In the era of Big Science, it is often assumed that cutting-edge research can't be done cheaply. Yet even now a piece of tape can lead to a Nobel prize. Andre Geim and Konstantin Novoselov got one that way, for their discovery of graphene, a type of carbon one atom thick but more than 100 times stronger than steel.
Sure, we all know graphene will lead to bendable computer screens and ultralight materials but it turns out graphene may also revolutionize genetic sequencing.
Researchers at the University of Delaware have created new approach for ultrafast DNA sequencing based on nanopores drilled into a sheet of graphene. DNA is threaded through that nanopore and then, a current of ions flowing vertically through the pore or an electronic current flowing transversely through the graphene is used to detect the presence of different DNA bases within the nanopore.
“Since graphene is only one atom thick, the nanopore through which DNA is threaded has contact with only a single DNA base,” said Branislav Nikolic, associate professor of physics and astronomy at University of Delaware. In 2010, three experimental teams—led by Jene Golovchenko of Harvard, Cees Dekker of Delft and Drndić—demonstrated DNA detection using nanopores in large-area graphene. However, Nikolic said, the process moved too quickly for the existing electronics to detect single DNA bases.
The new device concept uses graphene nanoribbons—thin strips of graphene that are less than 10 nanometers wide—with a nanopore drilled in their interior. Chemists, engineers, materials scientists and physicists have devised various methods over the past three years to fabricate nanoribbons with a specific zigzag pattern of carbon atoms along their edges, Nikolic said. Nanoribbons could enable fast and low-cost (less than $1,000) DNA sequencing, he said, because of the quantum-mechanically generated electronic currents that flow along those edges.
"We used the knowledge acquired from several years of theoretical and computational research on the electronic transport in graphene to increase the magnitude of the detection current in our biosensor by a thousand to million times when compared to other recently considered devices," Nikolic said. "Two years ago, scientists would have told me our device was impossible, but there are so many people working on graphene that nothing is impossible anymore. Every time physicists think something is impossible, materials scientists or chemists come to the rescue—and vice versa."
Nikolic said he and postdoctoral researcher Kamal Saha have employed their home-grown massively parallel computational codes to simulate the operation of the proposed nanoelectronic biosensor from first principles, using 500-1,000 processors for several months continuously.
Citation: Kamal K. Saha, Marija Drndić and Branislav K. Nikolić, 'DNA Base-Specific Modulation of Microampere Transverse Edge Currents through a Metallic Graphene Nanoribbon with a Nanopore', Nano Lett., 2012, 12 (1), pp 50–55 DOI: 10.1021/nl202870y
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