Capillary electrophoretic separation of uncharged polymers using polyelectrolyte engines - Theoretical model

We recently demonstrated that the molecular mass distribution of an uncharg ed polymer sample can be analyzed using free-solution capillary electrophor esis of DNA-polymer conjugates. In these conjugates, the DNA is providing t he electromotive force while the uncharged polydisperse polymer chains of t he sample retard the DNA engine with different amounts of hydrodynamic drag . Here we present a theoretical model of this new analytical method. We sho w that for the most favourable, diffusion-limited electrophoresis condition s, there is actually an optimal DNA size to achieve the separation of a giv en polymer sample. Moreover, we demonstrate that the effective friction coe fficient of the polymer chains is related to the stiffness of the two polym ers of the conjugate, thus offering a method to estimate the persistence le ngth of the uncharged polymer through mobility measurements. Finally, we co mpare some of our predictions with available experimental results. (C) 2001 Elsevier Science B.V. All rights reserved.