posted on 2021-11-03, 17:34authored byTereza Schönfeldová, Paulina Piller, Filip Kovacik, Georg Pabst, Halil I. Okur, Sylvie Roke
Morphological and
gel-to-liquid phase transitions of lipid membranes
are generally considered to primarily depend on the structural motifs
in the hydrophobic core of the bilayer. Structural changes in the
aqueous headgroup phase are typically not considered, primarily because
they are difficult to quantify. Here, we investigate structural changes
of the hydration shells around large unilamellar vesicles (LUVs) in
aqueous solution, using differential scanning calorimetry (DSC), and
temperature-dependent ζ-potential and high-throughput angle-resolved
second harmonic scattering measurements (AR-SHS). Varying the lipid
composition from 1,2-dimyristoyl-sn-glycero-3-phosphocholine(DMPC)
to 1,2-dimyristoyl-sn-glycero-3-phosphate (DMPA),
to 1,2-dimyristoyl-sn-glycero-3-phospho-l-serine (DMPS), we observe surprisingly distinct behavior for the
different systems that depend on the chemical composition of the hydrated
headgroups. These differences involve changes in hydration following
temperature-induced counterion redistribution, or changes in hydration
following headgroup reorientation and Stern layer compression.