title: Bilayer-spanning DNA nanopores with voltage-switching between open and closed state.
abstract: Membrane-spanning nanopores from folded DNA are a recent example of biomimetic man-made nanostructures that can open up applications in biosensing, drug delivery, and nanofluidics. In this report, we generate a DNA nanopore based on the archetypal six-helix-bundle architecture and systematically characterize it via single-channel current recordings to address several fundamental scientific questions in this emerging field. We establish that the DNA pores exhibit two voltage-dependent conductance states. Low transmembrane voltages favor a stable high-conductance level, which corresponds to an unobstructed DNA pore. The expected inner width of the open channel is confirmed by measuring the conductance change as a function of poly(ethylene glycol) (PEG) size, whereby smaller PEGs are assumed to enter the pore. PEG sizing also clarifies that the main ion-conducting path runs through the membrane-spanning channel lumen as opposed to any proposed gap between the outer pore wall and the lipid bilayer. At higher voltages, the channel shows a main low-conductance state probably caused by electric-field-induced changes of the DNA pore in its conformation or orientation. This voltage-dependent switching between the open and closed states is observed with planar lipid bilayers as well as bilayers mounted on glass nanopipettes. These findings settle a discrepancy between two previously published conductances. By systematically exploring a large space of parameters and answering key questions, our report supports the development of DNA nanopores for nanobiotechnology.
authors.affiliation: Nanion Technologies GmbH , D-80636 Munich, Germany.
authors.forename: Astrid
authors.initials: A
authors.lastname: Seifert
authors.forename: Kerstin
authors.initials: K
authors.lastname: Göpfrich
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Burns
authors.forename: Niels
authors.initials: N
authors.lastname: Fertig
authors.forename: Ulrich F
authors.initials: UF
authors.lastname: Keyser
authors.forename: Stefan
authors.initials: S
authors.lastname: Howorka
mesh_terms: D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D004247:DNA / Q000737:chemistry*; D004553:Electric Conductivity; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D008968:Molecular Conformation; D058608:Nanopores; D011092:Polyethylene Glycols / Q000737:chemistry
chemical_list: D008051:Lipid Bilayers; D011092:Polyethylene Glycols; D004247:DNA
keywords: DNA nanotechnology; PEG; bilayer membrane; nanofluidics; nanopore; single-molecule