Molecular Dynamics Investigations of Lipid Langmuir Monolayers Using a Coarse-Grain Model

Nielsen, Steven O.; López, Carlos F.; Moore, Preston B.; Shelley, John C.; Klein, Michael L.

doi:10.1021/jp035262c

Cited by 55 publications

(62 citation statements)

References 26 publications

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“…[13][14][15][16][17] In line with previous simulations of a DMPA monolayer, [18,19] we obtained the free-energy profile (DG) for MB transfer from bulk aqueous solution to the interior of the monolayer, as well as the MB orientation as a function of the distance from the lipid monolayer.…”

Section: Introductionmentioning

confidence: 80%

Methylene Blue Adsorption on a DMPA Lipid Langmuir Monolayer

et al. 2010

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Adsorption of methylene blue (MB) onto a dimyristoylphosphatidic acid (DMPA) Langmuir air/water monolayer is studied by molecular dynamics (MD) simulations, UV reflection spectroscopy and surface potential measurements. The free-energy profile associated with MB transfer from water to the lipid monolayer shows two minima of -66 and -60 kJ mol(-1) for its solid and gas phase, respectively, corresponding to a spontaneous thermodynamic process. From the position of the free-energy minima, it is possible to predict the precise location of MB in the interior of the DMPA monolayer. Thus, MB is accommodated in the phosphoryl or carbonyl region of the DMPA Langmuir air/water interface, depending on the isomorphic state (solid or gas phase, respectively). Reorientation of MB, measured from the bulk solution to the interior of the lipid monolayer, passes from a random orientation in bulk solution to an orientation parallel to the surface of the lipid monolayer when MB is absorbed.

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Section: Introductionmentioning

confidence: 80%

Methylene Blue Adsorption on a DMPA Lipid Langmuir Monolayer

et al. 2010

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“…As for semi-atomistic models of bilayers, a number of interesting approaches have been suggested. 24,25,26,27,28,29,30,31,32,33 The guiding principle is that small groups of atoms are represented as single interaction sites, thus reducing the computational complexity of the model. In the model by Marrink et al 24 there are Lennard-Jones, harmonic, and electrostatic interactions between the coarse-grained particles, and the interaction parameters have been tuned to match experimental quantities such as heats of vaporization or densities.…”

Section: Introductionmentioning

confidence: 99%

“…The approach by Lipowsky et al is somewhat more phenomenological but similar in nature. 25,26,27 Shelley et al, in turn, have employed a large variety of different interactions between the coarse-grained particles, 31,32,33 and the interaction parameters have been adjusted to match results from both experiments and atomic simulations. Groot and Rabone have employed the dissipative particle dynamics (DPD) technique and chosen soft potentials between the coarse-grained particles.…”

Section: Introductionmentioning

confidence: 99%

Coarse-grained model for phospholipid/cholesterol bilayer

Murtola

Falck

Patra³

et al. 2004

The Journal of Chemical Physics

127

152

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We construct a coarse-grained (CG) model for dipalmitoylphosphatidylcholine (DPPC) / cholesterol bilayers and apply it to large-scale simulation studies of lipid membranes. Our CG model is a two-dimensional representation of the membrane, where the individual lipid and sterol molecules are described by point-like particles. The effective intermolecular interactions used in the model are systematically derived from detailed atomic-scale molecular dynamics simulations using the Inverse Monte Carlo technique, which guarantees that the radial distribution properties of the CG model are consistent with those given by the corresponding atomistic system. We find that the coarse-grained model for the DPPC / cholesterol bilayer is substantially more efficient than atomistic models, providing a speed-up of approximately eight orders of magnitude. The results are in favor of formation of cholesterol-rich and cholesterol-poor domains at intermediate cholesterol concentrations, in agreement with the experimental phase diagram of the system. We also explore the limits of the novel coarse-grained model, and discuss the general validity and applicability of the present approach.

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“…Previous simulations of monolayer collapse (22,23) considered relatively small systems (with box lateral size Ϸ10 nm), which limited both the modes of monolayer collapse and the variety of possible lipid aggregates that could be observed. Although these simulations allowed displacements of individual molecules from the interface, a collective molecular response to collapse was energetically unfavorable.…”

mentioning

confidence: 99%

The molecular mechanism of lipid monolayer collapse

Baoukina

Monticelli

Risselada

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

255

253

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Lipid monolayers at an air-water interface can be compressed laterally and reach high surface density. Beyond a certain threshold, they become unstable and collapse. Lipid monolayer collapse plays an important role in the regulation of surface tension at the air-liquid interface in the lungs. Although the structures of lipid aggregates formed upon collapse can be characterized experimentally, the mechanism leading to these structures is not fully understood. We investigate the molecular mechanism of monolayer collapse using molecular dynamics simulations. Upon lateral compression, the collapse begins with buckling of the monolayer, followed by folding of the buckle into a bilayer in the water phase. Folding leads to an increase in the monolayer surface tension, which reaches the equilibrium spreading value. Immediately after their formation, the bilayer folds have a flat semielliptical shape, in agreement with theoretical predictions. The folds undergo further transformation and form either flat circular bilayers or vesicles. The transformation pathway depends on macroscopic parameters of the system: the bending modulus, the line tension at the monolayer-bilayer connection, and the line tension at the bilayer perimeter. These parameters are determined by the system composition and temperature. Coexistence of the monolayer with lipid aggregates is favorable at lower tensions of the monolayerbilayer connection. Transformation into a vesicle reduces the energy of the fold perimeter and is facilitated for softer bilayers, e.g., those with a higher content of unsaturated lipids, or at higher temperatures.lung surfactant ͉ bilayer reservoir ͉ course grain ͉ vesicle budding ͉ molecular dynamics L ipid molecules are insoluble in both polar and apolar media because of their amphipathic nature. At polar-apolar interfaces, they form monomolecular films that reduce the surface tension. Lipid monolayers form the main structural component (Ϸ97% by weight) of lung surfactant at the gas-exchange interface in the lung alveoli (1) and constitute the outer layer of tear film in the eyes (2). The properties of lipid monolayers vary with their surface density (3). For example, the higher the density, the lower is the resulting surface tension at the interface. At a certain very high surface density, however, a further reduction of the surface tension is not possible: the monolayers become unstable at the interface and collapse (4) (see scheme in Fig. 1). Besides being of fundamental interest for surface science, lipid monolayer collapse is crucial for maintaining low surface tension at the gas-exchange interface in the lungs during breathing (5).Collapse is characterized by loss of material from the interface and can proceed through different pathways. The modes of collapse and the surface tension at which collapse occurs depend on the molecular composition of the monolayer and on temperature (6-13), which determine the morphology and material properties of the monolayer. Although lipid monolayers in the liquid state do not usually ...

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Molecular Dynamics Investigations of Lipid Langmuir Monolayers Using a Coarse-Grain Model

Cited by 55 publications

References 26 publications

Methylene Blue Adsorption on a DMPA Lipid Langmuir Monolayer

Methylene Blue Adsorption on a DMPA Lipid Langmuir Monolayer

Coarse-grained model for phospholipid/cholesterol bilayer

The molecular mechanism of lipid monolayer collapse

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