DNA electrophoresis on a flat surface

We report a new approach for performing DNA electrophoresis. Using experime ntal studies and molecular dynamics simulations, we show that a perfectly f lat silicon wafer, without any surface features, can be used to fractionate DNA in free solution. We determine that the ability of a flat surface to s eparate DNA molecules results from the local friction between the surface a nd the adsorbed DNA segments. We control this friction by coating the Si su rface with silane monolayer films and show that it is possible to systemati cally change the size range of DNA that can be separated.