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 micrometer-long 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 18 cholesterol anchors, to generate 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, clamped to its end. The single-channel electrical recordings show 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, indicating that ion transport can be modulated and measuring the resulting residual transport through DNA-wall gaps or DNA-lipid interfacial pathways. Our findings help design self-assembling nanofluidic devices and circuits in which transport may be regulated via dynamic biomolecular interactions, since these channels could be constructed into branched topologies or routed between specific molecular terminals.