Wednesday, 30 October 2013

Through a nanopore, ionically: Graphene quantum transistor for next-generation DNA sensing

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(Phys.org) —In the ongoing quest to devise faster, lower-cost methods for sequencing the human genome, scientists at University of Illinois at Urbana–Champaign have developed a novel approach: DNA molecules are sensed by passing them through a layer of constricted graphene embedded in a solid-state membrane containing a nanopore (a small hole with a roughly 1 nm internal diameter), located in a graphene nanoribbon (GNR). A critical feature of the new paradigm is that graphene's electrical properties allow the layer to be tuned in several distinct ways – namely, altering the shape of its edge, carrier concentration and nanopore location – thereby modulating both electrical conductance and external charge sensitivity. The researchers found that their novel technique can detect the DNA strand's rotational and positional conformation, and demonstrated that a graphene membrane with quantum point contact geometry exhibits greater electrical sensitivity than on with so-called uniform armchair geometry. The team has proposed a graphene-based field-effect transistor-like device for DNA sensing.



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