Investigation of temperature induced mechanical changes in supported bilayers by variants of tapping mode atomic force microscopy: Investigation of mechanical changes in bilayers
- Award ID(s):
- 1054211
- NSF-PAR ID:
- 10018308
- Date Published:
- Journal Name:
- Scanning
- Volume:
- 37
- Issue:
- 1
- ISSN:
- 0161-0457
- Page Range / eLocation ID:
- 23 to 35
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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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 . 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.more » « less