Effect of Temperature on the Interactions between Dipolar Membranes

Abstract

It is well-known that phospholipids in aqueous environment self-assemble into lamellar structures with a repeat distance governed by the interactions between them. Yet, the understanding of these interactions is incomplete. In this paper, we study the effect of temperature on the interlamellar interactions between dipolar membranes. Using solution small-angle X-ray scattering (SAXS), we measured the repeat distance between 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) bilayers at different temperatures and osmotic stresses. We found that when no pressure is applied the lamellar repeat distance, D, decreases and then increases with increasing temperature. As the osmotic stress increases, D decreases with temperature and then increases to a limited extent, until at sufficiently high pressure D decreases with temperature in all the examined range. We then reconstructed experimentally the equation of state and fit it with a modified interaction model that takes into account the temperature dependence of the fluctuation term. Finally, we showed how the thickness of DLPC membranes decreases with temperature.

Pathological transitions in myelin membranes driven by environmental and multiple sclerosis conditions

“…4 , red square symbols). Previous studies had shown such behavior, explained by a decrease in the membrane thickness ( ) with increasing temperature ( 59 ). The different trends can be explained by the formation of a mixed phase at modified lipid composition, and a single lamellar phase at the native lipid composition.…”

“…For example, at elevated temperature, the lamellar to hexagonal phase transition has been demonstrated for single and binary lipids mixtures ( 24 , 56 – 58 ). The origin of this thermotropic phase transition is the added mobility of the hydrocarbon chains at elevated temperatures, leading to larger spontaneous curvature ( 23 , 59 ). The contribution of hydrocarbon chains’ entropy to the free energy increases with temperature.…”

“…The contribution of hydrocarbon chains’ entropy to the free energy increases with temperature. As more hydrocarbon chains’ conformation is available, the membrane thickness decreases to reduce the interfacial area between the aqueous solution and the lipid hydrocarbon chains ( 59 ). Moreover, temperature has an additional effect on the intermolecular forces between the water molecules.…”

Structure and Intermolecular Interactions between L-Type Straight Flagellar Filaments

“…To apply osmotic stress to the flagellar filaments and induce bundle formation, we used polyethylene glycol (PEG) of molecular mass 20 kDa (purchased from Sigma-Aldrich (St. Louis, MO) and used as received). Osmotic stress samples were prepared by mixing PEG and flagellar filament solutions, as described elsewhere (16)(17)(18)(19). The osmotic pressure, P, of each polymer solution was measured using a vapor pressure osmometer (Vapro 5520, Wescor, Pittsburgh, PA) and verified against the well-established (20) expression log p ¼ a þ b  ðwt%Þ c , where a ¼ 1:57, b ¼ 2:75, and c ¼ 0:21.…”

Comportamiento termo fluidodinámico del acero en un molde de colada continua: una revisión

“…En [43] se mostró un modelo lineal y otro cuadrático para determinar la conductividad térmica del acero en estado líquido, pastoso y sólido en el molde. En la zona de conducción en el acero sólido, la conductividad térmica del acero sólido se ha asumido constante [48], [49] o lineal con la temperatura [50], sin embargo, no debe descuidarse su influencia, porque habrá una mayor transferencia de calor donde la capa de acero es más delgada (en el menisco) y disminuirá con la longitud del molde. Además, por tratarse de una aleación, se formará una zona pastosa cuya conductividad térmica dependerá de las fases [11], [12], [16], y esto afecta la transferencia de calor.…”