Domestic researchers have revived the top-quality fibers that were once enjoyed only by ancient emperors through science and technology.
A research team led by Professor Hwang Dong-soo from the Department of Environmental Engineering and the Department of Systems Biotechnology at Pohang University of Science and Technology POSTECH, Professor Lee Gi-ra from the Department of Chemical Engineering, and Professor Choi Ji-min from the Environmental Research Institute has recreated the golden fiber from 2,000 years ago using cultivated clams, or 'gaper clams,' from domestic coasts instead of the endangered Mediterranean clam, which is prohibited from collection. They also uncovered the secret of why the color does not fade. This research was published in the international journal on materials, 'Advanced Materials,' in April.
Known as 'sea silk,' this silk is a luxurious fabric that could only be used by a select few powerful individuals, such as emperors or popes, from the Roman era. This silk is made from the 'byssus,' a thread produced by the giant clam 'Pinna nobilis' that lives in the Mediterranean, which it emits in order to anchor itself to rocks. Due to its non-fading color over time, lightweight nature, and exceptional durability, it was considered a precious and special material, often referred to as 'the legendary silk.'
However, due to recent ocean pollution, it has become nearly extinct, and the European Union (EU) has completely banned the collection of Pinna nobilis. As a result, sea silk has remained as a 'museum artifact,' made in extremely limited quantities by a small number of artisans.
The research team focused on 'gaper clams,' which are cultivated for consumption on domestic coasts, in order to recreate sea silk. Similar to Pinna nobilis, gaper clams also use byssus to anchor themselves. The researchers noted that the physical and chemical properties of the byssus from both clams are very similar, leading them to process the byssus from the gaper clams like traditional sea silk.
Based on this, they uncovered the secret of why this fiber exhibits a golden color and does not fade over thousands of years. The golden hue of sea silk is not created using dyes; instead, it is the result of a phenomenon called 'structural coloration,' in which spherical proteins known as 'photonin' stack up in layers to uniquely reflect light. Structural coloration, like that found in soap bubbles or butterfly wings, is a phenomenon where the material's structure itself produces color, making it resistant to change over time.
The researchers also revealed that the more orderly the protein arrangement, the clearer the structural coloration becomes. Thanks to this structure, sea silk has excellent light stability, retaining its color for thousands of years.
Another significance of this research is that it has transformed the byproducts of gaper clam byssus, which had been discarded, into high-value fibers. This not only helps solve the marine waste problem but also demonstrates the potential as a new fiber material that is environmentally friendly while carrying cultural heritage.
Professor Hwang Dong-soo said, 'Fibers based on structural coloration have properties that do not fade,' adding, 'This technology, which realizes long-lasting color without dyes or metals, will open a new path for the eco-friendly fashion industry and advanced material development.'
References
Advanced Materials (2025), DOI: https://doi.org/10.1002/adma.202502820