Miscibility Behavior of Binary Monolayers in Dependence on the Chain Length Differences and Film States of the Phosphatidylcholine/Phosphatidylethanolamine Mixtures

Dörfler, H.‐D.; Koth, Christian; Rettig, W.

doi:10.1006/jcis.1996.0328

Cited by 10 publications

(8 citation statements)

References 2 publications

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“…Because the highest deviation from the additivity rule is observed for the mixtures of X AmB between 0.5 and 0.7 (Figure ), one may assume that the highest stability of the complex is reached at X AmB = 0.66, corresponding to a system of 2:1 AmB/DPPA (i.e., the one in which a phospholipid molecule is sandwiched between two AmB molecules). The complexes of the same stoichiometry have been reported for similar systems. ,, Likewise, the slow, spontaneous mixing of separately spread monolayer components has been observed by several authors. − …”

Section: Discussionsupporting

confidence: 73%

Influence of a Spreading Method on the Properties of Amphotericin B−Dipalmitoyl Phosphatidic Acid Mixed Films at the Air/Water Interface

et al. 2000

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Using two different spreading techniquesmixed spreading and separate spreadingand film surface pressure measurements, the mixing behavior of the amphotericin B (AmB)/dipalmitoyl phosphatidic acid (DPPA) system was investigated.The Π−A isotherms were found to exhibit various “plateaus” suggesting the occurrence of different phase transitions of the monolayer. On the basis of the surface phase rule, the phase diagram of mixed films was elucidated. The AmB molecule takes two orientations in the monolayer state, i.e., horizontal and vertical, depending on the surface pressure. Horizontally oriented AmB and vertically oriented phospholipid form a mixed monolayer that deviates from ideal behavior. On the other hand, vertically oriented AmB molecules were found to be immiscible with DPPA in a monolayer, although both molecules are normal to the surface and parallel to each other. The deviations from ideality can be ascribed to the formation of an AmB/DPPA complex of 2:1 stoichiometry as a result of the existence of hydrogen bonds and ionic attractive forces between polar groups of the two components.

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Section: Discussionsupporting

confidence: 73%

Influence of a Spreading Method on the Properties of Amphotericin B−Dipalmitoyl Phosphatidic Acid Mixed Films at the Air/Water Interface

et al. 2000

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“…However, the finding that when ergosterol and AmB are spread separately on the substrate there is a gradual rise in the surface pressure of the low-pressure π− A inflection region as the two components diffuse into each other (Figure ) suggests that in all cases this region reflects the transition of AmB molecules from horizontal to vertical orientation, and that the rise in surface pressure is due to an increasing, presumably nonhydrophobic, attractive interaction between AmB and ergosterol molecules (minimal when the monolayer components are spread separately and left only for a short time (10 min) before film compression (Figure , curve 2), greater when the components are spread separately but left for a longer time (2 h) allowing mutual diffusion (Figure , curve 3), and greatest when the component mixture is prepared before the film is spread (Figure , curve 1)). The slow, spontaneous mixing of initially unmixed monolayer components has been observed by several authors. − Attractive interaction between AmB and ergosterol molecules would also account for the transition region of curve 1 in Figure occurring at smaller mean molecular areas than the low-pressure transition region of curve 2. It is hoped that further research using other techniques such as BAM or fluorescence microscopy may confirm these findings.…”

Section: Discussionmentioning

confidence: 59%

Interaction between Amphotericin B and Sterols in Monolayers. Mixed Films of Ergosterol−Amphotericin B

et al. 1999

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Analysis of the compression isotherms of ergosterol/amphotericin B (AmB) mixed monolayers spread on aqueous substrates shows the existence of interactions between the two components at AmB mole fractions between 0.1 and 0.7. At low surface pressure AmB molecules appear to lie horizontally in the A/W interface and ergosterol molecules to stand vertically, while at higher surface pressures the molecules of both components are vertically oriented at the interface.

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“…Thus, the results of Niccolai et al, related to mixed monolayers of 1-glycerol monooleoil (MON) and 1-glycerol monoestearoil (MOS), confirm the “empirical rule” that immiscibility of the components at the interface is due to their different orientations (MON, horizontal; MOS, vertical). Other authors , attribute the miscibility or immiscibility of the components to the physical state of their respective monolayers: when both are in the same surface state (for example in the expanded state), components are miscible at the interface, whereas if they are in different surface states (for example, liquid-expanded and liquid-condensed states), they are partially miscible or immiscible. In fact, this reference to the physical states of the monolayer is another way of considering the different orientations of the molecules at the interface, because the nature of the surface state depends on the arrangement of molecules on the water surface.…”

Section: Discussionmentioning

confidence: 99%

Interactions between Polymers and Lipid Monolayers at the Air/Water Interface: Surface Behavior of Poly(methyl methacrylate)−Cholesterol Mixed Films

Conde

Trillo

et al. 2010

J. Phys. Chem. B

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The behavior of mixed monolayers of cholesterol and poly(methyl methacrylate) (PMMA) with molecular weights of M(w) = 120,000 g/mol and M(w) = 15,000 g/mol was investigated at the air/water interface using Langmuir and Brewster angle microscopy techniques. From the data of surface pressure (pi)-area (A) isotherms, compressional modulus-surface pressure (C(s)(-1)-pi) curves, and film thickness, complemented with Brewster angle microscopy images, the interaction between the components was analyzed. Regardless of the surface pressure (pi = 10, 20, or 30 mN/m) at which the mean molecular/monomer areas (Am) were calculated, the Am-mole fraction plots (corresponding to X(PMMA) = 0.1, 0.3, 0.5, 0.7, and 0.9) show that all the experimental points obtained are placed on the theoretical straight line calculated according to the additivity rule. This fact, together with the existence of two collapses in the mixed monolayers and with the fact that the surface pressure of the liquid-expanded LE-L'E phase transition of PMMA does not change with the monolayer composition, demonstrates the immiscibility of the film components at the interface. The application of the Crisp phase rule to the phase diagram of PMMA-cholesterol mixed monolayers helps to explain the existence of a biphasic system, regardless of their composition and surface pressure. Besides, Brewster angle microscopy (BAM) images showed the existence of heterogeneous cholesterol domains with high reflectivity immersed in a homogeneous polymer separate phase with low reflectivity.

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Miscibility Behavior of Binary Monolayers in Dependence on the Chain Length Differences and Film States of the Phosphatidylcholine/Phosphatidylethanolamine Mixtures

Cited by 10 publications

References 2 publications

Influence of a Spreading Method on the Properties of Amphotericin B−Dipalmitoyl Phosphatidic Acid Mixed Films at the Air/Water Interface

Influence of a Spreading Method on the Properties of Amphotericin B−Dipalmitoyl Phosphatidic Acid Mixed Films at the Air/Water Interface

Interaction between Amphotericin B and Sterols in Monolayers. Mixed Films of Ergosterol−Amphotericin B

Interactions between Polymers and Lipid Monolayers at the Air/Water Interface: Surface Behavior of Poly(methyl methacrylate)−Cholesterol Mixed Films

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