Spider silk is spun by genetically modified silkworms for the first time

Scientists in China have developed a method to produce spider silk from genetically modified silkworms, providing a strong and sustainable alternative to synthetic fibers with applications in various industries.

The researchers created spider silk from genetically modified silkworms, producing a fiber six times stronger than the Kevlar fiber used in bulletproof vests. The study was published September 20 in the journal Theme, was the first to successfully produce full-length spider silk proteins using silkworms. The results demonstrate a technology that can be used to manufacture an environmentally friendly alternative to synthetic commercial fibers such as nylon.

“Silkworm silk is currently the only animal silk fiber that is widely commercialized, using well-established breeding techniques,” Mei said. “Therefore, the use of genetically modified silkworms to produce spider silk fibers enables low-cost and large-scale commercialization.”

Picture of forced roller silk. Credit: Junpeng Mei

Sustainability of spider silk

Scientists are looking at spider silk as an attractive, sustainable alternative to synthetic fibres, which can release harmful microplastics into the environment and are often produced from fossil fuels that generate greenhouse gas emissions. But turning to nature for alternatives is not without challenges. Processes previously developed for spinning synthetic spider silk have struggled to apply a surface layer of glycoproteins and lipids to the silk to help it withstand moisture and exposure to sunlight — an anti-aging “skin layer” that spiders apply to their webs.

Mee says genetically modified silkworms offer a solution to this problem, as the silkworms cover their fibers with a similar protective layer.

“Spider silk represents a strategic resource that is in urgent need of exploration,” said Junping Mei, a doctoral candidate at Donghua University’s School of Bioscience and Medical Engineering and first author of the study. “The exceptionally high mechanical performance of the fibers produced in this study holds great promise in this field. This type of fiber can be used as surgical sutures to meet a global demand exceeding 300 million surgical procedures annually.

Spider silk fibers could also be used to make more comfortable clothing and innovative types of bulletproof vests, Mei says, and may have applications in smart materials, the military, aerospace technology, and biomedical engineering.

Silk fiber produced by genetically modified silkworms. Credit: Junpeng Mei

Synthesis process and challenges

To spin spider silk from silkworms, Mei and his team inserted spider silk protein genes into the cell DNA From silkworms to be expressed in their glands using a combination of CRISPR-Cas9 gene editing technology and hundreds of thousands of microinjections into fertilized silkworm eggs. Mei said ICSI posed “one of the most important challenges” in the study, but when he saw the silkworms’ eyes glow red under a fluorescence microscope — a sign of successful gene editing — he was thrilled.

“I danced and practically ran to Professor Meng Qing’s office to share this result,” Mei said. “I remember that night clearly, the excitement keeping me awake.”

The researchers also needed to make “localization” modifications to the genetically engineered spider silk proteins so that they interacted correctly with proteins in the silkworm glands, ensuring the fibers were spun correctly. To guide modifications, the team developed a “miniature basic structural model” of silkworm silk.

“The concept of ‘localization’ introduced in this thesis, together with the simple structural model proposed, represents a significant departure from previous research,” says Mee. “We are confident that large-scale commercialization is on the horizon.”

future prospects

In the future, Mei plans to use insights into the durability and strength of spider silk fibers developed in the current study to develop genetically modified silkworms that produce spider silk fibers from natural and engineered materials. Amino acids.

“The introduction of more than a hundred engineered amino acids holds limitless potential for engineered spider silk fibers,” says Mei.

Reference: “High-strength and ultra-tough whole spider silk fiber spun from genetically modified silkworm” by Junpeng Mi, Yizhong Zhou, Sanyuan Ma, Xingping Zhou, Shouying Xu, Yuchen Yang, Yuan Sun, Qingyou Xia, Hongnian Zhu, Suyang Wang, Luoyang Tian and Cheng Meng, September 20, 2023, Theme.
doi: 10.1016/j.matt.2023.08.013

This work was supported by the National Natural Science Foundation of China, Key Projects of the Shanghai Municipal Science and Technology Commission, International Cooperation Projects of the Shanghai Municipal Science and Technology Commission, and the Fundamental Research Funds for the Central Universities.