Spider silk creates music, say MIT researchers

Now Buehler — together with David Kaplan of Tufts University and Joyce Wong of Boston University — has synthesized new variants on silk’s natural structure, and found a method for making further improvements in the synthetic material. And an ear for music, it turns out, might be a key to making those structural improvements.

The work stems from a collaboration of civil and environmental engineers, mathematicians, biomedical engineers and musical composers.

“We’re trying to approach making materials in a different way,” Buehler explains, “starting from the building blocks” — in this case, the protein molecules that form the structure of silk. “It’s very hard to do this; proteins are very complex.”

Other groups have tried to construct such protein-based fibers using a trial-and-error approach, Buehler says. But this team has approached the problem systematically, starting with computer modeling of the underlying structures that give the natural silk its unusual combination of strength, flexibility and stretchiness.

Buehler’s previous research has determined that fibers with a particular structure — highly ordered, layered protein structures alternating with densely packed, tangled clumps of proteins (ABABAB) — help to give silk its exceptional properties. For this initial attempt at synthesizing a new material, the team chose to look instead at patterns in which one of the structures occurred in triplets (AAAB and BBBA).

Making such structures is no simple task. Kaplan, a chemical and biomedical engineer, modified silk-producing genes to produce these new sequences of proteins. Then Wong, a bioengineer and materials scientist, created a micro fluidic device that mimicked the spider’s silk-spinning organ, which is called a spinneret.

Even after the detailed computer modeling that went into it, the outcome came as a bit of a surprise, Buehler says. One of the new materials produced very strong protein molecules — but these did not stick together as a thread. The other produced weaker protein molecules that adhered well and formed a good thread. “This taught us that it’s not sufficient to consider the properties of the protein molecules alone,” he says. “Rather, [one must] think about how they can combine to form a well-connected network at a larger scale.”

The team is now producing several more variants of the material to further improve and test its properties. But one wrinkle in their process may provide a significant advantage in figuring out which materials will be useful and which ones won’t — and perhaps even which might be more advantageous for specific uses. That new and highly unusual wrinkle is music.