Originally Published MDDI June 2003
|Spider silk exhibits two distinct, alternating regions. One is soft and elastic while the other has small, hard crystallites. Part of the MIT research is focused on developing processing methods that will provide these properties.|
Spider silk has a number of qualities that make it a unique form of polymer. It offers a combination of lightness, strength, and toughness that high-performance synthetic fibers cannot equal. Scientists have now spent decades trying to find a way to mimic these qualities of natural spider silk for a range of applications, such as artificial tendons. For example, in January 2002, Nexia Biotechnologies (Vaudreuil-Dorion, QC, Canada) announced that a milestone had been reached in its technology for spinning fibers from recombinant spider silk extracted from the milk of transgenic goats.
Now, scientists at the Massachusetts Institute of Technology (MIT; Cambridge, MA) are addressing the challenge from two directions. Says Paula T. Hammond, PhD, associate professor in MIT's department of chemical engineering, “The main goal is to be able to reproduce the enormous energy absorption and strength-bearing properties of spider silk.” She explains that the research group wants to be able to obtain “a material in large quantities and cheaply. . .without DNA techniques, which are expensive.”
The group includes graduate students LaShanda James-Korley and Greg Pollock and is part of a collaborative effort between Hammond and Gareth McKinley, PhD, associate professor of mechanical engineering in MIT's department of mechanical engineering. Pollock explains that the team's focus is on alternatives to spider silk for creating high-strength fibers. Pollock notes that spiders are difficult to domesticate for production purposes. “They're territorial and cannibalistic,” he says.
As a polymer, spider silk has two distinct alternating regions—one is soft and elastic while the other forms small, hard crystallites. This unusual structure is viewed as largely responsible for the material's properties. The MIT researchers are trying to make a series of different synthetic polymers. They then intend to study how changes in the chemical structures of the polymers affect the physical properties. They explain that this phase of their project is being done in parallel with research focusing on processing techniques that will maintain the unusual properties of the materials produced.
Pollock explains that the work being done at Nexia does not solve the problem entirely. “It's some fabulous work,” he says, but “no one has really figured out what nature's done and why it works.” He adds that the goal is to better understand “the structure-property relationships by creating our own material with a mechanism for toughness and seeing [if] the structural units produce toughness the same way the amino acids in spider silk produce toughness.”
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