Silkworms “spit out” spider silk, which is 6 times tougher than bulletproof vest fibers

Meng Qing, a professor at Donghua University’s School of Biological and Medical Engineering, and Xia Qingyou, a professor at Southwest University’s Institute of Advanced Interdisciplinary Studies, worked to make the genetically modified silkworm “spit out” spider silk, which is 6 times tougher than the Keiraville fiber used in bulletproof vests. The study was published Sept. 20 in Substance. This is the first time that full-length spider silk proteins have been successfully produced from silkworms, and the research demonstrates new technologies that can be used to create environmentally friendly alternatives to commercial synthetic fibers.

Scientists see spider silk as a promising and sustainable alternative to synthetic fibers. Synthetic fibers release harmful microplastics into the environment, often produced from fossil fuels that produce greenhouse gas emissions. The previously developed artificial spider silk process requires coating the silk with a layer of glycoproteins and lipids, similar to an anti-aging “skin layer” applied by spiders on the web to help it resist moisture and light.

Genetically modified silkworms offer a solution to this problem, and silkworms also wrap a similar protective layer around their own fibers. Silk is currently the only large-scale commercial animal silk fiber, and has a complete feeding technology, which makes the use of genetically modified silkworms to produce spider silk fiber achieve low-cost, large-scale commercialization.

In order to make the silkworm “spit out” the spider silk, the researchers introduced the spider silk protein gene into the silkworm’s DNA, using the gene-editing technology CRISPR-Cas9 and hundreds of thousands of microinjections into the fertilized egg to express the spider silk protein in the silkworm’s glands. In this study, microinjection was one of the most significant challenges.

Mi Junpeng, the first author of the paper and a doctoral student at Donghua University’s School of Biological Sciences and Medical Engineering, still remembers his ecstasy when he saw the silkworm’s eyes, which are a sign of successful gene editing, glowing red under a fluorescence microscope. “I went to Professor Meng Qing’s office to share the results. That night, I couldn’t sleep with excitement. Mi Junpeng recalled.

The research also requires localization modifications of the transgenic spider silk protein so that it can interact properly with the proteins in the silkworm gland to ensure that the fibers can be spun normally. To this end, the team developed a minimal basic structural model of silk. “The positioning concepts we introduced in our study and proposed minimal structure models represent significant differences from previous studies. We believe large-scale commercialization is coming. Mi Junpeng said.

He said that the spider silk fibers produced in the new study have extremely high mechanical properties and have important application prospects. For example, they can be used as surgical sutures to meet the needs of more than 300 million surgeries worldwide each year. Spider silk fibers can also be used to make more comfortable clothing and new bulletproof vests, and are found in smart materials, military, aerospace technology and biomedical engineering.

As a next step, the researchers plan to use their understanding of the toughness and strength of spider silk fibers in the current study to develop transgenic silkworms that can produce natural and engineered amino acid spider silk fibers. “The introduction of more than 100 engineering amino acids can provide unlimited potential for engineered spider silk fibers.” Mi Junpeng said.

Spider silk protein fibers spit out by transgenic silkworms. Image from: Mi Junpeng

Spider silk protein fibers spit out by transgenic silkworms. Image from: Mi Junpeng

The silk glands of the silkworm. Image from: Mi Junpeng

(Source: China Science News Feng Lifei)

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