ChemWeb Newsletter

Not a subscriber? Join now.January 23, 2007


This week, The Alchemist ponders the idea of an explosive squid to improve airport security and landmine detection, the discovery that bog standard calcium chloride can prevent acrylamide formation during frying, and the effects of another small molecule, dichloroacetate, on cancer tissues. Also in this week's issue, we hear how a "walking" molecule can now carry a load. Finally, Harvard chemists can now print an inexpensive diagnostic device on to a sheet of paper for testing malaria and other diseases common in the developing world.

A new detection method for spotting explosives in luggage and finding landmines has been developed by Hideo Itozaki of Osaka University and colleagues. The method relies on the different nuclear quadrupole resonances (NQR) of nitrogen in different materials, including explosives, such as trinitrotoluene, TNT. Because it utilises radio waves rather than X-rays it could provide a safer method of screening airport baggage and other risks. But, more crucially, it can distinguish between different types of powder, say, identifying flour, salt, drugs, and explosives differently. In landmine detection it could replace conventional metal detectors and easily distinguish between chunks of metal in the ground and a mine. The researchers have developed a SQUID (superconducting quantum interference device) that can detect the very low resonant frequencies of nitrogen, something that was not possible previously.

A well-known food additive (calcium chloride, E509 in Europe) could block the formation of potentially carcinogenic acrylamide in fried and baked food, according to Vural Gokmen and Hamide Senyuva, of Hacettepe University and the Scientific and Technical Research Council of Turkey, writing in the journal Food Chemistry. Acylamide first hit the headlines in 2002, when Swedish scientists reported unexpectedly high levels in cooked carbohydrate-rich foods, such as French fries, potato chips, and bread. The team dipped chipped potatoes in calcium chloride solution at room temperature for an hour and then fried them in oil for five minutes. Acrylamide levels were significantly reduced. The Maillard reaction responsible for color and flavor of French fries took place on the surface but without acrylamide formation, the researchers say.

Evangelos Michelakis of the University of Alberta and his colleagues have demonstrated that a small, "non-toxic" molecule, dichloroacetate, DCA, can kill various cancer cell lines and to shrink lung, breast and brain tumors in animal and human cancer tissues. Such a small molecule offers significant benefits in terms of low manufacturing costs, but no one has a patent on this molecule and so it could be shelved for lack of commercial viability, unless the industry can be persuaded of its worth despite this.

Two years ago, UC Riverside's Ludwig Bartels announced a molecule that can move in a straight line on a flat surface. Now, he and his colleagues have turned their molecular walker into a pack mule by adding CO2 material panniers either side. The new molecule carrier runs on a copper surface. It can pick up and release up to two carbon dioxide (CO2) molecules and carry them along its straight path. Such nanoscale devices will be as important to future technology as conveyor belts are to the industry of today. Bartels cautions, however, that this research is still in its infancy. "In 2005 we invented the molecular walker, which moves in a straight line rather than hopping around in all directions as a normal molecule would do. Now it can carry a load." Bartels explains that the continuing evolutionary process will take some time.

Soft lithography pioneer George Whitesides of Harvard University and his colleagues have developed yet another approach to small-scale chemistry. They have found they can print a diagnostic assay device on to a sheet of paper using commercially available photoresist instead of ink in their printer. The photoresist is polymerised under UV light to produce hydrophobic channels into which diagnostic reagents and sample solution can be fed. Whitesides says the team is endeavoring to make the cheapest possible bioassay for use in the developing world to allow health monitoring, of malaria, for instance to be carried out for minimal cost.