Electrostatic and electrokinetic contributions to the elastic moduli of a driven membrane

Lacoste, David; Menon, Gautam I.; Bazant, Martin Z.; Joanny, Jean‐François

doi:10.1140/epje/i2008-10433-1

Cited by 62 publications

(91 citation statements)

References 48 publications

(182 reference statements)

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“…We conclude that, within error bars, the bending rigidity is not affected by the applied electric potential for the salt concentration we use in the simulations. Theory [3,10] predict a contribution much lower than k B T in accordance with our observation. Finally a note on the observed thickness.…”

Section: B With Applied Electrical Potentialsupporting

confidence: 91%

Tension moderation and fluctuation spectrum in simulated lipid membranes under an applied electric potential

Loubet

Lomholt

Khandelia

2013

The Journal of Chemical Physics

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We investigate the effect of an applied electric potential on the mechanics of a coarse grained POPC bilayer under tension. The size and duration of our simulations allow for a detailed and accurate study of the fluctuations. Effects on the fluctuation spectrum, tension, bending rigidity and bilayer thickness are investigated in detail. In particular the least square fitting technique is used to calculate the fluctuation spectra. The simulations confirm a recently proposed theory, that the effect of an applied electric potential on the membrane will be moderated by the elastic properties of the membrane. In agreement with the theory we find that the larger the initial tension the larger the effect of the electric potential. Application of the electric potential increases the amplitude of the long wavelength part of the spectrum and the bending rigidity is deduced from the short wavelength fluctuations. The effect of the applied electric potential on the bending rigidity is non-existent within error bars. However when the membrane is stretched there is a point where the bending rigidity is lowered due to a decrease of the thickness of the membrane. All these effects should prove important for mechanosensitive channels and biomembrane mechanics in general.

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Section: B With Applied Electrical Potentialsupporting

confidence: 91%

Tension moderation and fluctuation spectrum in simulated lipid membranes under an applied electric potential

Loubet

Lomholt

Khandelia

2013

The Journal of Chemical Physics

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“…Biological interfaces are however more complex, due to their strong and local dependence on the surrounding pH, and the conformational flexibility of the molecules. Correlated ionic networks are however likely to play key roles in charge transfer 12,38 and membrane shaping 58 , and both experiments and simulations are already underway to examine these possibilities.…”

Section: Discussionmentioning

confidence: 99%

Water-induced correlation between single ions imaged at the solid–liquid interface

2014

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When immersed into water, most solids develop a surface charge, which is neutralized by an accumulation of dissolved counterions at the interface. Although the density distribution of counterions perpendicular to the interface obeys well-established theories, little is known about counterions' lateral organization at the surface of the solid. Here we show, by using atomic force microscopy and computer simulations, that single hydrated metal ions can spontaneously form ordered structures at the surface of homogeneous solids in aqueous solutions. The structures are laterally stabilized only by water molecules with no need for specific interactions between the surface and the ions. The mechanism, studied here for several systems, is controlled by the hydration landscape of both the surface and the adsorbed ions. The existence of discrete ion domains could play an important role in interfacial phenomena such as charge transfer, crystal growth, nanoscale self-assembly and colloidal stability.

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“…In recent years, the same Stern boundary condition has also been used extensively in other dynamical situations with time-dependent normal currents, such as capacitive charging of blocking electrodes [24,41,54], fluctuations of ion-conducting biological membranes [57,58], induced-charge electro-osmotic flows [38], and electrofluidic gating [59]. In all of these situations, the dimensionless parameter δ controls the voltage drop across the Stern layer relative to that of the diffuse layer and has two important limiting cases [52]: (i) In the GC limit δ → 0, the Stern layer is negligible, and the diffuse layer carries all of the DL voltage, as in Gouy's model of the DL.…”

Section: B Diffuse Charge In the Dlsmentioning

confidence: 99%

Diffuse charge and Faradaic reactions in porous electrodes

2011

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Porous electrodes instead of flat electrodes are widely used in electrochemical systems to boost storage capacities for ions and electrons, to improve the transport of mass and charge, and to enhance reaction rates. Existing porous electrode theories make a number of simplifying assumptions: (i) The charge-transfer rate is assumed to depend only on the local electrostatic potential difference between the electrode matrix and the pore solution, without considering the structure of the double layer (DL) formed in between; (ii) the charge-transfer rate is generally equated with the salt-transfer rate not only at the nanoscale of the matrix-pore interface, but also at the macroscopic scale of transport through the electrode pores. In this paper, we extend porous electrode theory by including the generalized Frumkin-Butler-Volmer model of Faradaic reaction kinetics, which postulates charge transfer across the molecular Stern layer located in between the electron-conducting matrix phase and the plane of closest approach for the ions in the diffuse part of the DL. This is an elegant and purely local description of the charge-transfer rate, which self-consistently determines the surface charge and does not require consideration of reference electrodes or comparison with a global equilibrium. For the description of the DLs, we consider the two natural limits: (i) the classical Gouy-Chapman-Stern model for thin DLs compared to the macroscopic pore dimensions, e.g., for high-porosity metallic foams (macropores >50 nm) and (ii) a modified Donnan model for strongly overlapping DLs, e.g., for porous activated carbon particles (micropores <2 nm). Our theory is valid for electrolytes where both ions are mobile, and it accounts for voltage and concentration differences not only on the macroscopic scale of the full electrode, but also on the local scale of the DL. The model is simple enough to allow us to derive analytical approximations for the steady-state and early transients. We also present numerical solutions to validate the analysis and to illustrate the evolution of ion densities, pore potential, surface charge, and reaction rates in response to an applied voltage.

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Electrostatic and electrokinetic contributions to the elastic moduli of a driven membrane

Cited by 62 publications

References 48 publications

Tension moderation and fluctuation spectrum in simulated lipid membranes under an applied electric potential

Tension moderation and fluctuation spectrum in simulated lipid membranes under an applied electric potential

Water-induced correlation between single ions imaged at the solid–liquid interface

Diffuse charge and Faradaic reactions in porous electrodes

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