NEWS OF THE WEEK
SENSORS: System allows glucose monitors to measure other analytes ESEARCHERS HAVE devised a way to use inexpensive personal glucose meters (PGMs) to detect and measure a wide variety of substances in solution, including cocaine, biomolecules like adenosine and interferon, and metal ions like uranium. PGMs are widely used by diabetics to monitor glucose, and some cost only $10 or so. Bioanalytical and bioinorganic chemist Yi Lu of the University of Illinois, Urbana-Champaign, and postdoc Yu Xiang have now created reagent mixtures that can be used with the meters to make the devices much more useful as sensors. “There is real genius in the idea of leveraging the ultracheap, ultrafast, high-precision glucose-sensing capabilities of PGMs to analyze other analytes,” comments nanomaterials and chemical-sensing specialist Reginald M. Pe nner of the University of California, Irvine. “The word ‘innovative’ is often used, but it should be reserved for ideas like this one.” In the technique, DNAs that bind specific targets are selected from large libraries. A reagent mixture, containing target-specific DNA-invertase conjugates bound to magnetic beads, is added to a solution containing a target substance. The target binds selectively to the DNA, causing the DNA to break and release invertase. The beads are then removed from solution magnetically. When sucrose is added, the freed invertase catalyzes its breakdown, releasing glucose that a PGM can measure. The amount of target in the original sample is proportional to the amount of glucose produced. The technique could be used to quantify diverse types of analytes, from “metal ions and small organic molecules to biomolecules and even viruses or cells,” Lu
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and Xiang note (Nat. Chem., DOI: 10.1038/nchem.1092). Lu envisions that kits could be developed for each such target. “We are interested in forming a company to license and commercialize the technology,” he says. It is not that either DNA sensors or personal glucose meters “are overly surprising,” comments funtional nucleic acid expert Andrew Ellington of the University of Texas, Austin. “It is the engineering and development work done in their pairing, and showing that such a pair-
REPURPOSED Personal glucose monitors can measure invertasecatalyzed glucose production to quantify a target substance.
Target-bound DNA that has released invertase
Sample solution containing targets
DNA-invertase conjugate Magnetic bead
Target
Free invertase (with attached DNA fragment) Invertase-catalyzed sucrose hydrolysis
Sucrose
Glucose
Target quantified by glucose meter
ing can potentially have a huge impact in existing markets, that is surprising, novel, and extremely worthwhile.” “This is a major advance in practical applications of DNA-based sensing,” says Chunhai Fan of Shanghai Institute of Applied Physics, who specializes in biosensors. “It is clearly a very wise idea that so easily breaks the long-standing bottleneck in biosensor applications. I expect that this technology will be easily expanded to detection of virtually any molecular targets with a PGM.”— STU BORMAN
BIOPOLYMERS Dow and Mitsui forge ahead on joint polyolefins project in Brazil Mitsui & Co. is forming a joint venture with Dow Chemical to build a biopolymers complex in Brazil that will be integrated all the way back to sugarcane cultivation. Dow has been eyeing such a complex since 2007, when it revealed plans for a 350,000-metric-ton-per-year linear low-density polyethylene plant based on sugarcane. Brazilian sugar processor Crystalsev signed on as a partner but later dropped out. Under the new agreement, Mitsui will
make an initial investment of $200 million. The Japanese firm is buying a 50% stake in Santa Vitória Açúcar e Álcool, a Dow subsidiary that is growing 17,000 hectares of sugarcane in the Brazilian state of Minas Gerais. Later this year, the pair will start building a 240 million-L ethanol plant that will start up in the second quarter of 2013. Eventually, the companies plan to build a plant that will dehydrate the ethanol into ethylene and a polyolefins plant of undetermined size and product slate.
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Luis Cirihal, Dow’s director of renewable alternatives and business development for Latin America, says the partners may also expand into other biobased materials. “What we are pursuing today is the first step in many,” he says. The Brazilian firm Braskem started up a 200,000-metric-ton ethanol-based polyethylene plant in Brazil last year. “What is fundamentally very different about this project is that it is an integrated project versus a nonintegrated project,” Cirihal says of Dow’s effort.—ALEX TULLO
ADAPTED FROM NAT. C HE M. © 2011
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