(411d) DNA Structure, Dynamics and Electrophoresis in the Presence of Crowding Agents

In the past decade, single molecule microscopy has emerged a valuable technique for studying the conformation and dynamics of model polymer systems such as DNA. The ability to visualize single molecules gives new insight into polymer rheology and separation processes. To date, the majority of work has focused on DNA in good solvents, such as the buffer solutions that are commonly in electrophoresis. A few studies have examined the effects of modulated ionic conditions, but these still remain in the good solvent regime. Here we explore the role of added crowding agents which give rise to attractive depletion interactions among DNA segments. We explore the change of DNA size, equilibrium dynamics (diffusivity and relaxation times) and non-equilibrium stretching dynamics in elongational electric fields. New regimes are encountered in all cases and scaling theories developed to explain them.