Manning condensation in two dimensions

Manning condensation in two dimensions.

We consider a macroion confined to a cylindrical cell and neutralized by oppositely charged counterions. Exact results are obtained for the two-dimensional version of this problem, in which ion-ion and ion-macroion interactions are logarithmic. In particular, the threshold for counterion condensation is found to be the same as predicted by mean-field theory. With further increase of the macroio...

Manning-Oosawa counterion condensation.

Counterion condensation is a basic feature of 2D electrostatics exhibited by highly charged rodlike polymers such as DNA. In the framework of the Poisson Boltzmann equation with salt, we show that such a polymer of radius a attracts a condensate of thickness RM=A(axi)1/2 where xi is the Debye length and A depends weakly on the polymer charge density q0. To leading order in 1/ln(xi/a), we derive...

DNA condensation in two dimensions.

We have found that divalent electrolyte counterions common in biological cells (Ca(2+), Mg(2+), and Mn(2+) ) can condense anionic DNA molecules confined to two-dimensional cationic surfaces. DNA-condensing agents in vivo include cationic histones and polyamines spermidine and spermine with sufficiently high valence (Z) 3 or larger. In vitro studies show that electrostatic forces between DNA cha...

Capillary condensation between disks in two dimensions

Onsager-Manning-Oosawa condensation phenomenon and the effect of salt.

Making use of results pertaining to Painlevé III type equations, we revisit the celebrated Onsager-Manning-Oosawa condensation phenomenon for charged stiff linear polymers, in the mean-field approximation with salt. We obtain analytically the associated critical line charge density and show that it is severely affected by finite salt effects, whereas previous results focused on the no salt limi...