DNA: A Nanoscale Archimedes' Screw

Rotating helices have been utilized for many purposes, including the transport of solid material and fluids within man-made machines for a little over two millennia. Here, we show that the rotation of a biological helical molecule─a DNA duplex─can move water and ions through a nanoscale pore. While the rotation-induced flow of water is generated by the steric shape of the DNA molecule, an even faster transport of cations is caused by electrostatic interactions. The rotation-induced ion flux is found to depend on the cation type, offering potential utility for ion separation. Finally, we show that the torque-driven duplex can move ions against a concentration gradient, realizing the Archimedes screw principle at the nanoscale.