Ancient Golden Silk Used by Emperors Brought Back to Life

A luxurious fiber once reserved exclusively for emperors in ancient times has been brought back to life through the scientific ingenuity of Korean researchers. A team led by Professor Dong Soo Hwang (Division of Environmental Science and Engineering / Division of interdisciplinary bioscience & bioengineering, POSTECH) and Professor Jimin Choi (Environmental Research Institute) has successfully recreated a golden fiber, akin to that of 2,000 years ago, using the pen shell (Atrina pectinata) cultivated in Korean coastal waters. This breakthrough not only recreates the legendary sea silk but also reveals the scientific basis behind its unchanging golden color. The study was recently published in the prestigious journal Advanced Materials.

Sea silk—often referred to as the “golden fiber of the sea”—was one of the most prized materials in the ancient Roman period, used exclusively by figures of high authority such as emperors and popes. This precious fiber is made from the byssus threads secreted by Pinna nobilis, a large clam native to the Mediterranean, which uses the threads to anchor itself to rocks. Valued for its iridescent, unfading golden color, light weight, and exceptional durability, sea silk earned its reputation as the “legendary silk.” A notable example is the Holy Face of Manoppello, a relic preserved for centuries in Italy, which is believed to be made from sea silk.

However, due to recent marine pollution and ecological decline, Pinna nobilis is now an endangered species. The European Union has banned its harvesting entirely, making sea silk an artifact of the past—produced only in minuscule quantities by a handful of artisans.

The POSTECH research team turned their attention to the pen shell Atrina pectinata, a species cultivated in Korean coastal waters for food. Like Pinna nobilis, this clam secretes byssus threads to anchor itself, and the researchers found that these threads are physically and chemically similar to those of Pinna nobilis. Building on this insight, they succeeded in processing pen shell byssus to recreate sea silk.

However, their achievement goes beyond mere replication of its appearance. The team also revealed the scientific secret behind sea silk’s distinctive golden hue and its resistance to fading over time.

The golden color of sea silk is not derived from dyes, but from structural coloration—a phenomenon caused by the way light reflects off nanostructures. Specifically, the researchers identified that the iridescence arises from a spherical protein structure called “photonin,” which forms layered arrangements that interact with light to produce the characteristic shine. Similar to the color seen in soap bubbles or butterfly wings, this structure-based coloration is highly stable and does not fade easily over time.

Moreover, the study revealed that the more orderly the protein arrangement, the more vivid the structural color becomes. Unlike traditional dyeing, this color is not applied but instead generated by the alignment of proteins within the fiber, contributing to the material’s remarkable lightfastness over millennia.

Another significant aspect of this research is the upcycling of pen shell byssus, previously discarded as waste, into a high-value sustainable textile. This not only helps reduce marine waste but also demonstrates the potential of eco-friendly materials that carry cultural and historical significance.

Professor Dong Soo Hwang noted, “Structurally colored textiles are inherently resistant to fading. Our technology enables long-lasting color without the use of dyes or metals, opening new possibilities for sustainable fashion and advanced materials.”

Reference: Choi J, Im J, Kim Y, et al. Structurally colored sustainable sea silk from atrina pectinata. Adv Mater. 2025:2502820. doi: 10.1002/adma.202502820

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