ChemWeb Newsletter

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In this week's Alchemist, testing times for tequila, spotting tumorsusing nanoparticles, and having the stomach for bacterial receptors.Also under the torchlight, new elemental discoveries, and bringingnitrogen into the search for ET.

Researchers in Mexico and Germany have devised a quality assuranceprocedure that can distinguish between the real thing and faux tequilamanufactured by fraudulent sources or using non-genuine startingmaterials. The findings provide a new shot of QC to the billion-dollartequila market. The team used ion and gas chromatography together withFourier Transform Infrared Spectroscopy (FTIR), to obtain the chemicalfingerprints of genuine tequila. These fingerprints then allow them toidentify adulterated or mixed-tequila that is made with processed sugarrather than the Agave plant. The researchers explain that combiningspectroscopic and chromatographic methods provides a more accurateidentification than previous attempts that focused on other chemicals orisotopic analysis. The same test works with other Agave spiritsincluding including mezcal, sotol and bacanora.

Enzymes that can flip the magnetic properties of iron oxidenanoparticles could provide oncologists with a way to image tumorsalmost as quickly and easily as radiologists view broken bones withX-rays. Sangeeta Bhatia in Boston, Massachusetts and colleagues at theHarvard-MIT Division of Health Sciences and Technology have found thatthe aggregation properties of Fe3O4 nanoparticlescan be used as a novel imaging agent in magnetic resonance imaging. Theycoated one half of a sample of the nanoparticles with the protein biotinand the other with neutravidin. They then added peptide-attached PEG asa protecting group to the proteins to prevent them sticking togetherspontaneously. The peptide anchor is cleaved only by the action of atumor-specific enzyme, matrix metalloproteinase-2 (MMP-2). Thenanoparticles can thus float freely until they reach a tumor, MMP-2 thencleaves off the protecting groups, leaving the biotin and neutravidinfree to bond. Once this occurs the nanoparticles form significantclusters visible to MRI, allowing a precise picture of the tumor's shapeto be obtained.

Researchers at Vanderbilt University have discovered the receptor thatallows the corkscrew-shaped bacteria Helicobacter pylori toattach to the lining of the stomach. The findings could provide a newtarget for eradicating an infection without the need for an antibioticcocktail. H. pylori infects the mucus lining of the stomach andis a leading cause of peptic ulcers and gastric cancer. Infection iswidespread in the West but even more so in developing nations where upto 80% of children and 90% of adults are thought to carry H.pylori. Vanderbilt's Richard Peek and colleagues have now confirmedthat the membrane-embedded protein, decay-accelerating factor (DAF),which is a known receptor for several bacterial pathogens, is alsoinvolved in H. pylori adherence. New drugs that interfere withDAF binding could prevent or treat peptic ulcer disease or distalgastric adenocarcinoma.

The Periodic Table is deceptively simple. However, its apparentsimplicity harbors a dark secret: we do not yet understand how all theelements it contains in its rank and file were first formed. Now, aEuropean-led team has examined models of a supernova's earliest momentsto try and fill our periodic knowledge gap. Carla Fröhlich of theUniversity of Basel, Switzerland, and colleagues have found that protonsin the proton-rich region surrounding a freshly formed neutron star,which lasts just seconds, can transform into neutrons by reacting withantineutrinos streaming from the neutron star. These extra neutrons arecritical during this period when the material is still hot enough tomake heavy, proton-rich isotopes, as nuclei packed with their fill ofprotons can grab these new neutrons. In so doing, they generate enoughbinding force to capture yet another proton shifting up the periodictable as they go. The work could explain the origins of isotopes of themetals molybdenum and ruthenium, which are proton heavy and contained inthe sun and meteorites, but have no clear origin in accepted nuclearreactions.

Geobiologists at the University of Southern California reckon that thenarrow search for water could miss important clues to extraterrestriallife. They suggest the search should be widened to look for signs oforganic nitrogen as a direct indicator of life, because nitrogen isessential to the chemistry of living organisms. "It's hard to imaginelife without water," says Kenneth Nealson, "but it's easy to imaginewater without life." On the other hand, the discovery of nitrogen onMars, for instance, would be a different story. "If you found nitrogenin abundance on Mars, you would get extremely excited because itshouldn't be there," Nealson adds. Unlike carbon, nitrogen is not amajor component of minerals, so the presence of any substantial organicnitrogen deposits in the Martian soil would have almost certainly haveresulted from biological activity.