As the nights draw in and the days get colder, our thoughts naturally turn towards the otherworldly.
Even in the eminently scientific realm of biomaterials, we get unexpected glimpses of the uncanny if we peer closely.
From the gruesome hagfish to the blackest of blacks, this feature looks at the world’s spookiest biomaterials, paying homage to the wondrousness of nature on which biomanufacturing depends.
These bio-horror tales are best read next to the fire, mug in hand, and one ear out for any bumps in the night.
Hagfish slime
Slithery, slimy, and ancient: hagfish are one of the most reviled creatures of the deep. These predator-scavengers live in every ocean except the polar ones and have been around for at least 300 million years. Yet their bottom-dwelling habits mean that most people, at least in the West, have not encountered them.
Spineless and jawless, their snake-like bodies are eerie enough. But their secret weapon is slime – their primary defence mechanism.
When Hagfish feel threatened, they release a milky mucus-and-thread mixture from their bodies. Once the concoction mixes with seawater, the ingredients form the incredibly strong, stretchy, and transparent substance – a substance so thick that it clogs the gills of any fish that tries to eat them, suffocating the predator-turned-victim.
The power of this saline goo came to public notoriety in 2017 thanks to a road accident in Oregon, US. A truck containing 3,400 kg of Hagfish overturned while transporting them to Korean culinary markets. The road was instantly slathered in a stretchy coating of Hagfish slime, resembling layers and layers of thickened clingfilm.
Yet Hagfish slime is not simply a grotesque curiosity. Material scientists have been fascinated by its properties for years because it holds immense industrial applications. Specifically, scientists are interested in the thin protein fibres that make up the slime. These become silk-like when dried and could form the basis of sustainable textiles, especially for high-performance applications.
Despite their industrial potential, we still lack a precise working model of how the slime is structured and why it behaves the way it does. This has made it difficult for scientists to artificially re-create the slime and its critical constituents inside labs.
The reason we still lack a full explanation for the slime’s physical properties is that Hagfish slime is a highly complex substance. 90 milligrams of the Hagfish’s mucus-thread secretion can create more than a litre of slime once combined with seawater. The mysterious thing here is that the final slime substance is mostly composed of “just” seawater – in fact, Hagfish slime is 1000 times more dilute than typical mammal mucus. Yet with a smattering of mucus and silk-like proteins, it can do things that ordinary mucus could not.
Hagfish slime is an example of just why biology is vital in the search for new, more sustainable industrial materials. Though its constituents appear relatively simple and few in number, its properties are more than the sum of its parts. In other words, natural evolution has created something more elegantly complex than humans could have thought up on their own. Science continues to unpick the sticky intricacies of this future bio-textile.
Spider’s web fibres
Spiders are the stuff of occult lore: silent weavers of the darkest crevices, spinning esoteric patterns in silvery thread. Now, their webs have become the stuff of modern biomanufacturing and the way they get made is nothing short of magic too.
Spider silk has become a raw material in cutting-edge low-carbon clothing textiles. It is easy to see why, given that it strikes that elusive balance between strength and flexibility. Made of protein, it is also biodegradable, unlike the fossil plastic fibres that make up most of the world’s textiles.
Yet industry producers do not simply harvest its threads from unsuspecting arachnids. Japanese startup Spiber, a heavyweight in spider silk textiles, carefully grows synthetic spider silk inside custom-engineered, patented microbes. From there, the silk protein is extracted, purified and processed into fibres.
Spiber’s so-called ‘Brewed Protein’ is chemically similar to the constituents of natural spider’s silk in crucial ways. However, it is modified to better fit its end applications. For example, natural spider silk shrinks in water – not ideal for clothing.
To fix this, the company identified the amino acids associated with shrinkage and altered it to make a material more stable in water. Similar methods can be used to adjust the sensory properties of Brewed Protein. The end result may resemble cashmere, lamb’s wool, or silk.
Evolution has been creating highly-adapted materials in a similar way over millions of years. Spiber is recreating some of this magic in the lab, using the tools of modern genetics to conjure up dreamily soft yet rigorously functional fibres without any exact analogue in nature.
The natural mysteries of the spider’s web have not all been unravelled. There are probably thousands of natural proteins out there with special properties that could serve as the basis of other new materials. Spiber released its Spider Silkome Database in 2022 that lists all protein gene sequences that make up spider silk, enabling other developers to potentially construct and explore whole new webs of functional materials.
Blackest black
What’s the blackest black you’ve ever seen? Think the inkiest of nights, the dimmest of forests, the abyssal depths of a laptop screen that has run out of charge.
Chances are, you still haven’t come close to seeing true black: nature contains few surfaces that absorb almost all light that hits it.
For most of modern history, the darkest of industrial dyes have come from fossil fuels. Coal is one of the few natural materials to give a solid and immersive black, the kind that envelops you like a winter’s evening.
From the 17th century to the 20th, a whole dye industry grew up around the Bideford coal deposits found in North Devon, UK. The coal seams here yield a particularly rich dark mineral pigment. ‘Bideford Black’, as it is known, supplied the paints, paper, cement, textiles and cosmetics industries. Today, this naturally occurring black still sold to artists in the form of ink.
Outshining (out-darkening, even) Bideford Black are the ‘super-black’ synthetic coatings of modern times. The company Surrey NanoSystem sells one known as ‘Vantablack’, which for a long time claimed the world record for the darkest man-made substance. MIT researchers in 2019 came up with an even darker material they say is 10 times blacker than anything that came before.
Such intense blacks are only useful in high-spec applications, for example in aerospace and defence. Today, most of the black dye in consumer goods and textiles is the humbler Carbon Black, created by burning heavy oil or natural gas to create a sooty pigment.
Carbon Black is one of the most produced chemicals on the planet, favoured for its relatively cheap cost and its resistance to fading under UV exposure. Its presence inside so many commercial goods only adds to the environmental problems posed by plastics and other non-renewables.
Yet deep, durable blacks need not come from the murky depths of the oil industry. Biobased versions of black dye are now on the market, offering companies a way of honing their product aesthetic without relying on fossil chemicals.
US startup Nature Coatings has produced a wood waste-based black pigment meant to replace almost any instance of petroleum-based carbon black. Recently, it entered the cosmetics market where it is vying to replace Carbon Black and Black 2 – common in mascaras, eyeliners, and nail polish – with its own sustainable pigments.
Algae is another rapidly growing source of biobased black dye, underlining the prodigious versatility of this wonder-feedstock. Denver Colorado’s Living Ink is one of the companies at the forefront of algal black dyes, working specifically with algal waste to achieve an even more sustainable manufacutring process. It has partnered with companies that want to remove petrochemicals from their product range, including Stella McCartney. The British designer featured Living Ink’s Algae Black in their Spring 2024 Collection.
The xenobots are coming
With the rise of commercial AI, all eyes are now on the autonomous robots industry, which could be the next tech sector to blow up.
Amidst all the excitement, we forget that biotech may yet have a leading role in future robotics. The most sophisticated robots we may yet create might not be from plastic or metal but rather the stuff of life: cells.
In around 2020, scientists at the the University of Vermont, Tufts University, and the Wyss Institute for Biologically Inspired Engineering at Harvard University created autonomous organisms almost from scratch, assembling ordinary, unmodified stem cells from the African clawed frog Xenopus laevis on a petri dish.
The inert cells soon began to self-assemble, transforming into motile, life-like bots that could move around and perform very specific tasks. The researchers’ aim had been to build tiny, organic robots to perform intricate tasks at the microscopic scale – collecting microplastics from the ocean, for example, or perform medical work inside the human body.
Half-organism, half-computer, this kind of entity is known as a xenobot: synthetic lifeforms built on biological hardware to perform pre-set activities.
In 2021, the researchers observed something surprising about their cellular creations: they were managing to self-replicate spontaneously. The researchers had initially nudged their xenobots to perform the simple task of collecting together tiny unattached cells and organising them into piles. Yet they found that these simple piles were eventually morphing into brand new, fully-functional xenobot replicas.
Xenobots move and replicate somewhat like a living creature but there are key differences between them and natural organisms – for example, they lack a brain or a digestive system. Arranged by humans but made entirely from natural cells, xenobots inhabit that dusky twilight zone between machine and organism, nature and artefact, life and death.