Charge-Fluctuation-Induced Non-analytic Bending Rigidity

TL;DR

This paper investigates how charge fluctuations on curved surfaces influence membrane bending rigidity, revealing a non-analytic, logarithmic dependence that can induce spontaneous vesicle formation.

Contribution

It introduces a model showing charge fluctuations cause a non-analytic, logarithmic correction to bending rigidity on curved membranes, explaining vesicle formation phenomena.

Findings

Charge fluctuations add a non-analytic, logarithmic term to bending rigidity.

The effect can lead to spontaneous vesicle formation.

The model applies to charged membranes and surfactant mixtures.

Abstract

In this Letter, we consider a neutral system of mobile positive and negative charges confined on the surface of curved films. This may be an appropriate model for: i) a highly charged membrane whose counterions are confined to a sheath near its surface; ii) a membrane composed of an equimolar mixture of anionic and cationic surfactants in aqueous solution. We find that the charge fluctuations contribute a non-analytic term to the bending rigidity that varies logarithmically with the radius of curvature. This may lead to spontaneous vesicle formation, which is indeed observed in similar systems.