Shimmering like spun gold, sea silk cloth is so lustrous that some consider 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 large 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 may very well be used as a brand new supply of sea silk, says Dong Soo Hwang from the Pohang College of Science and Expertise in Korea. “If we accumulate it as a substitute, we could open a brand new department of sustainable luxurious.”
Sea silk has lengthy been constructed from the large clam P. nobilis, which is native to the Mediterranean and might develop as much as 4 toes lengthy. The earliest recognized 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 needed additionally to fish for one’s costume; for fleeces are obtained from the ocean, the place shells of extraordinary dimension 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 ultimate spherical of washing, drying and brushing concludes the method.
The ensuing sea silk is “positive 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 research coauthor Jimin Choi, a organic engineer additionally on the Pohang College of Science and Expertise.
However since 1992, the European Union has banned the harvesting of P. nobilis, and following a large die-off, it was formally labeled as endangered in 2019. Then, Hwang and his workforce had found that the threads of A. pectinata, a intently associated clam, shared placing bodily and chemical similarities to the endangered species — and importantly, A. pectinata is already extensively out there in Korea. “Everytime you go to a seafood restaurant or Costco [in Korea], many of the [scallops] you’re consuming are Atrina,” Hwang says.
Importantly, the byssus of A. pectinata is normally discarded as waste. To Choi and Hwang, this was the proper alternative for upcycling. Once they replicated the normal sea silk manufacturing course of, they efficiently created golden threads from A. pectinata that have been nearly indistinguishable from these of the endangered P. nobilis.
This got here as no shock to Maeder, who has spent many years 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 might work simply as properly, Maeder says.
The researchers additionally uncovered what offers sea silk its shimmering golden hue. Not like most animal-based fibers like wool or silk, that are constructed from lengthy, fibrous proteins, the workforce 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 tub — removes the iron, clearing the best way for the golden hue to emerge.
As a result of sea silk’s golden luster comes from pigment fairly 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 strengthened by a mesh of sugars and matrix proteins that present extra energy and sturdiness. The extra ordered the protein construction is inside the fibers, the extra good the structural coloration turns into, the researchers notice.
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.”
