Glycerol-induced membrane stiffening: the role of viscous fluid adlayers |
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Authors: | Pocivavsek Luka Gavrilov Kseniya Cao Kathleen D Chi Eva Y Li Dongxu Lin Binhua Meron Mati Majewski Jaroslaw Lee Ka Yee C |
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Institution: | †Department of Chemistry, University of Chicago, Chicago, Illinois;‡Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois;§Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico;¶Los Alamos National Laboratory, Los Alamos, New Mexico |
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Abstract: | Lipid interfaces, ranging from cell membranes to thin surfactant layers that stabilize lung alveoli, are integral to living systems. Such interfaces are often subjected to mechanical forces, and because of their membrane-like geometry, they can easily deform by bending into localized folds. In this work, we explore the role of small molecules (i.e., glycerol) on the mechanical stability of model lung surfactant monolayers. We demonstrate that the presence of glycerol increases local monolayer bending stiffness by orders of magnitude. Our x-ray and neutron reflectivity measurements indicate that water is preferentially depleted, or glycerol is preferentially enriched, at the lipid headgroup/solvent interface, and that this glycerol-enriched layer extends beneath the monolayer with an adsorption free energy of −2.5 to −4.6 kJ/mol. The dramatic change in membrane bending stiffness in the presence of the sugar adlayer is understood in terms of two models: 1), lipid antiplasticization by glycerol; and 2), a continuum mechanical model of the viscous adlayer. |
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