Scientists in China have synthesized spider silk from genetically modified silkworms, producing fibers six times tougher than Kevlar:
Previously developed processes for spinning artificial spider silk have struggled to apply a surface layer of glycoproteins and lipids to the silk to help it withstand humidity and exposure to sunlight — an anti-aging “skin layer” that spiders apply to their webs.
Genetically modified silkworms offer a solution to this problem, says Mi, since silkworms coat their own fibers with a similar protective layer.
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To spin spider silk from silkworms, Mi and his team introduced spider silk protein genes into the DNA of silkworms so that it would be expressed in their glands using a combination of CRISPR-Cas9 gene editing technology and hundreds of thousands of microinjections into fertilized silkworm eggs.
The microinjections posed “one of the most significant challenges” in the study, said Mi, but when he saw the silkworms’ eyes glowing red under the fluorescence microscope — a sign that the gene editing had been successful — he was overjoyed.
The researchers also needed to perform “localization” modifications on the transgenic spider silk proteins so that they would interact properly with proteins in the silkworm glands, ensuring that the fiber would be spun properly. To guide the modifications, the team developed a “minimal basic structure model” of silkworm silk.
“This concept of ‘localization,’ introduced in this thesis, along with the proposed minimal structural model, represents a significant departure from previous research,” says Mi. “We are confident that large-scale commercialization is on the horizon.”