Genetically Modified Silkworms Can Produce Spider Silk That’s Stronger Than Kevlar

The sturdy, biodegradable fibers could one day be used for surgical sutures or armored vests

Spools of spider silk
Gene-editing silkworms produced this spider silk. Junpeng Mi

Spider silk is an unparalleled material: It’s strong and tough, yet also lightweight and flexible. But getting spiders to mass-produce their silk for commercial purposes has proven nearly impossible. For one, they’re cannibals, so raising them in large numbers is a challenge. Spiders also typically only produce enough silk to make their webs.

But scientists haven’t given up on spider silk entirely. Instead, they’ve focused their energy on making artificial spider silk and genetically modifying other organisms to be able to produce the stretchy stuff.

Now, researchers have successfully gene-edited silkworms to produce spider silk that’s six times stronger than Kevlar, the material used in bulletproof vests.

This heavy-duty fiber could one day be used for surgical sutures, wound dressings, armored vests and structural materials for vehicles. It could also one day serve as a greener alternative to synthetic materials, like polyester and nylon, which shed harmful microplastics and are derived from fossil fuels.

“Spider silk stands as a strategic resource in urgent need of exploration,” says study co-author Junpeng Mi, a biologist at Donghua University, in a statement.

Researchers recently described their process and findings in the journal Matter.

Silkworms have long been cultivated for their silk, but the fibers they naturally produce break easily. Scientists got around this by taking steps that included using the gene-editing tool CRISPR-Cas9 to insert spider silk protein genes into silkworms. They also made localized changes to the inserted genes to ensure they cooperated with the worms’ existing silk-producing mechanisms.

The tweaks allowed the genetically modified silkworms to produce full-strength, flexible, biodegradable spider silk fibers. The fibers aren’t quite as stretchy or as strong as silk produced naturally by spiders, but they have “better mechanical properties than anybody else has been able to show,” says Randy Lewis, a molecular biologist at Utah State University who was not involved with the study, to ScienceNews’ Saima S. Iqbal.

Like spiders, the silkworms also coated the fibers with a protective layer that can help them withstand sunlight and humidity. As such, the gene-edited silkworms are an “all-in-one station for spider silk fiber production,” Mi tells NewScientist’s Alice Klein.

The researchers are optimistic that large-scale commercialization could be in the silkworms’ future. But before they can scale up to commercial production, the researchers will need to overcome a few hurdles.

First, they need to determine if the inserted spider silk protein genes get passed down to new generations of silkworms via normal breeding, reports Science’s Katherine Bourzac. They will also need to cross-breed the genetically modified silkworms with commercial silkworms that are already used for silk cultivation. Finally, they’ll need to deal with the intellectual property issues that could arise from distributing gene-edited silkworm eggs to farmers.

In addition, they’ll need to deal with the same challenges current silkworm farmers face. Silkworms are susceptible to infection, and they are known to produce fibers with varying mechanical properties, per ScienceNews.

Moving forward, the researchers also hope to tinker with the process a bit more to see if silkworms can produce even stronger, stretchier spider silks.

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