PURIFYING NANOTUBES
methane plasma reaction selectively adds hydrogen and methyl groups to metallic nanotubes, which are slightly more reactive than semiconducting nanotubes. Annealing the material under vacuum leaves behind only pristine semiconducting SWNTs. MATERIALS SCIENCE: Plasma process "The process is efficient, effective, and compatible selectively destroys metallic tubes with semiconductor fabrication methods," Dai says, although he points out that fine-tuning the conditions is key to the selectivity. Furthermore, the process nar rows the semiconducting nanotubes' size distribution ETALLIC SINGLE-WALLED carbon nanobecause the plasma reacts with both types of SWNTs tubes (SWNTs) can be selectively etched and if their diameters measure less than 1.4 nm. Presum eliminated from a substrate without damag ably, the greater curvature makes the semiconducting ing their semiconducting SWNT neighbors, thanks to a finely tuned methane plasma reaction (Science 2006,314, SWNTs more reactive. 974). The process, developed by scientists at Stanford "The technique is important, in part, because it has University, is getting attention from chip makers for its the potential to advance efforts that seek to use dense, potential in manufacturing nanotube-based electronics. aligned arrays of nanotubes as effective thin-film semi To date, all SWNT syntheses inevitably produce a conductors for scalable, ultra-high-performance elec mixture of both semiconducting and metallic nanotronics," comments John Rogers, a chemistry professor tubes, which differ in their architecture and proper at the University of Illinois, Urbana-Champaign. ties. This mix has been the primary roadblock to using George Griiner, a physics professor at the University SWNTs in high-performance electronic devices. Me of California, Los Angeles, thinks the process will be im tallic SWNTs will short-circuit electrical devices, and portant for emerging plastic electronic applications. He so far, there's no simple way to separate the different does, however, point out that 'further innovative steps types of tubes. are needed before single-nanotube devices with adequate reproducibility can be made."-BETH AN Y H ALFORD Hongjie Dai and coworkers report that a gas-phase
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ABBOTT TO BUY KOS BUSINESS: $3.7 billion acquisition is targeted at the lipid management market
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BBOTT LABORATORIES has agreed to acquire the specialty drugmaker Kos Pharmaceuticals for $3.7 billion. Kos, based in Cranbury, N.J., sells products designed to manage levels of "good" and "bad" cholesterol. Abbott CEO Miles D. White says the purchase will expand his firm's presence in the field known as lipid management, a $20 billion-per-year market dominated by Pfizer's statin drug Lipitor. Kos's two main products are Niaspan and Advicor. Niaspan, launched in 1997, is an extended-release form of the vitamin niacin, which raises levels of high-den sity lipoprotein (HDL), or good cholesterol. Four-yearold Advicor combines Niaspan with lovastatin, the first in the statin class of drugs, which lower low-density lipoprotein, or bad cholesterol. These and other products brought in sales last year of $752 million, a 51% increase over 2004 sales. Kos's
drug pipeline holds a new Niaspan formula, now under FDA review, that reduces the facial flushing associated with niacin. Also in development is Simcor, a combination of Niaspan and simvastatin, the active ingredient in Merck's statin drug, Zocor. Kos expects to submit Simcor for FDA re view next year. With the purchase, Ab bott is looking to build on its success with the lipid man agement drug TriCor, a Solvay product that Abbott markets in the U.S.; sales last year were $927 million. In July, Abbott and AstraZeneca announced plans to de velop a new combination product that joins AstraZeneca's statin drug, Grestor, with either TriCor or ABT-335, an HDL-raising drug that Abbott is developing. Robert Hazlett, a stock analyst with BMO Capital Markets, is bullish on the Abbott-Kos combination despite stiff competition from the likes of Merck and Pfizer. "We believe Abbott's success with TriCor bodes well for its potential with the Niaspan franchise," he wrote in a note to clients.—MICHAEL MCCOY
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NOVEMBER 13, 2006
< Metallic (top) and semiconducting (bottom) nanotubes.
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