Dielectric-induced counterion partitioning and its effect on membrane rigidity.

We report on a nonthermal mechanism for counterion partitioning driven by dielectric contrasts in a charged system. This mechanism allows objects to remain charged even in very low dielectric mediums and at low temperatures, if a nearby high dielectric environment can host its counterions. This nonthermal counterion partitioning leads to an attractive counterion pressure that is usually much larger than the van der Waals forces. In the context of a lipid membrane, this partitioning will stiffen the membrane by approximately k(B)T.