Semiflexible polymer condensates in poor solvents: toroid versus spherical geometries

Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Mar;71(3 Pt 1):031802. doi: 10.1103/PhysRevE.71.031802. Epub 2005 Mar 14.

Abstract

Semiflexible polymers, such as DNA, in the presence of a condensing agent often form toroids. This is due to a balance between bending and surface area free energy penalties. Here we show why in experiments all the toroids have been found to have similar physical size. We also introduce a novel morphology, that of the hollow sphere, which is favored for long polymer chains. This offers the possibility of encapsulating material inside a "vesicle" made of semiflexible polymers. We also consider the case of many such polymer chains placed in a poor solvent. We show a transition between two morphologies occur on increasing concentration of polymer chains, from a thickened toroid to a spherical globule.