May 1, 2009

2 Min Read
Going Gaga Over Graphene


Move over, silicon: A new wunderkind in the materials world has stolen the spotlight.

Just discovered in 2004, graphene is a one-atom-thick sheet composed of carbon arranged in a honeycomb-like lattice. Although new to us, graphene has actually been around for a long time: Stacked sheets of graphene comprise graphite, the material from which pencils are made. And while pencils are well and good for graphite, much bigger applications may be in store for graphene.
Referred to in some circles as 'the new silicon,' graphene is low cost and easy to work with. It also boasts a flexible structure, high optical transparency, and significant mechanical strength. The material's appeal, however, is rooted in its superior electrical and thermal conductivity. Graphene's electrical conductivity is 100 times faster than that of silicon, while its thermal conductivity ranges from 3500-5300 W/mK, compared with 130 W/mK for silicon, notes Vikas Berry, an assistant professor of chemical engineering at Kansas State University.
Equipped with these inherent properties, graphene has been the subject of much excitement regarding its potential to revolutionize such sectors as electronics and semiconductors. Garnering less attention, sadly, is its potential in medical applications, which could, in fact, be sizable.
The material shows particular promise for biomedical sensing applications. "Graphene's microscale surface area can be used for biointerfacing with cellular components, while its nanoscale quantum-confinement imparts it a high electronic sensitivity," explains Berry. "With the electrons restricted to move in a single-atom-thick sheet, any small interference from the outside world brings a sensitive change in graphene's electrical properties."
This sensitivity inspired Berry's team to examine the idea of a graphene-based DNA sensor upon noticing that electrons in graphene tethered with DNA change their speed if complementary DNA binds to it. The concept of a bacteria-operated battery engineered from wrapping graphene around electron-producing bacteria is also being discussed. Berry cautions, however, that more research is necessary to determine how molecules interface with graphene. The toxicity of graphene is unknown as well.
Composite materials, namely graphene oxide, also demonstrate potential. A Stanford University research group, for example, has shown that it is photoluminescent in the visible and infrared regions of the electromagnetic spectrum. This revelation indicates that graphene oxide could be used for in vivo imaging. The researchers also think that the material could transport cancer therapies, a discovery that could pave the way for simultaneous cancer cell imaging and treatment.
Researchers have only begun to scratch the surface of graphene's potential, despite the fact that this nanoscale component of graphite has been right under our noses--or in our hands--for ages. But if even a fraction of these hypotheses become realities, graphene could open up a world of possibilities. The writing's on the wall: pencil in some time to get to know graphene--it may just be worth it.
Shana Leonard
Copyright ©2009 Medical Product Manufacturing News

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