Thermodynamic and structural study of DMPC-alkanol systems

The thermodynamic and structural behaviors of lamellar dimyristoylphosphatidylcholine-alkanol (abbreviation DMPC-C n OH, n = 8-18 is the even number of carbons in the alkyl chain) systems were studied by using DSC and SAXD/WAXD methods at a 0-0.8 C n OH : DMPC molar ratio range. Up to n ≤ 10 a signi...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2021-04, Vol.23 (14), p.8598-866
Main Authors: Klacsová, Mária, Bóta, Attila, Westh, Peter, de Souza Funari, Sérgio, Uhríková, Daniela, Balgavý, Pavol
Format: Article
Language:English
Subjects:
Chains
Enthalpy
Lipids
Low concentrations
Miscibility
Phase diagrams
Transition temperature
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Summary:The thermodynamic and structural behaviors of lamellar dimyristoylphosphatidylcholine-alkanol (abbreviation DMPC-C n OH, n = 8-18 is the even number of carbons in the alkyl chain) systems were studied by using DSC and SAXD/WAXD methods at a 0-0.8 C n OH : DMPC molar ratio range. Up to n ≤ 10 a significant biphasic effect depending on the main transition temperature t m on the C n OH concentration was observed. Two breakpoints were revealed: turning point (TP), corresponding to the minimum, and threshold concentration ( c T ), corresponding to the end of the biphasic tendency. These breakpoints were also observed in the alkanol concentration dependent change in the enthalpy of the main transition Δ H m . In the case of C n OHs with n > 10 we propose a marked shift of TP and c T to very low concentrations; consequently, only increase of t m is observed. A partial phase diagram was constructed for a pseudo-binary DMPC-C12OH system. We suggest a fluid-fluid immiscibility of the DMPC-C12OH system above c T with a consequent formation of domains with different C12OH contents. At a constant C n OH concentration, the effects of C n OHs on Δ H m and bilayer repeat distance were found to depend predominantly on the mismatch between C n OH and lipid chain lengths. Observed effects are suggested to be underlined by a counterbalancing effect of interchain van der Waals interactions and headgroup repulsion. A fluid-fluid immiscibility of the DMPC-C12OH system above threshold concentration with a consequent formation of domains with different C12OH contents is suggested.
ISSN:1463-9076
1463-9084
DOI:10.1039/d0cp04991c