TY  - JOUR
AU  - Fink, Lea
AU  - Steiner, Ariel
AU  - Szekely, Or
AU  - Szekely, Pablo
AU  - Raviv, Uri
TI  - Structure and Interactions between Charged Lipid Membranes in the Presence of Multivalent Ions
JO  - Langmuir
VL  - 35
IS  - 30
SN  - 0743-7463
CY  - Washington, DC
PB  - ACS Publ.
M1  - PUBDB-2024-01026
SP  - 9694 - 9703
PY  - 2019
AB  - When aqueous salt solutions contain multivalent ions (like Ca2+ or Mg2+), strong correlation effects may lead to ion-bridging, net attraction, and tight-coupling between like-charged interfaces. To examine the effects of surface charge density, temperature, salt type, and salt concentration on the structures of tightly coupled charged interfaces, we have used mixed lipid membranes, containing either saturated or unsaturated tails in the presence of multivalent ions. We discovered that tightly coupled membrane lamellar phases, dominated by attractive interactions, coexisted with weakly coupled lamellar phases, dominated by repulsive interactions. To control the membrane charge density, we mixed lipids with negatively charged headgroups, DLPS and DOPS, with their zwitterionic analogue having the same tails, DLPC and DOPC, respectively. Using solution X-ray scattering we measured the lamellar repeat distance, D, at different ion concentrations, temperatures, and membrane charge densities. The multivalent ions tightly coupled the mixed lipid bilayers whose charged lipid molar fraction was between 0.1 and 1. The repeat distance of the tightly coupled phase was about 4 nm for the DLPS/DLPC mixtures and about 5 nm for the DOPS/DOPC mixtures. In this phase, the repeat distance slightly increased with increasing temperature and decreased with increasing charge density. When the molar fraction of charged lipid was 0.1 or 0.25, a less tightly coupled phase coexisted with the tightly coupled phase. The weakly coupled lamellar phase had significantly larger D values, although they were consistently shorter than the D values in monovalent salt solutions with similar screening lengths.
LB  - PUB:(DE-HGF)16
C6  - pmid:31283884
UR  - <Go to ISI:>//WOS:000479019700006
DO  - DOI:10.1021/acs.langmuir.9b00778
UR  - https://bib-pubdb1.desy.de/record/604167
ER  -