Silkworms that eat nanometre-sized particles called quantum dots produce glow-in-the-dark silk.
Researchers have previously used gene editing to make fluorescent silkworms, but these methods can be costly and introduce random genetic mutations that are harmful to the worms.
Instead, Huan-Ming Xiong at Fudan University in Shanghai, China, and his colleagues extracted carbon quantum dots, nanometre-sized semiconductors that emit specific wavelengths of light, from mulberry leaves and fed them to the silkworms.
Xiong and his team tested dozens of different carbon dots on the silkworms to find candidates with good fluorescence, biocompatibility and safety for the animals. “It is very lucky for us that we can make red-emissive carbon dots from mulberry leaves, because silkworms like to eat them,” says Xiong.
Once the silkworms had eaten the quantum dots, the researchers observed that the worms, as well as their silk, eggs, cocoons and moths, gave off a strong red glow when irradiated with visible light. The second generation of silkworms, which hatched from eggs normally, no longer glowed.
Apart from its aesthetic qualities, the researchers hope the fluorescent silk might be used in biomedical research. For example, it could be used to encapsulate drugs and see where they are released as the silk breaks down, without needing any special equipment.
“Fluorescent silkworms are an excellent model for bioimaging research,” says Xiong. “Now, the laser confocal microscope and animal imaging system are not needed, because we can see the fluorescence from the body directly by the naked eye.”
The mulberry leaf method also appears to be more sustainable compared with other techniques, says Antonios Kelarakis at the University of Central Lancashire in Preston, UK. “It is a readily scalable method that does not require any change of practice or financial investment from the producer.”
But further studies will be needed to see whether the red carbon dots have any long-term toxicity for the silkworms or environment, he says.
Reference:
Jun Liu et. al, Mulberry Leaves Derived Red Emissive Carbon Dots for Feeding Silkworms to Produce Brightly Fluorescent Silk, Advanced Materials DOI: 10.1002/adma.202200152