If your greatest problem with your silk clothes is that they don't look impressive enough under black light, you're in luck. Researchers in Japan have genetically engineered silkworms that spin silk that glows under fluorescent light.
Top photo by 白石崖.
The researchers, led by Tetsuya Iizuka and Toshiki Tamura of the National Institute of Agrobiological Sciences in Ibaraki, Japan, transplanted genes that produce fluorescent proteins into the silkworms' DNA. The silkworm genome contains a site that codes for the silk fiber protein fibroin, and the researchers transplanted genes into that site from Fungia concinna coral—to create silk that glows orange under fluorescent light—Discoma coral—for silk that grows red—or jellyfish—for silk that glows green. Unmodified silkworms can produce colored silk if fed certain dyes, but these modified silkworms produce their fluorescent colors on a normal diet.
Image from Advanced Functional Materials.
The glowing silk has to be processed in a different way from normal silk. Typically, silkworm cocoons are heated to 100 degrees C, but the heat kills the fluorescent proteins. Instead, the fluorescent cocoons need to be softened in a weak alkaline solution and heated to a lower temperature in a vacuum.
The colors are less visible under non-fluorescent light, but remain vibrant for more than two years under fluorescent light. More than 20,000 genetically engineered silkworms have been pumping out this glowing silk, which is already appearing in clothes. Tamura hopes to find medical uses for the material as well.
The findings appear in Advanced Functional Materials.