Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK; ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 OQX, UK.
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
J Colloid Interface Sci. 2021 Aug 15;596:297-311. doi: 10.1016/j.jcis.2021.03.078. Epub 2021 Mar 18.
A biomembrane sample system where millimolar changes of cations induce reversible large scale (≥ 200 Å) changes in the membrane-to-surface distance is described. The system composes of a free-floating bilayer, formed adjacent to a self-assembled monolayer (SAM). To examine the membrane movements, differently charged floating bilayers in the presence and absence of Ca and Na, respectively, were examined using neutron reflectivity and quartz crystal microbalance measurements, alongside molecular dynamics simulations. In neutron reflectivity the variation of Ca and Na concentration enabled precision manipulation of the membrane-to-surface distance. Simulations suggest that Ca 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.
介绍了一种生物膜样品系统，其中阳离子的毫摩尔变化会引起膜到表面距离的可逆大幅变化（≥200 Å）。该系统由自由浮动双层组成，形成于自组装单层（SAM）的相邻位置。为了研究膜的运动，使用中子反射率和石英晶体微天平测量以及分子动力学模拟，分别检查了存在和不存在 Ca 和 Na 时带不同电荷的浮动双层。在中子反射率中，Ca 和 Na 浓度的变化可以精确控制膜到表面的距离。模拟表明，Ca 离子在 SAM 和双层之间形成桥接，而 Na 的结合更为扩散，特别是对双层的结合，无法完全克服阴离子浮动双层和阴离子 SAM 之间的排斥。与石英晶体微天平的重现性中子反射率结果表明，这种易于制备的样品系统具有成为标准分析工具的潜力，例如研究膜结合效应、内吞作用和细胞信号转导。
