Statistical mechanics of a colloidal suspension in contact with a fluctuating membrane

Bickel, Thomas; Benhamou, M.; Kaidi, H.

doi:10.1103/physreve.70.051404

Cited by 12 publications

(10 citation statements)

References 31 publications

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“…Adsorption of colloidal particles on a flexible interface is an essential step in many biological processes, and the underlying physics of this mecha- * Electronic adress: th.bickel@cpmoh.u-bordeaux1.fr nism has been extensively studied for simple model systems [8,9,10,11]. Thermal undulations of the surface are nevertheless disregarded in most theoretical works, even though they are expected to locally alter the particle distribution [12,13]. Technically, the difficulty lies in the interplay between bulk and surface degrees of freedom.…”

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confidence: 99%

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Surface-mediated attraction between colloids

Kaidi

Bickel²,

Benhamou

2005

Europhys. Lett.

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We investigate the equilibrium properties of a colloidal solution in contact with a soft interface. As a result of symmetry breaking, surface effects are generally prevailing in confined colloidal systems. In this Letter, particular emphasis is given to surface fluctuations and their consequences on the local (re)organization of the suspension. It is shown that particles experience a significant effective interaction in the vicinity of the interface. This potential of mean force is always attractive, with range controlled by the surface correlation length. We suggest that, under some circumstances, surface-induced attraction may have a strong influence on the local particle distribution. Colloidal suspensions are solutions of fairly large objects, with typical size ranging from 1 nm to 1 µm. The primary question of their stability and phase behaviour is the foundation of many technological applications [1]. Formally, the statistical description of a colloidal dispersion involves colloid-colloid, colloid-solvent and solventsolvent interactions. However, such detailed and complex information is usually not required to understand essential features, and it has been found more appropriate to develop effective descriptions where the colloids interact through a potential of mean force [2]. The individual forces acting between particles then depend explicitly on the temperature and on the chemical potential of the solvent. Examples of such effective potentials include dispersion forces, DLVO theory for charged systems, or depletion interactions in polydispersed solutions.On the other hand, it has been recognized long ago that surface effects are prevailing in confined colloidal systems [3,4]. The mutual influence of bulk and surface properties on each other is a challenging problem, that conversely may lead to unusual behaviours. For instance, when a bidispersed hard-sphere suspension is brought in contact with a flat substrate, excluded-volume effects are known to push the larger beads toward the wall of the sample [5]. Recent experiments done with curved or corrugated surfaces have shown that geometric features of the surface can also create and modulate entropic force fields [6]. These depletion forces can be used to grow oriented colloidal crystal, with numerous potential applications such as the fabrication of photonic bandgap crystals [7].In this Letter, we present some new findings regarding the static organization of nanoparticles near a fluctuating surface. Adsorption of colloidal particles on a flexible interface is an essential step in many biological processes, and the underlying physics of this mecha-

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confidence: 99%

“…Note that in the case of colloid-surface repulsion (ω < 0), colloids are depleted from the interface and the corresponding adsorbance is negative (see also ref. [13]). Finally, let us comment on the limit of an infinitely rigid interface, corresponding to κ ≫ k B T .…”

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confidence: 99%

Surface-mediated attraction between colloids

Kaidi

Bickel²,

Benhamou

2005

Europhys. Lett.

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“…The opposite case has been investigated theoretically in Ref. 31 and it was proposed that strong shape fluctuations lead to a constant density profile of the particles adjacent to a fluctuating membrane. The latter proposal has not been addressed here and remains to be corroborated by molecular simulations.…”

Section: Discussionmentioning

confidence: 99%

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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“…We give an explication to this distance-scale by saying that it presents the length of the correlation in the plane (size of the hole and the valley of membrane's undulations). The latter depends on the bilayer membrane characteristics [40][41][42] through the modulus of curvature, k, and the interfacial tension, g. According to M. Benhamou et al corrections, 38 the characteristics of the membrane k, g, the potential amplitude A(n) and the renormalized range z(n) depend on the number density of NIs, n. Thus, to propose an explicit variation-law to present these quantities as a function of the density, the authors assert it is a typical value, n 0 , where the bilayer membrane ceases to be uid, then becomes rigid. Therefore, at n ¼ n 0 , the ripple of the membrane disappears, that is, z(n) ¼ 0.…”

Section: Simulation Methods 21 Interaction Potentialmentioning

confidence: 99%