The natural world is full of useful materials and organisms that inspire these designs. Scientists have always been interested in the amazing properties of spider silk, and have now successfully produced it from another species, the humble silkworm.
Previously, synthetic materials have often had to compromise between high tensile strength and toughness – tensile strength being the amount of stress a material can withstand while being stretched before breaking, and toughness indicating how much shock would be required to crack a material. For example, commonly made fibres like nylon have a higher toughness, while Kevlar possesses superior tensile strength.
Spider silk, full of exciting properties including exceptional strength and a lightweight feel, is both stronger than nylon and tougher than Kevlar, but extremely difficult to mass produce. This is primarily because spiders don’t work well with others and have a tendency to eat each other, making large-scale production by rearing spiders quite difficult.
Scientists also don’t fully understand how the silk is spun within the spiders, and thus have struggled to replicate the exact conditions needed. Silkworms, on the other hand, are regularly used in commercial operations producing their own silk and have remarkably similar glands to the spider silk gland, requiring similar conditions. Given these similarities, they have now been genetically altered to produce spider silk instead.
The team used CRISPR-Cas9-mediated gene editing to create whole polyamide spider silk fibers from these transgenic silkworms. Essentially, they put the spider silk-making instructions within the silkworm’s silk-making gland, to extraordinary success. This was achieved via a series of microinjections into fertilized silkworm eggs.
The fibers that were created by the silkworms have an impressive strength and a toughness that is six times stronger than the Kevlar used in bulletproof vests. They have also overcome some of the problems faced when creating spider silk artificially, allowing it to retain the mechanical properties of the silk over time. This represents the first time full-length spider silk proteins have been created using silkworms.
The team suggests this provides a sustainable alternative to making synthetic commercial fibers and could have a whole range of applications, from defense to biomedical engineering.
“Silkworm silk is presently the only animal silk fiber commercialized on a large scale, with well-established rearing techniques,” said Junpeng Mi, a PhD candidate at the College of Biological Science and Medical Engineering at Donghua University and the first author of the study, in a statement. “Consequently, employing genetically modified silkworms to produce spider silk fiber enables low-cost, large-scale commercialization.”
The study is published in Matter.
Biomimetics is a field of science that's also seen living animals inspiring new robot designs, and among the experts is Dr Mostafa Hassanalian, an associate professor at New Mexico Tech who will be telling us all about the pill bug robots that could one day explore lava tubes on other planets at CURIOUS Live. Join us for a free festival of science on Saturday 21 October, 2023, where we'll be tackling curious questions around Life, Death, and Creation. Y'know, the small stuff.