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. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=84 SRC="FIGDIR/small/734429v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@14e2829org.highwire.dtl.DTLVardef@2ebc37org.highwire.dtl.DTLVardef@46d16forg.highwire.dtl.DTLVardef@1600c19_HPS_FORMAT_FIGEXP M_FIG C_FIG