Ion Transport Through Large-Diameter DNA Origami Nanotube Channels Across Synthetic Membranes

Abstract

Transport through nanoscale channels is a fundamental mechanism of exchange in living systems. The ability to direct such transport using membrane-based synthetic devices could make it possible to systematically study or control these transport processes. Techniques from structural DNA nanotechnology have recently made it possible to emulate the structural and functional aspects of naturally occurring membrane channels using easy-to-design DNA nanostructures. We have designed a system for controlled transport that begins with ∼10 nm-diameter DNA origami structures that forms pores in synthetic membranes. These DNA origami structures also serves as nucleation sites for DNA tile nanotubes that can grow to many microns in length, making it possible to study nanofluidic transport within extended self-assembled biomolecular channels. The DNA origami pores spontaneously insert into membranes formed using the droplet interface bilayer technique. Single-channel electrophysiological measurements indicate that these pores have ohmic conductances in the range of 1.0-1.2 nS. DNA nanotubes growing from the origami pore extend channel length without changing channel architecture produced channels with larger conductances. An artificial DNA origami shutter that when bound to the DNA origami pore closes off the internal diameter halves the channel's conductance. Our work thus demonstrates that DNA nanostructures several microns in diameter form channels in membranes and further how the transport ions across DNA origami nanostructures can be modulated by a DNA origami structure that serves as a shutter complex.