Learning From Spiders: How Spider Silk Inspires Sustainable Clothing

Spider Silk: An Important Opportunity for the Clothing Industry

Every year, the textile industry uses huge amounts of plastic materials to make clothes. Around five million tons of these plastics end up in the environment and do not break down. These plastics enter the soil and the water, ultimately reaching our food sources—plants and animals alike. Recent studies have shown that a human can unknowingly consume up to 5 g of plastic every week. This corresponds to the weight of a credit card [1]. About one third of this plastic (around 2 g) comes directly from the textile industry [2]. Some tiny plastic particles can remain in our bodies for a long time, and they may carry chemicals that can change how our bodies work.

This huge environmental problem is caused by two main factors. First, people tend to buy too many clothes, even when they do not need them, and frequently from non-sustainable sources. Second, the textile industry currently relies mostly on petroleum-based fibers—in other words, plastics—to produce fabrics and clothes. The first issue can be solved by changing our lifestyles, while the second requires a much deeper transformation of the textile industry. To avoid plastic accumulation in the environment, we must find sustainable substitute materials to produce fabrics [1].

To do this, we can draw inspiration from nature and learn to produce fibers from one of the most fascinating animals on Earth: spiders. Spiders spin silks, which are made mostly of proteins—a bit like the ones found in meat, eggs, or milk. Spiders produce many kinds of proteins, which they store like treasures inside their bodies in specialized organs called silk glands. Each spider has several types of glands (up to seven), and each one produces a different silk protein [3].

With these proteins, spiders spin fibers that they use for a wide variety of purposes. Some spiders use silk fibers to build clever traps that can catch or lift prey, even when the prey is thousands of times larger than the spider itself [4]. Spiders can even “fly” using these fibers: they release a thread of silk that catches the wind, which lets them glide for hundreds of kilometers.

Spider silks have incredible properties. They are as strong as steel, yet far more stretchable, seven times lighter, and most importantly, biodegradable. What makes these fibers even more interesting from a textile point of view is that spiders produce them at room temperature, using mainly water—factors that make them incredibly sustainable. Spider silks represent a unique opportunity for the textile industry to develop sustainable fibers for clothes (Figure 1).

Figure 1 - Spider silk is an extraordinary fiber: strong, lightweight, stretchable, and biodegradable. Even better, spiders produce it under environmentally friendly conditions, using mainly water and working at room temperature. In recent decades, scientists have learned how to produce spider silk artificially and in large quantities, by inserting spider genes into bacteria. Our group has even managed to make it magnetic by mixing it with tiny magnetic nanoparticles.

You might be wondering why people do not simply breed spiders and collect silk from them. In fact, people have tried and failed. Spiders are cannibalistic, which means they sometimes eat other spiders, and they also produce very small amounts of silk. For example, there is only one cape in the world made entirely of spider silk. To collect enough silk to make it, 75 people worked for 8 years, gathering silk from 1.2 million spiders! Clearly, this is not efficient. Therefore, if we want to produce spider silk for the textile industry, we must do it artificially.

Making Artificial Spider Silk

Producing spider silk artificially is very difficult, and it has taken scientists a long time to get it right. Since spider silk is made of proteins, the first step in producing artificial spider silk is to make artificial spider silk proteins. How can we do so? The answer lies in genetics. Every organism has DNA, which contains the genes that tell cells how to make proteins. By introducing spider silk genes into other organisms, we can make those organisms produce spider silk proteins for us.

All organisms are constantly making proteins—in fact, you are producing proteins right now as you read this! The challenge is not just getting these organisms to make proteins, but getting them to make the exact proteins we want, and then isolating those proteins so we can use them. Modifying complex organisms to produce spider silk proteins can be very challenging. In the early 2000s (before many of you were even born!), a group of scientists in the United States tried to modify a goat so that it would produce spider silk proteins in its milk. While the results were interesting, they did not produce enough protein to make even something as simple as a T-shirt.

A better solution is to use bacteria, tiny organisms that live just about everywhere, including in and on our bodies. Specifically, scientists use bacteria called Escherichia coli, which are much easier to modify than goats because they are made of only one simple cell. The first successful attempt to produce spider silk proteins using E. coli happened in 1997 [5]. Almost 25 years later, this method is now greatly improved, and artificial spider silk proteins can be produced in very large quantities, enough for the textile industry [6].

Once we have these proteins, we can spin them into fibers using a method called biomimetic spinning [7]. This means we mimic how spiders spin their silk. The proteins are mixed with water and pushed through a tiny tube into a special acid bath (a bit like a salad dressing). When they touch the bath, the proteins unfold (you can imagine them like curly spaghetti noodles that straighten out), stick to each other, and squeeze out the water, forming a solid thread.

We have tested these fibers, and the results are impressive [8]! In terms of how much they can be stretched before breaking, our fibers are twice as tough as Kevlar, one of the strongest man-made fibers used in things like pilots’ helmets. And the best part? We produce artificial silk fibers at room temperature, while making Kevlar usually requires temperatures of 100°C.

Despite their amazing properties, our artificial spider silk fibers are not perfect. For example, they do not naturally have magnetic or electric properties, which are important for “smart” textiles—clothes that can sense and respond to signals from our bodies. Magnetic fibers are called “smart” because they can move or change when a magnet is nearby. This makes it possible to control them without even touching them. Thus, developing artificial fibers that are mechanically strong, sustainable, and magnetic would be a game-changer for technologies like soft robotics and wearable electronics.

Making Artificial Spider Silk Magnetic

The first idea to make spider silk magnetic was to coat the fibers with magnetic materials. For example, there are several metallic alloys, made from cobalt (a metal used mostly for making batteries) and iron, that could be used. Our research group tried this approach with both natural and artificial spider silk, but the resulting fibers were not strong enough, so we had to change our strategy [9].

Here is where the beauty of artificial spider silk production comes in. What if we could mix tiny magnetic particles directly with the proteins before spinning the fibers? When we say tiny, we mean really tiny: each particle is about 40 nanometers across, which means they are roughly 2,500 times thinner than a human hair! Because they are small, sphere-like, and magnetic, scientists call them magnetic nanoparticles.

We tried to mix magnetic nanoparticles directly into our silk proteins but the mixture was too thick and it was difficult to make fibers. The few fibers we managed to make were weak and fragile, which is no good for making textiles. These nanoparticles do not mix easily with water—they tend to clump together. Normally, scientists solve this problem using harsh chemicals, like strong acids. But we wanted to keep our process green, water-based, and safe. So, a collaborator in Spain helped us make nanoparticles that mix with water and are easier to handle at room temperature [10]. To do this, they coated the magnetic nanoparticles with a substance commonly used in medicine to treat heavy metal poisoning.

This worked surprisingly well! With this coating, we could mix the silk proteins and nanoparticles in water and spin fibers efficiently. The resulting fibers have excellent mechanical and magnetic properties, making them perfect candidates for smart textiles that move, sense their environment, or adapt to different human needs [11]. We are now working hard to improve these fibers even further, and we hope that soon we will be able to create the first products out of them.

What Can the Textile Industry Learn From Spiders?

The textile industry is currently not sustainable because it releases millions of tons of plastic into the environment each year. To reduce this pollution, we need sustainable alternatives to plastic-based fibers. Spiders offer us a brilliant inspiration: they produce many kinds of silks that are strong, light, stretchable, biodegradable, and made at room temperature using only water.

By inserting spider silk genes into bacteria, we can produce large amounts of silk proteins, which can be spun into fibers. To make these fibers suitable for smart textiles, we added magnetic nanoparticles, which allowed the production of strong, magnetic, sustainable artificial spider silk fibers, paving the way for sustainable smart textiles that will help make clothes that can sense movement, monitor our health, or power tiny devices.

Glossary

Textile: ↑ Any material that can be woven, knitted, or used to make clothes, like cotton or wool. Your T-shirt and jeans are made from textiles.

Sustainable: ↑ It means using materials and resources in a way that protects nature, creates less waste, and makes sure people in the future can still use and enjoy them.

Proteins: ↑ Molecules that living things use to build and repair their bodies. They are like the “bricks” of life, found in muscles, skin, hair, and many other parts of plants and animals.

Biodegradable: ↑ Something that can naturally break down into simple, harmless parts with the help of tiny organisms like bacteria, returning safely to the environment.

Biomimetic: ↑ Something humans make by copying how nature works.

Alloys: ↑ Mixtures of two or more metals. For example, steel is an alloy made from iron and carbon, and it is stronger than either one alone.

Nanoparticles: ↑ Extremely tiny particles—so small that you cannot see them even with a normal microscope—that scientists use to give materials new or special properties.

Conflict of Interest

The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Acknowledgments

This work was supported by FORMAS (2023-00871) to B.S, Olle Engkvist stiftelse (233-0334), Knut and Alice Wallenberg Foundation (2023.0331, WASP-DDLS2 2:035 and Wallenberg Launch Pad) European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreements No 1010693 ArtSilkTex and No 815357 ARTSILK), FORMAS (2023-01313), and the Swedish Research Council (2024-02919). 7). G.G. was supported by the project “EPASS” under the HORIZON TMA MSCA Postdoctoral Fellowships - European Fellowships (project number 101103616).

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↑Greco, G., Schmuck, B., Del Bianco, L., Spizzo, F., Fambri, L., Pugno, N. M., et al. 2024. High-performance magnetic artificial silk fibers produced by a scalable and eco-friendly production method. Adv. Compos. Hybrid Mater. 7:163. doi: 10.1007/s42114-024-00962-y

[1] ↑ Pletz, M. 2022. Ingested microplastics: do humans eat one credit card per week? J. Hazard. Mater. Lett. 3:100071. doi: 10.1016/j.hazl.2022.100071

[2] ↑ Manshoven, S., Smeets, A., Arnold, M., and Mortensen, L. F. 2021. Plastic in textiles: potentials for circularity and reduced environmental and climate impacts. Eur. Top. Cent. Waste Mater. 53:1–53. doi: 10.5281/zenodo.4475340

[3] ↑ Sonavane, S., Hassan, S., Chatterjee, U., Soler, L., Holm, L., Mollbrink, A., et al. 2024. Origin, structure, and composition of the spider major ampullate silk fiber revealed by genomics, proteomics, and single-cell and spatial transcriptomics. Sci. Adv. 10:eadn0597. doi: 10.1126/sciadv.adn0597

[4] ↑ Greco, G., and Pugno, N. M. 2021. How spiders hunt heavy prey: the tangle web as a pulley and spider’s lifting mechanics observed and quantified in the laboratory. J. R. Soc. Interface. 18:20200907. doi: 10.1098/rsif.2020.0907

[5] ↑ Fahnestock, S. R., and Irwin, S. L. 1997. Synthetic spider dragline silk proteins and their production in Escherichia coli. Appl. Microbiol. Biotechnol. 47, 23–32. doi: 10.1007/s002530050883

[6] ↑ Schmuck, B., Greco, G., Barth, A., Pugno, N. M., Johansson, J., and Rising, A. 2021. High-yield production of a super-soluble miniature spidroin for biomimetic high-performance materials. Mater. Today. 50:16–23. doi: 10.1016/j.mattod.2021.07.020

[7] ↑ Andersson, M., Jia, Q., Abella, A., Lee, X. Y., Landreh, M., Purhonen, P., et al. 2017. Biomimetic spinning of artificial spider silk from a chimeric minispidroin. Nat. Chem. Biol. 13:262–4. doi: 10.1038/nchembio.2269

[8] ↑ Schmuck, B., Greco, G., Bäcklund, F. G., Pugno, N. M., Johansson, J., and Rising, A. 2022. Impact of physio-chemical spinning conditions on the mechanical properties of biomimetic spider silk fibers. Commun. Mater. 3:83. doi: 10.1038/s43246-022-00307-6

[9] ↑ Spizzo, F., Greco, G., Del Bianco, L., Coïsson, M., and Pugno, N. M. 2022. Magnetostrictive and electroconductive stress-sensitive functional spider silk. Adv. Funct. Mater. 32:1–14. doi: 10.1002/adfm.202207382

[10] ↑ Salas, G., Casado, C., Teran, F. J., Miranda, R., Serna, C. J., Morales, M. P., et al. 2012. Controlled synthesis of uniform magnetite nanocrystals with high-quality properties for biomedical applications. J. Mater. Chem. 22:21065–75. doi: 10.1039/c2jm34402e

[11] ↑ Greco, G., Schmuck, B., Del Bianco, L., Spizzo, F., Fambri, L., Pugno, N. M., et al. 2024. High-performance magnetic artificial silk fibers produced by a scalable and eco-friendly production method. Adv. Compos. Hybrid Mater. 7:163. doi: 10.1007/s42114-024-00962-y