It has not been tested experimentally yet, but if a proposal to use graphene as a nanotech method to sequence DNA very rapidly and inexpensively pans out, the “wonder material” of nanotechnology could find yet another use. From nanotechweb.org, written by James Dacey (requires free registration) “Graphene could accelerate genomics“:
The “wonder material” graphene could soon be used to analyse DNA at a record-breaking pace. That’s the claim of a physicist in the US who has proposed a new way of reading the sequence of chemical bases in a DNA strand by sending the molecule through a tiny slit in a graphene sheet.
While the technique has yet to be verified experimentally, if successful it could be eligible for the $10 million X Prize for Genomics, which has set the challenge of developing a new rapid and low-cost sequencing technology.
…Henk Postma at California State University Northridge has proposed a way of sequencing an entire DNA strand without the need for blasting or computer processing (arXiv:0810.3035).
The technique involves cutting a very narrow slit or “nanogap” along the length of a piece of graphene — an extremely strong sheet of carbon just one atom thick. A voltage is applied perpendicular to the graphene’s surface, which causes the DNA strand to pass slowly through the slit one base at a time.
A second voltage is applied across slit and electrons are able to “tunnel” across the nanogap via the base that happens to be passing through the slit. There are four different types of base in a DNA molecule, and each should support a different tunnelling current — allowing the base type to be identified.
While the idea of sequencing DNA by sending it through a tiny gap is not new, previous schemes had relied on using separate materials for the membrane and electrodes — and aligning the two materials has proved to be a considerable challenge. Postma’s design gets around this problem by having the graphene function as both membrane and electrode.
—Jim
