Researchers at Tsinghua University in China have shown that feeding silkworms mulberry leaves sprayed with an aqueous solution containing a 0.2% (by weight) graphene or carbon nanotubes can result in reinforced silk that could be used in applications like durable protective fabrics, biodegradable medical implants, and wearable electronics.
This carbon-enhanced silk is said to be twice as tough as regular silks, and can withstand at least 50% higher stress before breaking. The team heated the silk fibers at 1,050 °C to carbonize the silk protein and then studied their conductivity and structure. The modified silks conduct electricity, unlike regular silk. Raman spectroscopy and electron microscopy imaging showed that the carbon-enhanced silk fibers had a more ordered crystal structure due to the incorporated nanomaterials.
The researchers explain that treating already spun silk would require dissolving the nanomaterials in toxic chemical solvents and applying those to the silk, so the feeding method is simpler and more environmentally friendly. As for remaining questions, like how the silkworms incorporate the nanomaterials in their silk and what percentage of the nanomaterials eaten by the worms makes it into the silk, further examinations will be in order.