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WHY THE WORLD NEEDS MORE SPIDER SILK AND CAN'T GET IT
Story by Natasha Rego • 2d ago
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Spider silk is like something out of a comic book.

It is superstrong. Flexible. Elastic. When compared in terms of strands of the same diameter, it is stronger than steel, tougher than Kevlar (the synthetic polymer used in bulletproof vests).

The webs of orb weaver spiders (the group of species that weave the biggest and strongest known webs) can measure up to 1.5 metres in diameter, and can trap small birds mid-flight.

If scientists could figure out how to produce enough spider silk, the possibilities would be immense. It could be used in medicines and weaponry, armoured clothing and aerospace technology.

The problem is, spiders are incredibly difficult to domesticate.

“They don’t function well in captivity. If you keep a group of them together, one of them will eat the others,” says Aarathi Prasad, an Honorary Research Fellow at University College London’s Department of Genetics, Evolution and Environment, and author of Silk: A History in Three Metamorphoses (2023). “The reason it has been so challenging to use spider silk over the centuries is because you can’t get enough of it.”

Scientists are now aiming to get around this, by experimenting with ways to make spider silk — without the spider.

In a paper published in the journal Matter in September, scientists from China’s Donghua University described how they had successfully used genetically modified silkworms to produce spider-silk fibres.

The gene-editing tool CRISPR-Cas9 was used to insert genes for spider silk protein into the DNA of the silkworms. The silk produced by these genetically modified worms showed a tensile strength and flexibility close to natural spider silk.


Fibres of spider-like silk produced by silkworms. © Provided by Hindustan Times


This isn’t undilutedly good news, and we’ll get to why in a bit, but the Donghua experiment was a significant improvement over other attempts.

For over a decade, for instance, researchers at Utah State University had experimented with ways to extract spider silk protein from the milk produced by genetically modified goats. They too, introduced genes for spider silk protein into the goat’s DNA. This protein was then extracted from the milk and reverse-engineered into fibre. But the fibre was weak, the experiment has essentially been concluded, and the goats now live on a farm run by the university.

Previous attempts to produce artificial spider silk in a lab, meanwhile, failed to replicate the surface layer of glycoproteins and lipids, which is a protective layer that spiders apply on their webs during secretion, to guard against humidity and sun exposure.

Silkworms are a promising workaround because they have their own specialised gland which secretes a similar protective coating. But, Prasad says, it still can’t be 100% spider-like.

“In the spider’s body, the silk starts as a liquid before becoming a solid thread,” says Prasad.

“The problem with genetically engineering spider silk has been that you are only able to replicate the chemical structure of the material partially. It’s always going to be part spider, part moth. It’s not going to be true spider silk because we don’t yet know exactly how the spider folds the silk during the secretion process, to give it its strength.”

Donghua is hoping to crack that code too.

The university’s research team is working on making the silkworm-generated spider silk stronger and more elastic, by adding additional amino acid chains to its molecular structure.

The good news: What they have so far is certainly scalable. As Donghua biotechnologist Junpeng Mi said in a statement: “Silkworm silk is currently the only animal silk fibre that has a well-established supply chain, complete with advanced rearing and processing techniques.”



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