Thermodynamic and structural study of DMPC-alkanol systems dagger

Maria Klacsova*, Attila Bota, Peter Westh, Sergio de Souza Funari, Daniela Uhrikova, Pavol Balgavy

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The thermodynamic and structural behaviors of lamellar dimyristoylphosphatidylcholine-alkanol(abbreviation DMPC–CnOH, n = 8–18 is the even number of carbons in the alkyl chain) systemswere studied by using DSC and SAXD/WAXD methods at a 0–0.8 CnOH : DMPC molar ratio range. Up to n ≤ 10 a significant biphasic effect depending on the main transition temperature tm on the CnOH concentration was observed. Two breakpoints were revealed: turning point (TP), corresponding to theminimum, and threshold concentration (cT), corresponding to the end of the biphasic tendency. Thesebreakpoints were also observed in the alkanol concentration dependent change in the enthalpy of themain transition DHm. In the case of CnOHs with n > 10 we propose a marked shift of TP and cT to verylow concentrations; consequently, only increase of tm is observed. A partial phase diagram wasconstructed for a pseudo-binary DMPC–C12OH system. We suggest a fluid–fluid immiscibility of the DMPC–C12OH system above cT with a consequent formation of domains with different C12OH contents. At a constant CnOH concentration, the effects of CnOHs on DHm and bilayer repeat distancewere found to depend predominantly on the mismatch between CnOH and lipid chain lengths. Observed effects are suggested to be underlined by a counterbalancing effect of interchain van der Waals interactions and headgroup repulsion. 
Original languageEnglish
JournalPhysical Chemistry Chemical Physics
Volume23
Issue number14
Pages (from-to)8598-8606
Number of pages9
ISSN1463-9076
DOIs
Publication statusPublished - 2021

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