title: Effect of temperature on the structure of charged membranes.
abstract: Interactions between charged and neutral self-assembled phospholipid membranes are well understood and take into account temperature dependence. Yet, the manner in which the structure of the membrane is affected by temperature was hardly studied. Here we study the effect of temperature on the thickness, area per lipid, and volume per lipid of charged membranes. Two types of membranes were studied: membranes composed of charged lipids and dipolar (neutral) membranes that adsorbed divalent cations and became charged. Small-angle X-ray scattering data demonstrate that the thickness of charged membranes decreases with temperature. Wide-angle X-ray scattering data show that the area per headgroup increases with temperature. Intrinsically charged membranes linearly thin with temperature, whereas neutral membranes that adsorb divalent ions and become charged show an exponential decrease of their thickness. The data indicate that, on average, the tails shorten as the temperature rises. We attribute this behavior to higher lipid tail entropy and to the weaker electrostatic screening of the charged headgroups, by their counterions, at elevated temperatures. The latter effect leads to stronger electrostatic repulsion between the charged headgroups that increases the area per headgroup and decreases the bilayer thickness.
authors: The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel.
authors: Pablo
authors: P
authors: Szekely
authors: Tom
authors: T
authors: Dvir
authors: Roi
authors: R
authors: Asor
authors: Roi
authors: R
authors: Resh
authors: Ariel
authors: A
authors: Steiner
authors: Or
authors: O
authors: Szekely
authors: Avi
authors: A
authors: Ginsburg
authors: Jonathan
authors: J
authors: Mosenkis
authors: Vicky
authors: V
authors: Guralnick
authors: Yoav
authors: Y
authors: Dan
authors: Tamar
authors: T
authors: Wolf
authors: Carmen
authors: C
authors: Tamburu
authors: Uri
authors: U
authors: Raviv
mesh_terms: D019277:Entropy; D008051:Lipid Bilayers / Q000737:chemistry*; D053838:Scattering, Small Angle; D055672:Static Electricity; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D008051:Lipid Bilayers