Publications

We studied the phase behavior of a mixture of two semi-flexible negatively-charged polyelectrolytes, giant DNA and alginate, under crowded condition in a cell-sized sphere (5-40 μm in diameter), where the persistence length of giant DNA is 50 nm and that of alginate is 5 nm. Through microscopic observation, we found that the polymer mixture exhibits a unique phase behavior, which depends on the size of the sphere, whereas the mixture remains homogeneous/isotropic in bulk solution. When the sphere is small, DNA is completely depleted on the surface. When the sphere is medium-sized, a portion of the DNA is depleted on the surface, and the remainder stays within the sphere. By introducing a curvature-dependent term for the interaction between DNA and the surface into the Flory-Huggins model, we interpret the observed characteristics of the phase behavior in terms of the relative importance of the surface-to-volume effect.