Synthetic Lipid Membrane Channels formed by Designed DNA Nanostructures

Abstract

Scaffolded DNA origami was used to create a synthetic membrane channel that consists of a hollow stem that penetrates and spans a lipid bilayer membrane, and a barrel-shaped cap that adheres to the membrane via cholesterol moieties. Transmission electron microscopy was used to confirm that the intended shape is realized and that the synthetic DNA channels bind to lipid membranes in the desired orientation. The conductance of the resulting membrane pores was studied in electrophysiological experiments. Successful membrane incorporation of individual synthetic DNA channels manifested itself in a stepwise increase in transmembrane current and an increase in electrical noise. The DNA channels displayed an Ohmic conductance of ∼ 1nS per channel in 1M KCl, which agrees with expectations based on the channel geometry. Similar to naturally occurring ion channels, the synthetic DNA channels display gating behavior, which may be caused by thermal fluctuations of the structure. Gating behavior is found to differ significantly for different variants of the channel. Geometry and chemical properties of DNA channels can be tailored for custom nanopore sensing applications. We also demonstrate that the channels can be used for single molecule studies of DNA secondary structures.View Large Image | View Hi-Res Image | Download PowerPoint Slide