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Scientists have long been intrigued by the remarkable properties of spider silk, which is stronger than steel, yet incredibly lightweight and flexible. Now, Fuzhong Zhang, professor of energy, environmental and chemical engineering at Washington University, St. Louis, has made a significant breakthrough in the fabrication of synthetic spider silk, potentially offering a new era of sustainable clothing production.
Since engineering recombinant spider silk in 2018 using bacteria, Zhang has been working to increase yield of silk threads produced from microbes while maintaining its desirable properties of enhanced strength and toughness. Higher yields will be critical if synthetic silk is to be used in everyday applications, so this could provide more eco-friendly alternatives to traditional textiles.
Using an engineered mussel foot protein, Zhang has created new spider silk fusion proteins, called bi-terminal Mfp fused silks (btMSilks). Mussels secrete proteins on their feet to stick to things. Zhang and his collaborators have engineered bacteria to produce them and engineer them as adhesives for biomedical applications. Mussel foot proteins are also cohesive, which enables them to stick to each other well, too. By placing mussel foot protein fragments at the ends of his synthetic silk protein sequences, Zhang created a less repetitive, lightweight material that’s at least twice as strong as recombinant spider silk.
“The beauty of synthetic biology is that we have lots of space to explore,” Zhang said. “We can cut and paste sequences from various natural proteins and test these designs in the lab for new properties and functions. This makes synthetic biology materials much more versatile than traditional petroleum-based materials.”
In coming work, Zhang and his team will expand the tunable properties of their synthetic silk fibers to meet the exact needs of each specialized market. “Because our synthetic silk is made from cheap feedstock using engineered bacteria, it presents a renewable and biodegradable replacement for petroleum-derived fiber materials like nylon and polyester,” Zhang said.
This research was supported by the U.S. Dept. of Agriculture and the National Science Foundation. The findings were recently published in Nature Communications.