear elasticity theory for homogeneous thin fluid sheets leads us to conclude that lipid membrane deformations are to a very good approximation volume-preserving, with a Poisson ratio that is likely about 3% smaller than the common soft matter limit Image ID:c9sm01290g-t1.gif. These results are fully consistent with atomistic simulations of a DOPC membrane at varying amount of applied lateral stress, for which we instead deduce ν by directly comparing area- and volume strains. To assess the problematic assumption of transverse homogeneity, we also define a depth-resolved Poisson ratio ν(z) and determine it through a refined analysis of the same set of simulations. We find that throughout the membrane's thickness, ν(z) is close to the value derived assuming homogeneity, with only minor variations of borderline statistical significance.

Graphical abstract: Mechanical properties of lipid bilayers: a note on the Poisson ratio

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Article information


Submitted
27 Jun 2019
Accepted
11 Oct 2019
First published
16 Oct 2019

Soft Matter, 2019,15, 9085-9092
Article type
Paper
Author version available

Mechanical properties of lipid bilayers: a note on the Poisson ratio

M. M. Terzi, M. Deserno and J. F. Nagle, Soft Matter, 2019, 15, 9085
DOI: 10.1039/C9SM01290G

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