Size-dependent DNA mobility in nanochannels

Nanofluidic slits are used to investigate surface interactions during electrophoresis between DNA molecules and channel walls. The channels have vertical dimensions of 19 and 70 nm and contain no sieving matrix. Size-dependent mobility is observed for DNA in the 19 nm channels. We present a model for double stranded DNA mobility in the nanochannels that accurately predicts the size dependence of the DNA mobility in the range of 2000-10 000 bp. Due to surface interactions, the DNA mobility in the nanochannels scales as N-1/2. These results suggest that the notion of free solution DNA electrophoresis breaks down due to surface interactions in nanoscale environments.