Influence of NaCl on the Structure and Dynamics of Phospholipid Layers

• Main Authors: Sebastian Jaksch, Olaf Holderer, Henrich Frielinghaus, Alexandros Koutsioubas, Piotr Zolnierczuk, Dominic William Hayward, Stephan Förster, Peter Müller-Buschbaum
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2021-05-01
• Series: Frontiers in Physics
• Subjects: phospholipids; salt; dynamics; structure; GISANS; neutron reflectometry
• Online Access: https://www.frontiersin.org/articles/10.3389/fphy.2021.628219/full

We present a structural and dynamical analysis of the influence of NaCl on multilayer stacks of phospholipids on a solid surface. To this end, multilayer stacks of phospholipids (L-α-phosphatidylcholine, abbreviated as SoyPC) are investigated with neutron reflectometry, grazing-incidence small-angle neutron scattering (GISANS) and grazing-incidence neutron-spin echo spectroscopy (GINSES). We show both that the NaCl influence on the structure is predominantly on water-head group interface and also, that the change in dynamics is restricted to an associated change in the inter-plane viscosity. Using this knowledge, it is possible to model the dynamical behavior of a phospholipid membrane in response to a salt concentration of the solvent using only a single parameter, namely the in-plane viscosity. The excellent agreement with our previously published model also strongly supports the existence of a thermally excited surface mode in phospholipid membranes for close-to-physiological conditions.