Thursday, February 14, 2008

fun with molecules

Today's Kewl thing of the day is hydrogen bonds.  Some guys have a theory as to why wimpy hydrogen bonds can make spider silk proteins stronger than steel.
In a paper published in the Feb. 13 online issue of Nano Letters, Buehler and graduate student Sinan Keten describe how they used atomistic modeling to demonstrate that the clusters of three or four hydrogen bonds that bind together stacks of short beta strands in a structural protein rupture simultaneously rather than sequentially when placed under mechanical stress. This allows the protein to withstand more force than if its beta strands had only one or two bonds. Oddly enough, the small clusters also withstand more energy than longer beta strands with many hydrogen bonds.

“Using only one or two hydrogen bonds in building a protein provides no or very little mechanical resistance, because the bonds are very weak and break almost without provocation,” said Buehler, the Esther and Harold E. Edgerton Assistant Professor in the Department of Civil and Environmental Engineering. “But using three or four bonds leads to a resistance that actually exceeds that of many metals. Using more than four bonds leads to a much-reduced resistance. The strength is maximized at three or four bonds.”
Put this together with the nanowire maker from yesterday, you've got some serious potential for a brand new generation of super strong materials.

How about ligament replacements for guys with knee ligament tears that are stronger than the original and less prone to immune response problems?  That'd be outstanding.  These days ACL/PCL tears are replaced with a piece of your own ligament stolen from some other place on your body.  I always thought that solution sucked.

The Ligamentous Phantom

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