Electrophoretic manipulation of single DNA molecules in nanofabricated capillariesElectronic supplementary information (ESI) available: Four videoclips showing the movement of DNA molecules in nanocapillaries. See http://www.rsc.org/suppdata/lc/b3/b312592k/

We demonstrate the use of nanofabricated capillaries, integrated as part of a microfluidic structure, to study the electrophoretic behaviour of single, fluorescently-labelled, molecules of DNA as a function of capillary size. The nanocapillaries, fabricated using a focused ion beam, have cross-sections down to 150 x 180 nm. Control of single-molecule direction and velocity was achieved using voltage manipulation. DNA mobility was found to increase with decreasing cross-section, which we interpret in terms of reduced electro-osmotic counter-flow. Such nanofabricated capillaries as part of larger fluidic structures have great potential for biotechnology, particularly single molecule manipulation and analysis.