Study of molecular orientational order in the Lagmuir monolayer

Vajda, J.; Weis, Martin; Barančok, D.; Cirák, J.; Tomčı́k, Peter

doi:10.1016/j.apsusc.2004.01.071

Cited by 10 publications

(8 citation statements)

References 9 publications

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“…The 〈cos ϑ〉 is the statistical mean value of cos ϑ, where ϑ is the angle between the vector of the dipole moment and the normal. Detailed analysis of the dipole moment projection of simple fatty acids is described elsewhere …”

Section: Resultsmentioning

confidence: 99%

Study of Gramicidin A−Phospholipid Interactions in Langmuir Monolayers: Analysis of Their Mechanical, Thermodynamical, and Electrical Properties

et al. 2006

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The mechanisms of interactions between gramicidin A (gA) and dimyristoylphosphatidylcholine (DMPC) in monolayers formed at the air-water interface were studied by analyzing their mechanical, thermodynamical, and electrical properties evaluated from measurements of pressure-area isotherms and of Maxwell displacement currents (MDC). A contactless method of recording MDC enabled us to monitor changes in the charge state of the monolayer-constituting molecules and to find the relation between a phase state of the monolayer and structural transitions of gA. The peptide-lipid interactions were quantified in terms of the excess of Gibbs free energy, excess entropy, as well as the molecular dipole moments at various gA/DMPC molar ratios, at various temperatures (in the gel phase and also in the liquid-crystalline phase of DMPC molecule), and at various surface pressures. It was found that the strongest interactions between gA and DMPC took place at the gA/DMPC molar ratio at around 0.25. At this monolayer composition, the phospholipids, via their carbonyl moieties, dominantly interact with the single helical gA, which mostly stands upright on the surface and is anchored by its C-terminus to the water surface, and prevent the formation of the intertwined helical gA dimers. The optimum ratio was confirmed also by anomalous electrical behavior of electrical dipole moments derived from MDC measurements.

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Section: Resultsmentioning

confidence: 99%

Study of Gramicidin A−Phospholipid Interactions in Langmuir Monolayers: Analysis of Their Mechanical, Thermodynamical, and Electrical Properties

et al. 2006

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“…The change of the orientation of the polarization vector can be expressed as Maxwell's displacement current flowing through the monolayer. As we have shown in our previous studies [8] the current flowing in the outer circuit can be expressed as the change of the induced charge in time…”

Section: Methodsmentioning

confidence: 99%

“…The potential energy was determined in accordance with our previous model of the monolayer [8]. The mutual pair interaction between molecules consists of two-body dipole-dipole interaction and Buckingham's modified potential [10] …”

Section: Methodsmentioning

confidence: 99%

“…The energy of such a cluster can be expressed as a sum of all pair interactions involved. The suitability of the Buckingham potential in seven-particle clusters of molecules was presented in [8]. For all our calculations a spatial averaged value of the cluster potential energy is used.…”

Section: Methodsmentioning

confidence: 99%

“…As described in our previous paper [8], it is reasonable to express the dependence of the generated current I as a function of the compression rate β(t) = dA/dt I(t) = I 0 β(t) β 0…”

Section: Lagrange's Motion Equationmentioning

confidence: 99%

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Study of relaxation processes in monomolecular films by the step compression experiment

et al. 2005

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Influence of vitamin C on alcohol binding to phospholipid monolayers

Weis

Kopáni

2008

Eur Biophys J

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The simple model of the biological membrane is provided by well-controlled lipid monolayers at the air-water interface. The Maxwell displacement current technique (MDC) provides novel approach to conformation study of the membrane models. The effect of alcohols is interaction with membrane molecules, mainly with the lipid head group and consequent changes in physical-chemical properties of the membrane. The aim of study is to detect changes in structural, electrical and mechanical properties of dipalmitoyl-phosphatidylcholine (DPPC) monolayer on the subphase of methanol-water and ethanol-water mixtures before and after addition of antioxidant agent, vitamin C. Monolayers properties are investigated by a surface pressure analysis (including mechanical properties evaluation) and the Maxwell displacement current measurement, the dipole moment projection calculation. Surface pressure-area isotherms show similar behaviour of the DPPC monolayer on alcohol-water mixtures independently on presence of vitamin C. Binding/adsorption process induces change of electron density distribution across monolayer and thus the molecular dipole moment. We observe small or negligible binding of methanol molecules on oxygen bonds of DPPC. Thus the antioxidant, vitamin C, has no significant effect. For ethanol-water mixtures is observed recovery of electrical properties in presence of antioxidant agent. We suppose that vitamin C regulates DPPC-ethanol molecules interaction.

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Study of molecular orientational order in the Lagmuir monolayer

Cited by 10 publications

References 9 publications

Study of Gramicidin A−Phospholipid Interactions in Langmuir Monolayers: Analysis of Their Mechanical, Thermodynamical, and Electrical Properties

Study of Gramicidin A−Phospholipid Interactions in Langmuir Monolayers: Analysis of Their Mechanical, Thermodynamical, and Electrical Properties

Study of relaxation processes in monomolecular films by the step compression experiment

Influence of vitamin C on alcohol binding to phospholipid monolayers

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