Attractive Interaction between Fully Charged Lipid Bilayers in a Strongly Confined Geometry

Abstract

We investigate the interaction between highly charged lipid bilayers in the presence of monovalent counterions. Neutron and X-ray reflectivity experiments show that the water layer between likecharged bilayers is thinner than for zwitterionic lipids, demonstrating the existence of counterintuitive electrostatic attractive interaction between bilayers. Such attraction can be explained by taking into account the correlations between counterions within the Strong Coupling limit, which falls beyond the classical Poisson-Boltzmann theory of electrostatics. Our results show the limit of the Strong Coupling continuous theory in a highly confined geometry and are in agreement with a decrease in the water dielectric constant due to a surface charge-induced orientation of water molecules. * Electronic address: thierry.charitat@ics-cnrs.unistra.fr arXiv:1910.09611v2 [cond-mat.soft]

Interaction between like-charged surfaces in water: does mean-field (Poisson Boltzmann) always apply for monovalent counterions?

“…Schlaich et al's work offers analytical tools for a quantitative interpretation of experiments on (polar) like-charged surfaces with monovalent counterions in water, which deserve to be widely used in the future. Similar numerical work on surfaces that can afford a higher charge density should evidence attraction induced by electrostatics as detected in experiments [6,7].…”

“…It offers much more than suggested by the, unavoidably reductive, title. This comment presents some of Schlaich et al's results in relation to a posterior experimental paper on deposited bilayers [6] and a much older one on biliquid foams [7].…”

“…It is commonly accepted that it cannot under usual experimental conditions, but what about surfaces at nanometric separations, a situation also relevant to biological systems? Two experiments [6,7] suggest that it can. In the experiment by Mukhina et al the structure of two deposited bilayers is studied by neutron and X-ray reflectivity.…”

Strong-coupling theory of counterions with hard cores between symmetrically charged walls

“…This yields an effective salt-free system, as addressed in the present work. Besides, in severely confined configurations, the modification of the solvent (say water) dielectric constant should also be included in the description [13,72].…”

Vesicle adhesion in the electrostatic strong-coupling regime studied by time-resolved small-angle X-ray scattering

“…Recently, strong coupling has been studied between two highly charged solid-supported lipid bilayers in the presence of monovalent counter-ions by neutron and X-ray reflectivity. 22 While interesting aspects of bilayer interactions beyond linear electrostatics were elucidated, studies of ion-induced transition, non-equilibrium effects or the kinetics of vesicle phase transitions still remain scarce, with the exception of experiments based on temperature changes (T-jump). 23 In this work, we now extend our SAXS studies of the adhesion state, presenting a wider range of ions and first time-resolved studies monitoring the transition from SUVs to MLVs as illustrated in Fig.…”