Phase behavior of semidilute polyelectrolyte mixtures of F-actin and DNA

We investigate the phase behavior of semidilute mixtures of polyelectrolyte DNA coils and F-actin rods. F-actin has a persistence length of $\sim $10 microns and a linear charge density of -1e/0.25nm. DNA has a persistence length of $\sim $50nm and a linear charge density of --1e/0.17nm. Confocal and polarized microscopy data show that actin-DNA phase separates into ribbon-like birefringent domains of nematic F-actin and a disordered mesh of DNA coils. Synchrotron Small Angle X-ray Scattering (SAXS) show that DNA compresses F-actin into an ultradense dense nematic phase. The spacing between nematic F-actin domains shows a power-law dependence on DNA concentration which is independent of the contour lenth of either DNA or F-actin.