A theory for the electrophoretic separation of DNA in polymer solutions

We present a mathematical model of DNA capillary electrophoresis in polymer solutions based on nonentangling collisions between DNA and polymer molecu les. Using videomicroscopy images of DNA migrating through polymer solution s, we propose a modified transient entanglement coupling mechanism for DNA separations that includes nonentangling DNA/polymer collisions. We show tha t a mathematical model based on individual nonentangling DNA/polymer collis ions is able to predict the mobilities of DNA in solutions of low molecular mass polymer. We compare the model predictions to mobility data for separa tions of DNA in a range of concentrations for solutions of both hydroxyprop ylcellulose (M-w 100 000) and hydroxyethylcellulose (M-w 139 000). The mode l relies on one fitted parameter, the time constant for the interaction bet ween the DNA and polymer molecules, which is based on the physical properti es of DNA and polymers.