期刊
NANO LETTERS
卷 19, 期 8, 页码 5661-5666出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.9b02219
关键词
Nanopores; DNA nanotechnology; single-molecule sensing; ionic current
类别
资金
- Winston Churchill Foundation of the United States
- EPSRC
- Cambridge Trust
- Trinity Hall, Cambridge
- ERC [647144]
- European Research Council (ERC) [647144] Funding Source: European Research Council (ERC)
The translocation of double-stranded DNA through a solid-state nanopore may either decrease or increase the ionic current depending on the ionic concentration of the surrounding solution. Below a certain crossover ionic concentration, the current change inverts from a current blockade to current enhancement. In this paper, we show that the crossover concentration for bundled DNA nanostructures composed of multiple connected DNA double-helices is lower than that of double-stranded DNA. Our measurements suggest that counterion mobility in the vicinity of DNA is reduced depending on the three-dimensional structure of the molecule. We further demonstrate that introducing neutral polymers such as polyethylene glycol into the measurement solution reduces electroosmotic outflow from the nanopore, allowing translocation of large DNA structures at low salt concentrations. Our experiments contribute to an improved understanding of ion transport in confined DNA environments, which is critical for the development of nanopore sensing techniques as well as synthetic membrane channels. Our salt-dependent measurements of model DNA nanostructures will guide the development of computational models of DNA translocation through nanopores.
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