Scientists Unveil the Source of Spider Silk’s Strength
Spider silk discoveries uncovered by TU Muenchen (TUM) and the Universitaet Bayreuth (UBT) could lead to stronger plastics.
One of the most memorable passages in Janine Benyus’ book Biomimicry includes the author’s description of spider dragline silk—which is many times stronger than steel by weight, and requires no added heat or pressure to create—and her query about why we cannot make materials in the same fashion. As if fueled by her question, scientists have been racing to determine how spider thread possesses such extreme strength.
Researchers at TU Muenchen (TUM) and the Universitaet Bayreuth (UBT) have come closer to an answer. “The strength of spider dragline silk exceeds that of any material produced in laboratories, by far. All attempts to manufacture threads of similar strength have failed thus far,” says Horst Kessler, a professor at TU Muenchen (TUM).
Kessler and fellow scientists located two regulating elements that determine the strength and tensile properties of threads made from assemblies of individual proteins. The so-called C terminal domain is effectively a gatekeeper, preventing or allowing threads to form within the silk duct. The N terminal domain controls the creation of thread pairs from single strands (monomers), which is critical for tensile strength.
“This is the effect that eventually explains the enormous tensile strength of the spider silk thread,” Kessler says. “Most polymer chemists focus on the length of the thread. So far, no one has come up with the approach of cross-linking the ends of the threads and thereby opening the door to virtually unlimited lengths of polymer chains.”
Future polymer research will likely incorporate this particular technique of cross-linking—called multivalence—which has not yet been developed in synthetic plastics. Once achieved, multivalence could deliver polymers unparalleled in their strength and ductility.