Figure 18.

Reversal of the electrophoretic motion of DNA in a multivalent electrolyte. (a) Setup of MD simulations. The two strands of a DNA duplex are shown using a molecular surface representation, spermidine molecules directly bound to the grove of DNA are shown using vdW spheres, spermidine molecules dissolved in solution are shown using a ball-and-stick model. Subject to electric field, the DNA molecule moves through the nanochannel (gray molecular surface). (b) Center-of-mass displacement of the DNA duplex versus simulation time at three different concentrations of spermidine counterions. The data were taken from Ref. 182.