Phase diagrams of pseudo-binary phospholipid systems I. Influence of the chain length differences on the miscibility properties of cephaline/cephaline/water systems

Dörfler, H.‐D.; Brezesinski, Gerald; Miethe, Peter

doi:10.1016/0009-3084(88)90094-1

Cited by 37 publications

(12 citation statements)

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“…The miscibility behavior observed in mixtures of fatty acid esters is analogous to that obtained for pseudo-binary water saturated phospholipid systems, as already described in [3][4][5][6]. On the assumption that the mixing components are identical in their head group structures, it can be concluded that demixing occurs only if the difference between the lengths of the hydrocarbon chains of the lipids or phospholipids exeeds 2 CH2-groups.…”

Section: Comparison Of the Phase Diagramssupporting

confidence: 74%

“…Experimental procedure, evaluation of measurements and derivation of phase diagrams were already described in detail [6]. Experimental procedure, evaluation of measurements and derivation of phase diagrams were already described in detail [6].…”

Section: Methodsmentioning

confidence: 99%

“…In our preceding publications [3][4][5][6] we presented a systematic survey of the miscibility behavior of phospholipids, especially of homologeous lecithins, cephalines, and lecithin/anesthetic systems [7]. Chemical compositions and structures of lipids or phospholipids, respectively, were related with intermolecular interaction and miscibility behavior.…”

Section: Introductionmentioning

confidence: 99%

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Phase and miscibility behavior of binary lipid systems

Dörfler

Pietschmann

1990

Colloid & Polymer Sci

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Differential scanning calorimetry was applied to study the phase diagrams of the following binary lipid systems: myristic acid (C13COOH) / pentadecanoic acid (C14COOH); palmitic acid methyl ester (C15COOMe) / heptadecanoic acid methyl ester (C16COOMe); palmitic acid methyl ester (C15COOMe) / stearic acid methyl ester (C17COOMe); palmitic acid methyl ester (CIsCOOMe) / arachidic acid methyl ester (C19COOMe). A distinct succession in the phase diagram types and phase regions was observed, according to the chemical structure of the mixing components. In the systems C13COOH/C14COOH; C15COOMe/C16COOMe and C16COOMe/ C17COOMe, both components are completely miscible in the low-and high-temperature phase. Contrasting with these three binary lipid systems, the system C15COOMe/ C14COOMe shows complete miscibility only in the high-temperature phase, but almost complete demixing in the solid state. In the phase diagram an incongruent melting "1:1 complex" is built up. This "complex" forms an eutectic mixture with the phase of C15COOMe and a peritectic system with C19COOMe.

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Section: Comparison Of the Phase Diagramssupporting

confidence: 74%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phase and miscibility behavior of binary lipid systems

Dörfler

Pietschmann

1990

Colloid & Polymer Sci

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“…[31,32] Therefore, it is reasonable to assume that melting of the chains is not the only contribution to the total enthalpy change. Possible contributions of the head groups are discussed below.…”

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confidence: 99%

Structure–Function Relationships of New Lipids Designed for DNA Transfection

et al. 2011

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Cationic liposome/DNA complexes can be used as nonviral vectors for direct delivery of DNA-based biopharmaceuticals to damaged cells and tissues. To obtain more effective and safer liposome-based gene transfection systems, two cationic lipids with identical head groups but different chain structures are investigated with respect to their in vitro gene-transfer activity, their cell-damaging characteristics, and their physicochemical properties. The gene-transfer activities of the two lipids are very different. Differential scanning calorimetry and synchrotron small- and wide-angle X-ray scattering give valuable structural insight. A subgel-like structure with high packing density and high phase-transition temperature from gel to liquid-crystalline state are found for lipid 7 (N'-2-[(2,6-diamino-1-oxohexyl)amino]ethyl-2,N-bis(hexadecyl)propanediamide) containing two saturated chains. Additionally, an ordered head-group lattice based on formation of a hydrogen-bond network is present. In contrast, lipid 8 (N'-2-[(2,6-diamino-1-oxohexyl)amino]ethyl-2-hexadecyl-N-[(9Z)-octadec-9-enyl]propanediamide) with one unsaturated and one saturated chain shows a lower phase-transition temperature and a reduced packing density. These properties enhance incorporation of the helper lipid cholesterol needed for gene transfection. Both lipids, either pure or in mixtures with cholesterol, form lamellar phases, which are preserved after addition of DNA. However, the system separates into phases containing DNA and phases without DNA. On increasing the temperature, DNA is released and only a lipid phase without intercalated DNA strands is observed. The conversion temperatures are very different in the two systems studied. The important parameter seems to be the charge density of the lipid membranes, which is a result of different solubility of cholesterol in the two lipid membranes. Therefore, different binding affinities of the DNA to the lipid mixtures are achieved.

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“…Techniques and evaluations of calorimetric measurements have been published previously [2,9]. The calorimetric measurements were performed with aqueous lecithin dispersions using a PerkinElmer DSC-2.…”

Section: Methods and Substancesmentioning

confidence: 99%

Phase diagrams and structures of lecithin/water systems with branched lecithin components

Dörfler

Pietschmann

1990

Colloid & Polymer Sci

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Abstract:The influence of chain branching on the phase transition parameters and structures of the homologous series of 1-(x-methylpalmitoyl)-2-hexadecyllecithins in the water-saturated two-phase region (50 wt.% water) were studied by differentialscanning-calorimetry as a function of the position x of methyl branching. With increasing x a linear decrease in the enthalpies and alternating temperatures of main transition were observed. The phase diagram of the ternary system 1-(3-methyl-palmitoyl)-2-hexadecyllecithin/1,2-dipalmitoyllecithin/water (50 wt.% water) showed that both components are completely miscible within the high-temperature phase (La-phase). However, in the low-temperature phase (gel phase), the components are partially miscible only. It follows that gel phases with interdigitated chains and those with tilted chains are not completely miscible. The phase diagram of the ternary system 1,2-di-(8-methylpalmitoyl)-lecithin/1,2-dipalmitoyllecithin/water (50 wt.% water) showed that both components are completely miscible within the high-temperature phase and lowtemperature phase. Within the concentration range between the mole fraction x = 0.91 and x = 0.97, a "drop-like" course in the phase diagram was obtained.

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Phase diagrams of pseudo-binary phospholipid systems I. Influence of the chain length differences on the miscibility properties of cephaline/cephaline/water systems

Cited by 37 publications

References 34 publications

Phase and miscibility behavior of binary lipid systems

Phase and miscibility behavior of binary lipid systems

Structure–Function Relationships of New Lipids Designed for DNA Transfection

Phase diagrams and structures of lecithin/water systems with branched lecithin components

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