Hagfish Slime Makes Super-Clothes
A research team has harvested hagfish slime, dissolved it in a liquid and then spun it like silk.
One of the world's creepiest creatures may be the source of new kinds of petroleum-free plastics and super-strong fabrics, according to research by scientists in Canada studying the hagfish, a bottom-dwelling creature that hasn't evolved for 300 million years and produces a sticky slime when threatened. The gooey material is actually a kind of protein that turns into choking strands of tough fibers when released into the water.
A research team at Canada's University of Guelph managed to harvest the slime from the fish, dissolve it in liquid, and then reassemble its structure by spinning it like silk. It's an important first step in being able to process the hagfish slime into a useable material, according to Atsuko Negishi, a research assistant and lead author on the paper in this week's journal Biomacromolecules.
"We're trying to understand how they make these threads and how we can learn from that to make protein-based fibers that have excellent mechanical properties," Negishi said. "The first step is can we harvest the threads. It turns out that is doable."
Negishi has been working with the hagfish for about four years in the laboratory, trying to understand some of the physical and chemical properties of the slime. The fish produces a protein which it releases into the water from glands along the side of its snake-like body. This video by researchers in New Zealand document how the hagfish is able to repel 14 attacks by predators, including several kinds of sharks.
Negishi says the slime can be difficult to handle and there are plenty of reasons why most people, and fishermen, avoid them.
"They're not the prettiest fish, they have big whiskers, they don't have eyes," Negishi said. "They don't smell particularly nice either. They are wet clammy and wiggly. But they you appreciate what they are capable of doing and you respect them."
As for the slime itself, Negishi says it smells like dirty seawater and has the consistency of snot.
"It feels like mucous but a little bit more wet," she said. "If you hold the slime up into the air, the water will drip out of that and what you have leftover is something that is threadlike."
The threads are made of intermediate filament, a protein in the same family as bone and nails. The hagfish threads are 100 times smaller than a human hair and have given the creature an evolutionary advantage as a unique defense mechanism. Negishi works in the laboratory of professor Douglas Fudge, director of the comparative biomaterials laboratory at the University of Guelph. Fudge says he thinks the hagfish slime threads could be woven to produce a material with the strength of nylon or plastic.
"What we'd like to see is synthetic petroleum-based fibers replaced by more sustainable ones," he said.
Fudge says it isn't likely that the slime will be harvested from hagfish in large quantities. A better idea would be to figure out a way to transplant the slime-making genes into bacteria which can be cultured on an industrial scale. Researchers have been doing something similar with the protein that makes spider silk.
The research in Fudge's lab is promising, according to Markus Buehler, professor of civil and environmental engineering at the Massachusetts Institute of Technology, and expert in biological materials.
"It's exciting to see that they have been able to go from studying the natural system to actually take it apart and reassemble them," Buehler said. Still, obstacles remain. "Scaling it up to where you can make engineering products is still a way to go."