Revealing the kinetics of ionophore facilitating ion transport across lipid bilayers by surface enhanced infrared absorption spectroscopy

Ionophore can prominently improve the ion permeability of cell membrane and disrupt cellular ion homeostasis. Most studies regarding ionophore facilitating ion transmembrane transport focus on artificial liquid-liquid interfaces, which have large difference from the actual environment of cell membrane. Here, we construct a supported lipid bilayer on a gold nanoparticles film modified ZnSe prism as an appropriate model of cell membrane to investigate the dynamic of the ion transport facilitated by ionophore using surface enhanced infrared absorption spectroscopy (SEIRAS). We find that the ion transmembrane transport consists of two steps: The ion transmembrane transport starts with the association/disassociation between ion and ionophore at the edge of lipid bilayer; The second step is the transfer of ion-ionophore complex across lipid bilayer. Our results show that the complex transfer across the lipid bilayer is the rate determining step. (C) 2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.