Spontaneous curvature of bilayer membranes from molecular simulations: Asymmetric lipid densities and asymmetric adsorption

Różycki, Bartosz; Lipowsky, Reinhard

doi:10.1063/1.4906149

Cited by 111 publications

(137 citation statements)

References 54 publications

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“…However, this mechanism alone cannot significantly affect the λ-value. On the other hand, recent work has shown that an asymmetry in the nature of fluids surrounding the bilayer can also influence the curvature-density coupling, even in the case of a single-component membrane [40]. Moreover, spontaneous curvature can be generally taken into account using a term similar to the coupling term in Eq.…”

Section: Vesicle Free Energymentioning

confidence: 99%

Relaxation dynamics of a compressible bilayer vesicle containing highly viscous fluid

2016

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We study the relaxation dynamics of a compressible bilayer vesicle with an asymmetry in the viscosity of the inner and outer fluid medium. First we explore the stability of the vesicle free energy which includes a coupling between the membrane curvature and the local density difference between the two monolayers. Two types of instabilities are identified: a small wavelength instability and a larger wavelength instability. Considering the bulk fluid viscosity and the inter-monolayer friction as the dissipation sources, we next employ Onsager's variational principle to derive the coupled equations both for the membrane and the bulk fluid. The three relaxation modes are coupled to each other due to the bilayer and the spherical structure of the vesicle. Most importantly, a higher fluid viscosity inside the vesicle shifts the cross-over mode between the bending and the slipping to a larger value. As the vesicle parameters approach toward the unstable regions, the relaxation dynamics is dramatically slowed down, and the corresponding mode structure changes significantly. In some limiting cases, our general result reduces to the previously obtained relaxation rates.

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Section: Vesicle Free Energymentioning

confidence: 99%

Relaxation dynamics of a compressible bilayer vesicle containing highly viscous fluid

2016

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“…In our particle-based model, each of the chains consists of six beads of type C and the head group is built up from three beads of type H. The non-adhesive particles are represented by single beads of type P. As in our previous simulation study, 3 we take all beads, including the particle beads, to have the same diameter d, which is convenient from a computational point of view. Furthermore, the separation of the two head group layers is about 5d.…”

Section: A Dissipative Particle Dynamicsmentioning

confidence: 99%

“…For lipid bilayers, this separation has a typical value of 4 nm which implies that the bead diameter d ≃ 4 nm/5 = 0.8 nm. 3 The interactions between the DPD beads are parametrized in the usual form, 3,21,25 the corresponding DPD parameters a i j are given in Table II. These parameters describe the strength of the repulsive forces between the soft-core particles.…”

Section: A Dissipative Particle Dynamicsmentioning

confidence: 99%

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Membrane curvature generated by asymmetric depletion layers of ions, small molecules, and nanoparticles

Różycki

Lipowsky

2016

The Journal of Chemical Physics

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Erratum: "Membrane curvature generated by asymmetric depletion layers of ions, small molecules, and nanoparticles" [J. Chem. Phys. 145, 074117 (2016) Biomimetic and biological membranes consist of molecular bilayers with two leaflets that are typically exposed to different aqueous solutions. We consider solutions of "particles" that experience effectively repulsive interactions with these membranes and form depletion layers in front of the membrane leaflets. The particles considered here are water-soluble, have a size between a few angstrom and a few nanometers as well as a rigid, more or less globular shape, and do neither adsorb onto the membranes nor permeate these membranes. Examples are provided by ions, small sugar molecules, globular proteins, or inorganic nanoparticles with a hydrophilic surface. We first study depletion layers in a hard-core system based on ideal particle solutions as well as hard-wall interactions between these particles and the membrane. For this system, we obtain exact expressions for the coverages and tensions of the two leaflets as well as for the spontaneous curvature of the bilayer membrane. All of these quantities depend linearly on the particle concentrations. The exact results for the hard-core system also show that the spontaneous curvature can be directly deduced from the planar membrane geometry. Our results for the hard-core system apply both to ions and solutes that are small compared to the membrane thickness and to nanoparticles with a size that is comparable to the membrane thickness, provided the particle solutions are sufficiently dilute. We then corroborate the different relationships found for the hard-core system by extensive simulations of a soft-core particle system using dissipative particle dynamics. The simulations confirm the linear relationships obtained for the hard-core system. Both our analytical and our simulation results show that the spontaneous curvature induced by a single particle species can be quite large.

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“…Two opposing forces, interfacial tension and steric repulsion, produce the inhomogeneous stress inside the bilayers [19]. This inhomogeneity is a key property of the bilayers because it determines the area per lipid molecule [19], spontaneous curvature [20][21][22][23][24], Gaussian curvature modulus [21][22][23][24][25][26][27][28], and function of the mechanosensitive channel [29,30]. Since the stress profile cannot be obtained experimentally [31,32], estimation using molecular simulations is important.…”

Section: Introductionmentioning

confidence: 99%

Nonuniqueness of local stress of three-body potentials in molecular simulations

Nakagawa

Noguchi

2016

Phys. Rev. E

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Microscopic stress fields are widely used in molecular simulations to understand mechanical behavior. Recently, decomposition methods of multibody forces to central force pairs between the interacting particles have been proposed. Here, we introduce a force center of a three-body potential and propose different force decompositions that also satisfy the conservation of translational and angular momentum. We compare the force decompositions by stress-distribution magnitude and discuss their difference in the stress profile of a bilayer membrane using coarse-grained and atomistic molecular dynamics simulations.

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Spontaneous curvature of bilayer membranes from molecular simulations: Asymmetric lipid densities and asymmetric adsorption

Cited by 111 publications

References 54 publications

Relaxation dynamics of a compressible bilayer vesicle containing highly viscous fluid

Relaxation dynamics of a compressible bilayer vesicle containing highly viscous fluid

Membrane curvature generated by asymmetric depletion layers of ions, small molecules, and nanoparticles

Nonuniqueness of local stress of three-body potentials in molecular simulations

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