ELECTROHYDRODYNAMIC STRETCHING OF DNA IN CONFINED ENVIRONMENTS

The effect of confinement on the dynamics of polymers was studied by o bserving the transient extension and relaxation of single DNA molecule s as they interacted with obstacles in a specially designed thin slit. Viscous drag was found to increase with the degree of confinement, wh ich we interpret in terms of hydrodynamic screening by the planar surf aces of the slit. Since the DNA was driven by an electrophoretic force , the experimental data support the notion that an electric field acts on a tethered polyelectrolyte equivalently to a hydrodynamic flow.