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    Large scale model lipid membrane movement induced by a cation switch

    Year: 2021

    Journal: J. Colloid Interface Sci., Volume 596, AUG 15, page 297–311

    Authors: John, Laura H.; Preston, Gail M.; Sansom, Mark S. P.; Clifton, Luke A.

    Organizations: UKRI-BBSRC Interdisciplinary Bioscience Doctoral Training Partnership [BB/M011224/1]; ISIS facility development studentship programme

    Keywords: Biological membranes; Biosensors; Distance tuning; Biomimetic; Model membranes; Cation switch; Calcium; Electrostatics; Neutron reflectometry; Molecular dynamics; Self-assembled monolayer; Cation binding

    A biomembrane sample system where millimolar changes of cations induce reversible large scale (> 200 angstrom) changes in the membrane-to-surface distance is described. The system composes of a freefloating bilayer, formed adjacent to a self-assembled monolayer (SAM). To examine the membrane movements, differently charged floating bilayers in the presence and absence of Ca2+ and Na+, respectively, were examined using neutron reflectivity and quartz crystal microbalance measurements, alongside molecular dynamics simulations. In neutron reflectivity the variation of Ca2+ and Na+ concentration enabled precision manipulation of the membrane-to-surface distance. Simulations suggest that Ca2+ ions bridge between SAM and bilayer whereas the more diffuse binding of Na+, especially to bilayers, is unable to fully overcome the repulsion between anionic floating bilayer and anionic SAM. Reproduced neutron reflectivity results with quartz crystal microbalance demonstrate the potential of this easily producible sample system to become a standard analysis tool for e.g. investigating membrane binding effects, endocytosis and cell signaling. (C) 2021 The Authors. Published by Elsevier Inc.
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