Spiders give some folks the heebie-jeebies, but web-weaving arachnids produce a unique, versatile material that could be the textile of the future.

They spin a silk that’s as strong as steel, incredibly elastic and environmentally friendly.

From medical materials to car parts, the applications for this wondrous material are endless—but producing it in bulk is tricky.

Attempts to farm spiders for their threads have generally gone poorly largely because spiders are fiercely territorial cannibals and lab-grown spider-silk replicas have struggled to match the strength of the real thing—until now.

A team of Japanese scientists has finally untangled the mystery of how spiders spin super-strong threads and can re-create the process with synthetic materials.

With biotech companies keen to mass-produce these synthetic silks as sustainable alternatives to nylon, polyester and other petroleum-derived fabrics, the future of spider textiles seems silky smooth.

WEBS OF WONDER

Spider silk has a unique combination of tensile strength and elasticity that has intrigued scientists for centuries.

Arachnids produce several types of silk for different purposes, including building webs, wrapping prey, protecting their offspring and escaping from predators.

These silks are all distinct from one another and are produced in different glands.

Of these varieties, “draglines,” which spiders use to dangle from and move about, are particularly enticing to researchers.

Draglines are believed to have a tensile strength exceeding 1 gigapascal, which is comparable to steel, and more than twice as strong as silkworm silk.

In addition, the draglines are tough, capable of absorbing twice as much energy before breaking as nylon, which is among the strongest man-made materials.

The idea of putting this marvelous material to practical use is not new.

One researcher made a pair of gloves and other items using spider silk in early 18th-century France, and fabrics made of naturally golden spider silk were among the exhibits in the 1900 Paris Exposition.

Although attempts to farm spiders like silkworms proved impractical, the mass production of synthetic spider silk became a holy grail for material scientists.

Researchers identified the main proteins that make up spider silk fibers and developed genetically engineered microorganisms that can produce these proteins.

Artificial spider silk made in this way has a significantly lower carbon footprint than polyester, nylon, or plant- or animal-based fabrics.

However, while the lab-grown proteins mimicked the structure and properties of natural spider silk, the synthetic threads were noticeably less tough, since scientists did not fully understand how the spinning process transforms the natural silk proteins inside a spider’s body from a liquid state into solid fiber.

THE BIG BREAKTHROUGH

A Japanese research team led by Keiji Numata, a professor of polymer chemistry at Kyoto University, has finally cracked that code.

In 2024, Numata’s team became the first in the world to successfully artificially replicate the intricate transformation process—unraveling how proteins deposited in spiders’ major ampullate glands solidify into fiber when released from their spinning ducts.

The discovery showed that phosphate ions play a crucial role in gathering protein molecules to form small granules in the upper regions of the spider’s major ampullate gland.

As these proteins move down the spinning duct, they are joined by hydrogen ions, which cause them to solidify and transform into a mesh-like structure that makes spider silk so strong and flexible.

“We now understand at the molecular level how spider silk, a natural polymeric material, is made inside the spider’s body, so we can apply that knowledge to designing synthetic materials,” Numata said.

Synthetic spider silk has a wide range of potential applications, including medical uses and as a shock absorption material in vehicles and structural materials for buildings.

However, the material has a drawback that needs to be addressed before it can reach its full potential: a vulnerability to water and humidity.

Spider silk threads extend when they absorb water and shrink when they dry.

Numata aims to overcome this obstacle by altering the amino acid sequences of spider silk proteins, to make the synthetic threads more water resistant and better suited for practical use.

“One day, we might come up with artificial spider silk that could outperform natural spider silk due to modified amino acid sequences,” he said.

FERMENTED FABRICS

Spiber Inc., a Yamagata-based biotech startup founded in 2007, has also had to overcome “the water problem,” to mass-produce artificial spider silk for practical use.

Spiber developed a method to produce spider-silk-like proteins called Qmonos, by designing new amino acid sequences of spider silk protein, and introducing the altered DNA to microorganisms that can produce these proteins.

However, Qmonos, named after a Japanese word for spider webs, “kumonosu,” remained sensitive to humidity because the company’s alterations to the DNA sequences were minimal.

Spiber improvised by altering the proteins’ amino acid sequences to improve the material’s response to water.

Spiber mass-produces the synthetic silk by feeding plant-based sugar to its bioengineered microorganisms, which create the silk proteins via a fermentation process.

Material produced with this method, called Brewed Protein, has been used to make clothing, automobile seats and other products.

Another advantage of synthetic spider silk is its low-carbon footprint compared to conventional synethetic fibers, which are commonly used to make clothing, bags and shoes.

The U.N. Conference on Trade and Development called the apparel and fashion industry the second largest polluter after the petroleum industry.

The fashion industry uses an estimated 93 billion cubic meters of water annually, enough to fulfill the needs of 5 million people.

Two to 8 percent of the world’s emissions of greenhouse gases are estimated to come from the manufacturing of garments, according to the U.N. Environment Program. 

In addition, synthetic fibers made from plastics are not biodegradable, persisting in the environment for decades. Washing clothes made of plastic materials also releases miniscule fibers called microplastics that pollute the sea.

While natural fibers such as cotton are biodegradable, producing them requires vast amounts of water and pesticides. Some cotton production is from regions with limited water resources, where the effects of climate change can be devastating.

Brewed Protein on the other hand, is made through a precision fermentation process and has less environmental impact throughout its lifecycle, according to Spiber.

The company estimates that producing Brewed Protein fiber emits 79 percent less greenhouse gases and uses 97 percent less water than producing cashmere fiber.

However, synthetic spider silk is costly to produce, at least for now.

Spiber is trying to overcome that hurdle by devising a method to produce more synthetic proteins with reduced amounts of sugar.

“We are working to provide a high-quality and low-cost material by enhancing the protein-producing microorganisms’ productivity,” a Spiber official said.