ChemWeb Newsletter

Not a subscriber? Join now.April 11, 2006

contents
overview

ChemWeb's Alchemist discovers this week that polymerase can do the hula for nanotech and that a detached approach to flexible semiconductor membranes is totally tubular. Also this week, we report on an alternative supply for shikimic acid to make the flu drug, oseltamivir and how new light has been shed on the origin of life. Finally, we hear a fairytale of washing machines and golden fabrics.




Yet another chance to use DNA as the material of choice in nanotechnology has been unraveled by Canadian researchers Michael Brook, Yingfu Li, and their colleagues at McMaster University, Ontario. The team has successfully produced periodic three-dimensional nanostructures from long single strands of DNA attached to gold nanoparticles. The secret lies in "rolling circle amplification" or the "hula-hoop" technique in which a particular polymerase enzyme duplicates a DNA strand and carries on working, separating the fresh double helix and making new copies without interruption. The researchers see nanocomputers, nanocircuits, and highly sensitive biosensors as potential areas of application.





A method for releasing thin membranes of semiconductor materials from a substrate and transferring them to a new surface has been devised by US researchers. According to Michelle Roberts and colleagues at the University of Wisconsin-Madison, this advance could allow the incredibly diverse and useful properties of silicon and many other materials, such as diamond, metals and polymers to be combined. Writing in the April 9 issue of Nature Materials, Roberts explains how the detached membranes, just tens of nanometers thick, retain the properties of a conventional semiconductor wafer but gain flexibility. By varying the thicknesses of silicon and silicon-germanium layers, he explains, it is possible to fashion the membranes into curved and even tubular structures.





US chemists have found that seeds of the sweetgum fruit - gumballs - contain significant quantities of shikimic acid and could add to seasonal supplies of the seeds of the star anise fruit from which this material is usually sourced. Thomas Poon of the W.M. Keck Science Center at The Claremont Colleges in California says, "Our work gives the hearty sweetgum tree another purpose, one that may help to alleviate the worldwide shortage of shikimic acid." Shikimic acid is the starting material for flu drug oseltamivir, Tamiflu, of which adequate supplies could be critical in coping with a putative avian influenza epidemic.





Controversial new findings about a "dark state" of DNA in which it is susceptible to damage by ultraviolet radiation could shed light on the origins of life itself, chemists at Oregon State University claim. The theory initially considered scientific heresy could overturn much of our understanding of biochemistry by showing that the four bases of which DNA is comprised, adenine, thymine, guanine and cytosine, are not so stable as scientists originally thought. Indeed, OSU's Wei Kong has shown that although the vibrating "dark state" of the DNA bases exists only fleetingly it leaves the bases open to serious damage and so seemingly could have precluded the emergence of a stable genetic environment except for one vital factor - water. The findings Kong suggests show water to have a stabilizing effect that was absolutely essential in allowing "primordial" DNA bases to remain stable, resist mutation, and ultimately allow for the evolution of life.





Materials engineers at Nanosonic of Blacksburg, Virginia, are spinning novel, electrically conductive textiles in a modified washing machine. The research is a bid to incorporate the company's Metal Rubber as an integral component and so develop e-textiles based on gold and silver to make fairytale weaver Rumpelstiltskin green with envy. "We can spin gold and silver into flexible fabrics and they are electrically conductive and nearly transparent," explains company president Rick Claus. The new nanotextiles could be used for a number of applications, perhaps as shields against disruptive radio frequency radiation. "A cell phone can be wrapped in it and the incoming and outgoing signals are killed," Claus says. The materials might also be made into thicker but lightweight conductive fabrics for electric power workers that would protect them from any hazardous electric power line radiation to which they were exposed.