The ion permeability of DNA nanotube channels

Techniques from structural DNA nanotechnology make it possible to assemble complex 3-dimensional nanostructures with virtually arbitrary control over their sizes, shapes and features at length scales of 3-100 nm, providing a flexible means for constructing nanoscale devices and machines. Here, we assemble micron-length DNA nanotubes and assess their performance as pipes for controlled ion transport. DNA nanotubes grow via assembly of DNA tiles from a seed pore, a 12-helix DNA origami cylinder functionalized with cholesterol, to form a DNA nanotube channel. The central channel of a nanotube can be obstructed via Watson-Crick hybridization of a channel cap, a second DNA origami structure, to the end of a nanotube channel or a nanotube seed pore. Single-channel electrophysiological characterization shows that both nanotube seed pores and nanotube channels display ohmic ion conductance consistent with their central channels diameters. Binding of the channel cap reduces the conductances of both DNA nanotube channels and seed pores, demonstrating control of ion-transport through these micron-length channels. Because these channels could be assembled into branched architectures or routed between specific molecular terminals, these results suggest a route to self-assembling nanofluidic devices and circuits in which transport can be controlled using dynamic biomolecular interactions.