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Issue 37, 2015
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Viscoelastic deformation of lipid bilayer vesicles

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Lipid bilayers form the boundaries of the cell and its organelles. Many physiological processes, such as cell movement and division, involve bending and folding of the bilayer at high curvatures. Currently, bending of the bilayer is treated as an elastic deformation, such that its stress–strain response is independent of the rate at which bending strain is applied. We present here the first direct measurement of viscoelastic response in a lipid bilayer vesicle. We used a dual-beam optical trap (DBOT) to stretch 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) giant unilamellar vesicles (GUVs). Upon application of a step optical force, the vesicle membrane deforms in two regimes: a fast, instantaneous area increase, followed by a much slower stretching to an eventual plateau deformation. From measurements of dozens of GUVs, the average time constant of the slower stretching response was 0.225 ± 0.033 s (standard deviation, SD). Increasing the fluid viscosity did not affect the observed time constant. We performed a set of experiments to rule out heating by laser absorption as a cause of the transient behavior. Thus, we demonstrate here that the bending deformation of lipid bilayer membranes should be treated as viscoelastic.

Graphical abstract: Viscoelastic deformation of lipid bilayer vesicles

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Article information

25 Jun 2015
06 Aug 2015
First published
06 Aug 2015

Soft Matter, 2015,11, 7385-7391
Article type
Author version available

Viscoelastic deformation of lipid bilayer vesicles

S. Wu, S. Sankhagowit, R. Biswas, S. Wu, M. L. Povinelli and N. Malmstadt, Soft Matter, 2015, 11, 7385
DOI: 10.1039/C5SM01565K

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