SILK REVOLUTION: UNRAVELING THE SCIENCE AND PRODUCTION OF ADVANCED SPIDER SILK

 

Investing in advanced materials is crucial for enhancing productivity and advancing civilization. Synthetic fibres like nylon and Kevlar have played a significant role in modern civilization but come with environmental concerns. To promote ecological civilization without compromising productivity, there is a need for sustainable alternatives with both high strength and toughness. Current theories suggest that achieving both tensile strength and toughness in engineering materials is challenging, leading to compromises in commercial synthetic fibres.

Biomimetics, drawing inspiration from nature, has been instrumental in developing advanced materials. Natural polyamide fibres like silkworm silk and spider silk have long been sources of inspiration for materials scientists. Spider silk, in particular, has higher tensile strength than nylon and greater toughness than Kevlar, making it an excellent research material. Silk mechanical properties are determined by their quaternary structure, influenced by the primary structure and spinning process. Both silkworm silk and spider silk contain repetitive sequences that form β-sheet crystalline regions, contributing significantly to their mechanical properties.

Silk aligns with sustainability and environmental friendliness, making it a suitable candidate to replace synthetic commercial fibres. However, silkworm silk is limited in mechanical performance, and spider silk production is challenging due to the cannibalistic nature of spiders. Genetic engineering has enabled spider silk protein expression via heterologous hosts, but replicating the natural spinning environment remains a challenge. Additionally, the lack of a protective "cuticle layer" in artificial spider silk reduces its mechanical properties and durability.

To overcome these challenges, researchers have explored using domestic silkworms for spider silk production. By genetically modifying domestic silkworms to produce spider silk, the research team aims to create high-performance spider silk with low-cost, large-scale production.

The researchers propose a theoretical framework that explains the fundamental factors behind fibre toughness and strength, drawing inspiration from the differences between nylon and Kevlar. Using homology modelling, they develop a structural model for silk to understand the mechanical performance differences between silkworm silk and spider silk. This model guides the localization of spider silk proteins within silkworm silk glands, allowing for the production of spider silk with high strength and ultra-toughness. This approach resolves scientific, technical, and engineering challenges, paving the way for the commercialization of high-performance spider silk.

In a groundbreaking development, researchers in China have successfully produced pure spider silk from genetically modified silkworms. The resulting material is six times tougher than Kevlar, a well-known material used in bulletproof vests. While it may not match the strength and stretchiness of natural spider silk, it represents a significant advance over previous attempts to blend spider silk with silkworm silk. Using CRISPR/Cas9, the researchers inserted the complete instructions for making spider silk protein into silkworms, ensuring the protein ended up in their silk-producing glands. This allowed the team to take advantage of the natural machinery of silkworms and produce purer spider silk.

The potential applications of this engineered spider silk are promising. It could be used for robust sutures in medical procedures, stronger armoured vests for police officers, and as an environmentally friendly alternative to synthetic fibres like nylon and polyester. Mass production of spider silk still faces challenges, including ensuring that genetic changes induced in silkworms last over several generations and addressing the insects' susceptibility to infection. The variability in silk properties among different silkworm strains is another obstacle.

Despite these challenges, silkworms remain one of the most attractive candidates for genetic engineering due to their ability to produce silk naturally. The research team hopes to continue developing even stronger and stretchier spider silk by incorporating artificial amino acids into the silk protein. This breakthrough in silk production holds the potential to make a significant impact on various industries and contribute to sustainable and environmentally friendly development.

In conclusion, the production of spider silk from genetically modified silkworms represents a remarkable scientific achievement with far-reaching implications for various applications. By overcoming the challenges associated with mass-producing spider silk, this research opens up new possibilities for the development of sustainable and environmentally friendly materials, fostering the advancement of ecological civilization.

Reference:

Mi J, Zhou Y, Ma S, Zhou X, Xu S, Yang Y, et al. High-strength and ultra-tough whole spider silk fibers spun from transgenic silkworms. Matter. 2023;6(10):3661–83. doi:10.1016/j.matt.2023.08.013