CAMBRIDGE, Mass. Researchers in Civil and Environmental Engineering at MIT reveal that the strength of a biological material like spider silk lies in the specific geometric configuration of structural proteins, which have small clusters of weak hydrogen bonds that work cooperatively to resist force and dissipate energy.
This structure makes the lightweight natural material as strong as steel, even though the glue of hydrogen bonds that hold spider silk together at the molecular level is 100 to 1,000 times weaker than the powerful glue of steels metallic bonds or even Kevlars covalent bonds.
Based on theoretical modeling and large-scale atomistic simulations implemented on supercomputers, this new understanding of exactly how a proteins configuration enhances a materials strength could help engineers create new materials that mimic spider silks lightweight robustness. It could also impact research on muscle tissue and amyloid fibers found in brain tissue.
Our hope is that by understanding the mechanics of materials at the atomistic level, we will be able to one day create a guiding principle that will direct the synthesis of new materials, said Professor Markus Buehler, lead researcher on the work.
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 brea
|Contact: Denise Brehm|
Massachusetts Institute of Technology, Department of Civil and Environmental Engineering