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Analytical Chemistry

Graphene Nanogaps For DNA

A narrow gap in a graphene sheet attached to gold electrodes has been proposed as a means to sequence DNA

by Celia Henry Arnaud
January 18, 2010 | A version of this story appeared in Volume 88, Issue 3

Credit: Nano Lett.
Single-stranded DNA moves through a nanogap in a graphene sheet.
Credit: Nano Lett.
Single-stranded DNA moves through a nanogap in a graphene sheet.

Solid-state and protein nanopores are of great interest for DNA sequencing because of the possibility of reading longer stretches of DNA. But nanopores have trouble achieving single-base resolution. In a theoretical study, Henk W. Ch. Postma of California State University, Northridge, suggests a variation on the nanopore concept—graphene nanogaps. Postma proposes using a narrow gap in a graphene sheet attached to a pair of gold electrodes to measure the transverse conductance of DNA (Nano Lett., DOI: 10.1021/nl9029237). Each base has a characteristic conductance, and graphene’s single-atom thickness should make it possible to achieve single-base resolution during sequencing. The nanogap needs to be large enough for single-stranded DNA to slide through, but it can’t be larger than 1.6 nm. “For every 0.1-nm increase in width, the current decreases by about an order of magnitude,” Postma says. He proposes measuring the conductance with nonlinear current-voltage analysis, which would allow determination of whether current changes are due to gap-width variations or due to different bases. Postma’s calculations suggest that graphene nanogaps up to 1.6 nm will lead to error-free sequencing.


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