How to Artificially Produce Spider Silk

Spider silk is composed of protein and is biodegradable. Spider silk is more resistant to high temperatures. It exhibits thermal stability below 200°C and starts to turn yellow at above 300°C. Spider silk is resistant to low temperatures, and it still remains at minus 40°C. Elasticity, it hardens only at lower temperatures. The advantages of this fiber are particularly significant in applications requiring low temperatures.

The most attractive part of spider silk is that it has excellent mechanical properties, namely high strength, high elasticity, high flexibility, and high breaking energy. The traction silk of the big belly spider, the frame silk and the outer egg silk have a ratio of breaking strength Silk fibroin is large, the elongation at break is 3~5 times that of silk fibroin, and the specific work at break is much larger than silk fibroin. Although the breaking strength of spider silk is not as good as steel wire and Kevlar used to make body armor, it breaks The elongation is 5-10 times that of steel wire.

Spider silk has broad application prospects. It can be used in textile and clothing; because its protein composition is compatible with the human body, it can be used in medicine and medical treatment; because of its protein fiber‘s high strength and high elasticity, it can be used in military bulletproof vests, parachutes, etc. Therefore, the study of spider silk is of great significance.

Spider silk can be described as the protein material with the most excellent comprehensive properties so far found, so it has become a hotspot for material scientists today. However, people have two biggest difficulties in using spider silk:

1. The spider webs made by spiders provide the raw material of spider silk fiber, and the quantity is limited.
2. Spiders cannot be domesticated. Spiders are carnivorous animals. When several spiders are put together, they often bite each other until each other dies, and use them as food, so it is difficult to raise spiders in large numbers to obtain silk.

So now people are trying to obtain a large amount of spider silk by artificially producing spider silk.

Microbial host method

Using microorganisms to express spider silk protein, the first attempt was to use E. coli and yeast as proxy hosts. LomBardi et al. first expressed the traction silk protein cDNA of the gold-spun spider in E. coli. DuPont of the United States is focusing on researching the technology of using bacteria as proxy hosts.

Animal host method

The method is to use genetic engineering to transfer the protein genes of spider silk to the mammary gland cells of goats or cows. Nexia Bioengineering Company in Montreal, Canada is using genetic modification technology to transfer the spider silk drag silk gene into goat mammary gland cells, thereby producing goat milk containing spider silk protein, and then extracting high-performance protein fibers from the milk. Canada’s Nike Biotechnology Company is conducting research in this area. People take into account the impact of goats on vegetation. In comparison, transgenic experiments on cattle have a brighter future. In fact, the milk production of a cow is much higher than the milk production of a goat.

Plant host method

The method is to insert plant genes into some plants such as potato and tobacco plants so that these plants can produce large amounts of silk protein in their tissues. Udo Conrad of the Catersleben Institute in Germany made artificial variants of the golden-yellow spherical spider silk protein gene and spliced ​​them into the genomes of several plants.They found that more than 2% of the total protein of some plants is composed of silk protein. Researchers estimate that the cost of producing silk in genetically modified plants is only 1/10 of that of bacterial genetic engineering.Unlike bacteria, silk genes in plants are not prone to recombination and loss.

Silkworm host method

The silkworm is used as the expression vector of spider silk gene. By solving a series of key technologies such as transgenic silkworm gene introduction, live gene identification, and passage breeding, some spider drag silks have been produced in the heavy chain of silkworm silk genes. It shows that there have been significant advances in gene directed introduction of the silkworm expression system, laying a foundation for the targeted introduction of spider silk genes into silkworm silk-producing genes.