Shimmering like spun gold, sea silk cloth is so lustrous that some imagine it impressed the Greek legends of Jason’s quest for the Golden Fleece. For hundreds of years, artisans within the Mediterranean have handed down the artwork of spinning the silk, which comes from the beardlike tufts of the enormous clam Pinna nobilis. However the clam’s endangered species standing has made it arduous to maintain the custom alive.
Now, scientists have re-created the legendary cloth utilizing discarded components of Atrina pectinata, a associated clam species farmed extensively in South Korea for meals. They’ve additionally recognized the exact molecular construction and formation behind sea silk’s eternal golden hue, the researchers report July 29 in Superior Supplies.
“A lot of this species’ fiber is thrown out as waste when it might be used as a brand new supply of sea silk, says Dong Soo Hwang from the Pohang College of Science and Know-how in Korea. “If we accumulate it as a substitute, we might open a brand new department of sustainable luxurious.”
Sea silk has lengthy been constructed from the enormous clam P. nobilis, which is native to the Mediterranean and might develop as much as 4 ft lengthy. The earliest identified point out of the silk dates again to the second century, when Tertullian, a Carthaginian lawyer turned Christian author, described it in De Pallio: “Nor was it sufficient to comb and sow the supplies for a tunic; it was vital additionally to fish for one’s gown; for fleeces are obtained from the ocean, the place shells of extraordinary measurement are furnished with tufts of mossy hair.”
The silk comes from the clam’s byssus threads, wispy however thick threads that anchor it to seaweed, sand, and stone. Historically, the threads are fastidiously harvested and rinsed in seawater to take away seaweed and sand, then washed with gentle water to attract out salt and left to air dry. Subsequent, the fibers are meticulously combed to boost their shiny sheen and spun on picket spindles. After being soaked in lemon juice for twenty-four to 36 hours, a remaining spherical of washing, drying and brushing concludes the method.
The ensuing sea silk is “tremendous as youngsters’s hair,” says Felicitas Maeder, a researcher on the Pure Historical past Museum of Basel in Switzerland. “A glove would really feel like nothing in any respect,” says examine coauthor Jimin Choi, a organic engineer additionally on the Pohang College of Science and Know-how.
However since 1992, the European Union has banned the harvesting of P. nobilis, and following a large die-off, it was formally categorized as endangered in 2019. Then, Hwang and his group had found that the threads of A. pectinata, a intently associated clam, shared hanging bodily and chemical similarities to the endangered species — and importantly, A. pectinata is already extensively obtainable in Korea. “Everytime you go to a seafood restaurant or Costco [in Korea], a lot of the [scallops] you’re consuming are Atrina,” Hwang says.
Importantly, the byssus of A. pectinata is often discarded as waste. To Choi and Hwang, this was the right alternative for upcycling. After they replicated the normal sea silk manufacturing course of, they efficiently created golden threads from A. pectinata that had been nearly indistinguishable from these of the endangered P. nobilis.
This got here as no shock to Maeder, who has spent a long time collaborating with Mediterranean sea silk artisans to piece collectively the material’s historical past. One weaver, Arianna Pintus from Carbonia, Italy, had already independently found A. pectinata threads may work simply as effectively, Maeder says.
The researchers additionally uncovered what provides sea silk its shimmering golden hue. In contrast to most animal-based fibers like wool or silk, that are constructed from lengthy, fibrous proteins, the group discovered that sea silk is primarily composed of spherical proteins known as photonins. These globular proteins assemble into nanofibrils that twist collectively in helical bundles.
Like butterfly wings or cleaning soap bubbles, the shimmer arises from how gentle displays off nanostructures. In untreated byssus, iron ions masks the impact. However a soak in citric acid — the lemon bathtub — removes the iron, clearing the way in which for the golden hue to emerge.
As a result of sea silk’s golden luster comes from pigment reasonably than construction, the colour “doesn’t fade for greater than 1,000 years,” Choi says.
Globular proteins are usually unstable, Hwang says. However in sea silk, photonins are bolstered by a mesh of sugars and matrix proteins that present further power and sturdiness. The extra ordered the protein construction is inside the fibers, the extra sensible the structural shade turns into, the researchers be aware.
These findings couldn’t solely assist revive sea silk manufacturing, but additionally engineer unhazardous golden pigments to be used in textiles or cosmetics, Hwang says. “I’m hoping possibly somebody in Louis Vuitton may even see our work and phone us about sending a pattern.”
