Persistent Draining Crossover in DNA and Other Semi-Flexible Polymers: Evidence from Hydrodynamic Models and Extensive Measurements on DNA Solutions
Jack F. Douglas, Marc Mansfield
Although the scaling theory of polymer solutions has had many successes, this type of argument is deficient when applied to hydrodynamic solution properties. Since the foundation of polymer science, it has been appreciated that measurements of polymer size from diffusion, sedimentation, and solution viscosity measurements reflect a convolution of effects relating to polymer geometry and the strength of the hydrodynamic interactions within the polymer coil, i.e., draining. We study this problem by examining the hydrodynamic properties of duplex DNA in solution over a wide range of molecular masses both by hydrodynamic modeling using a numerical path-integration method and by comparing with extensive experimental observations for these properties. We also considered how excluded volume interactions influence the solution properties of DNA. Our results confirm that excluded volume interactions are rather weak in duplex DNA in solution so that that the simple worm-like chain model without excluded volume gives a good leading-order description of DNA for a large range of molar masses. It is thus inappropriate to model DNA as a flexible self-avoiding polymer, except at ultra-high masses or low salt conditions. Modeling and measurements both indicate that draining effects are quite large in this class of molecules. Polymer size ratios related to polymer topology, such as ring formation or chain branching, should also exhibit a strong mass variation and deviate substantially from scaling theory expectations based on the assumption of infinite non-draining random coil chains.
and Mansfield, M.
Persistent Draining Crossover in DNA and Other Semi-Flexible Polymers: Evidence from Hydrodynamic Models and Extensive Measurements on DNA Solutions, Journal of Chemical Physics
(Accessed June 3, 2023)