ChemWeb Newsletter

Not a subscriber? Join now.June 21, 2005


This week, the Alchemist reports on cleavable surfactants, drug-hormone combination for cancer, magnetic oxygen under pressure, single molecule transistors, and finally, does methane mean life on Mars.

Cleavable surfactant materials may be useful to textile manufacturing, biomedical diagnostics, and other applications where modifying the surface properties of liquids or solids is required, according to researchers at Sandia National Laboratory. Sandia's Scott Vaupen explains how researchers there have developed readily cleavable surfactants based on Diels-Alder chemistry. Unlike standard surfactants, these molecules can be thermally degraded and easily removed in an inexpensive, environmentally benign manner. The anionic surfactants can be used to reduce foaming in a wide range of applications but because they are degradable and easy to remove they would not present the usual environmental problems of soaps and other surfactants.

Combining hormones and conventional chemotherapy agents could be key to a new approach to treating cancer, according to British scientists. Ruth Duncan and María Vicent and colleagues realized that polymer carriers, so fashionable as backbones for chemotherapy agents, might be used to carry a hormonal drug to the target site in conjunction with a cytotoxin. The researchers believe their molecular tandem could have a synergistic effect on estrogen-dependent breast cancer. "Our polymer conjugate," says Duncan, "which is the first to combine hormone therapy and chemotherapy, proved to be significantly more cytotoxic against a line of tumor cells than a mixture of the two individual drugs in polymer form."

Putting solid oxygen under pressure leads to a phase transition that squeezes out oxygen's magnetism. Solid oxygen is the only molecularly magnetic element. At atmospheric pressure it is an anti-ferromagnetic insulator but becomes a metallic superconductor at high pressure. Now, Igor Goncharenko of the Léon Brillouin Laboratory in Saclay, France, and colleagues have put solid oxygen under 80000 atmospheres and observed it reverting to a non-magnetic material. Their findings could provide astronomers with important clues about the interiors of the so-called "gas" giants, Jupiter and Saturn. These planets are thought to have solid cores composed of insulating solids of oxygen, nitrogen, and hydrogen.

An international team has developed the first single-molecule transistor. Surface scientist Werner Hofer of the University of Liverpool and his colleagues have created a prototype molecular transistor that demonstrates how a single charged atom held on a silicon surface can regulate the conductivity of a nearby molecule. The team, which includes researchers at the National Institute for Nanotechnology of the National Research Council in Canada and the University of Alberta showed that they could control the current through a single molecule while all surrounding atoms remain neutral. The research brings science one step closer to the realm of molecular electronics, which will ultimately revolutionize computing, electronics, and telecommunications.

Would the presence of methane on Mars suggest the presence of life on the Red Planet? Two Dartmouth College researchers don't think so. Mukul Sharma and Chris Oze have weighed in on the debate by suggesting that methane could just as readily have been produced by inorganic chemical processes as by putative bacteria. "Most methane on Earth is produced by bacteria, and methane has been cited as an indicator of life on other planets," explains Sharma. However, he and Oze explain in Geophysical Research Letters, that the mineral olivine can be altered in the presence of water and carbon dioxide to produce copious quantities of methane. "It's quite easy to do, and there is nothing bacterial about it. If there is life on Mars, I would like to see better evidence than methane," says Sharma.