Strong, crystalline fibers mimic natural spider silk

Spider silk is one of the strongest materials on Earth, thanks primarily to the highly crystalline structure that spiders spin with their specialized silk glands. For decades, researchers have been trying to create synthetic spider silk using industrial processes, but one major challenge has been making fibers as packed with crystals as their natural counterparts. By designing a protein that forms crystalline structures when spun using an industrial process, a group of synthetic biologists have now made a synthetic fiber that’s even stronger than some natural spider silks (ACS Nano 2021, DOI: 10.1021/acsnano.1c02944). Spider silk gets its strength largely from abundant β-nanocrystals. Knowing that amyloid proteins tend to form β-sheets, researchers led by Fuzhong Zhang at Washington University in St. Louis engineered Escherichia coli that fuse amyloid peptides with spidroin, the main protein in spider silk. The researchers wet spun this hybrid protein into a fiber that’s stronger than some spider silks. “The biggest surprise to us was when we found this protein was easy to purify and easy to process,” Zhang says. He proposes that the method could even be a renewable replacement for making synthetic fibers like nylon. “Hopefully one day, most of the fabrics that people are wearing will be made from renewable processes,” Zhang says.