Adsorbed and free lipid bilayers at the solid-liquid interface

Charitat, Thierry; Bellet-Amalric, E.; Fragneto, Giovanna; Graner, François

doi:10.1007/s100510050725

Cited by 179 publications

(248 citation statements)

References 28 publications

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“…2.A) [22]. All the experiments were performed in fluid phase at 58 • C. The first bilayer serves as a spacer to reduce the interaction between the floating second bilayer and the substrate and keeps it free to fluctuate [23,24].…”

Section: Fig 1: Schematic Representation Of the Effect Of Electric Fmentioning

confidence: 99%

Reduction in Tension and Stiffening of Lipid Membranes in an Electric Field Revealed by X-Ray Scattering

et al. 2016

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The effect of AC electric fields on the elasticity of supported lipid bilayers has been investigated at the microscopic level using grazing incidence synchrotron x-ray scattering. A strong decrease in the membrane tension up to 1mN/m and a dramatic increase of its effective rigidity up to 300k B T are observed for local electric potentials seen by the membrane 1V. The experimental results were analyzed using detailed electrokinetic modeling and non-linear Poisson-Boltzmann theory. Based on a modeling of the electromagnetic stress which provides an accurate description of bilayer separation vs pressure curves, we show that the decrease in tension results from the amplification of charge fluctuations on the membrane surface whereas the increase in bending rigidity results from direct interaction between charges in the electric double layer. These effects eventually lead to a destabilization of the bilayer and vesicle formation. Similar effects are expected at the tens of nanometer lengthscale in cell membranes with lower tension, and could explain a number of electrically driven processes.Electric fields can be used to destabilize lipid bilayers as in the electroformation process, the most popular method to form large unilamellar vesicles [1], or to manipulate the shape of vesicles [2][3][4]. Beyond biosensor applications and the investigation of fundamental mechanical, dynamical and binding properties of membranes using impedance spectroscopy or dielectric relaxation [5], the strong influence of electric fields on lipid membrane behavior is also used in numerous applications in cell biology, biotechnology and pharmacology [6, 7] such as cell hybridization [8], electroporation [9], electrofusion [10] and electropermeabilization [11]. All these effects imply a strong deformation of the membranes in the field, the understanding of which in terms of elastic properties is therefore of prime importance [12]. Theoretically, the effect of electric fields on membrane tension has been investigated in Ref. [13], which was extended to bending rigidity in Refs [14][15][16][17][18]. When placed in an electric field E, charges of opposite sign will accumulate at both sides of a membrane which can be seen as a capacitor with surface charge densities Σ ± (see Fig.1.A), allowing to calculate the normal component of the electromagnetic stress Σ 2 + − Σ 2 − /ǫ m [19]. For a flat membrane, a direct consequence is electrostriction: at equilibrium, the elastic response of the membrane (Young modulus ∼ 10 7 − 10 8 Pa [5,20]) bal- * Present address: Max Planck Institute for Dynamics and SelfOrganization (MPIDS), Göttingen 37077, Germany † thierry.charitat@ics-cnrs.unistra.fr ances the electrostatic pressure [21]. Beyond this simple effect, membrane fluctuations modify the boundary conditions for the electric field, leading to a subtle coupling between electrostatics and membrane elasticity. Due to membrane finite thickness d m , a bending deformation induces surface element variations of opposite sign on both interface leading to a net ...

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Section: Fig 1: Schematic Representation Of the Effect Of Electric Fmentioning

confidence: 99%

Reduction in Tension and Stiffening of Lipid Membranes in an Electric Field Revealed by X-Ray Scattering

et al. 2016

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“…Phospholipids thus selfassemble into bilayers, which can, in turn, form various structures: periodic lamellar phases, L ␣ , multiconnected lamellar phases ͑cubic or sponge phase, L 3 ͒, or vesicles, L 4 . Single phospholipid bilayers can also be deposited on a hydrophilic flat substrate using Langmuir-Blodgett transfer technique 4,5 or fusion of vesicles.…”

Section: A Amphiphilic Molecules and Self-assembled Systemsmentioning

confidence: 99%

Fluctuations and destabilization of single phospholipid bilayers

2008

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Supported phospholipid bilayers are interesting model systems for biologists and present fascinating physical properties. The authors present an extensive experimental study of the dynamic properties of supported bilayers. The structure and the equilibrium properties of single and double supported bilayers were investigated with neutron reflectivity. The submicronic fluctuation spectrum of a nearly free "floating" bilayer was determined using off-specular x-ray scattering: the surface tension of the bilayer, its bending modulus, and the intermembrane potential could be determined. Using fluorescence microscopy, the authors showed that this well-controlled single bilayer can form vesicles. Destabilization occurred either at the main gel-fluid transition of the lipids and could be interpreted in terms of a decrease in the bending rigidity or under an ac low-frequency electric field applied in the fluid phase. In the latter case, the authors also studied the effect of the electric field at the molecular length scale by neutron reflectivity. In both cases, destabilization leads to the formation of relatively monodisperse vesicles. This could give further understanding on the vesicle formation mechanism and on the parameters that determine the vesicle size.

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“…Some measurements were made on the reflectometer CRISP at the RutherfordAppleton Laboratory, ISIS, Didcot, 14 where the reflectivity profile is measured at a fixed angle using a white neutron beam, and others were made on the long wavelength diffractometer D16 where a monochromatic neutron beam is incident on the sample and the angle of incidence is varied, or the dedicated reflectometer, D17, at the Institut LaueLangevin, Grenoble. 15 The NR profile is determined by the profile of the scattering length density, , across the interface, which depends on the number density of each atomic species, n i , and its known scattering length, b i :…”

Section: Resultsmentioning

confidence: 99%

Neutron reflection study on soluble and insoluble poly[2-(2’-ethylhexyloxy)-5-methoxy-1,4-phenylenevinylene) films

Webster

Mitchell

Burn

et al. 2002

Journal of Applied Physics

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Articles you may be interested inReuse of AIP Publishing content is subject to the terms at: https://publishing.aip.org/authors/rights-and-permissions. Neutron reflection ͑NR͒ has been utilized to study the physical structure of the light-emitting polymer poly͓2-͑2'-ethylhexyloxy͒-5-methoxy-1,4-phenylenevinylene͒ ͑MEHPPV͒. Films of soluble MEHPPV ͑S-MEHPPV͒ and insoluble MEHPPV ͑I-MEHPPV͒ prepared via a chloro precursor polymer were investigated. For S-MEHPPV spin-coated films were found to contain two layers, one of low-density and thickness of Ϸ1360 Å with the second layer being thinner, Ϸ240 Å, but denser. The thicker layer only covered about 30% of the substrate surface. In contrast, I-MEHPPV formed uniform films across the substrate. We found that during the thermal conversion of the chloro precursor polymer the film thickness was maintained and it was only on cooling that the films contracted. Importantly, the thermal expansion and contraction of I-MEHPPV was reversible. NR showed that thermal annealing of I-MEHPPV had little affect on the films physical structure while for S-MEHPPV only the thinner layer was changed and became more dense. Photoluminescence spectra of S-MEHPPV before and after annealing showed that the densification observed in the neutron reflection measurements was mirrored in the emission properties of the polymer film.

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Adsorbed and free lipid bilayers at the solid-liquid interface

Cited by 179 publications

References 28 publications

Reduction in Tension and Stiffening of Lipid Membranes in an Electric Field Revealed by X-Ray Scattering

Reduction in Tension and Stiffening of Lipid Membranes in an Electric Field Revealed by X-Ray Scattering

Fluctuations and destabilization of single phospholipid bilayers

Neutron reflection study on soluble and insoluble poly[2-(2’-ethylhexyloxy)-5-methoxy-1,4-phenylenevinylene) films

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