Electrostatic Repulsion of Neutral Semipermeable Membranesстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:We consider an osmotic equilibrium between bulk solutions of polyelectrolyte bounded by semipermeable
membranes and separated by a thin film of salt-free liquid. Although the membranes are
neutral, the counter-ions of the polyelectrolyte molecules permeate into the gap and lead to a steric
charge separation. This gives rise to a distance-dependent membrane potential, which translates into
a repulsive electrostatic disjoining pressure. From the solution of the nonlinear Poisson–Boltzmann
equation, we obtain the distribution of the potential and of ions. We then derive an explicit formula
for the pressure exerted on the membranes and show that it deviates from the classical van’t
Hoff expression for the osmotic pressure. This difference is interpreted in terms of a repulsive electrostatic
disjoining pressure originating from the overlap of counterion clouds inside the gap. We
also develop a simplified theory based on a linearized Poisson–Boltzmann approach. A comparison
with simulation of a primitive model for the electrolyte is provided and does confirm the validity
of the theoretical predictions. Beyond the fundamental result that the neutral surfaces can repel,
this mechanism not only helps to control the adhesion and long-range interactions of living cells,
bacteria, and vesicles, but also allows us to argue that electrostatic interactions should play enormous
role in determining behavior and functions of systems bounded by semi-permeable membranes.