Spider silk has attracted the interest and attention of scientists all over the world for its excellent performance. In recent years, the United States, Switzerland, Canada, Japan, Germany, Denmark and other countries have conducted in-depth research on spider silk, solved the mystery of spider silk by using gene and protein determination technology, and made a breakthrough in artificial production of spider silk. With the rapid development of genetic engineering technology and biomaterial technology, in the near future, spider silk will be developed and utilized on a large scale like silk and widely used in science and technology, national defense, industry and other fields. 1 properties of spider silk The physical density of spider silk is 1.34 g/cm, which is similar to that of silk and wool. Spider silk is smooth and shiny, with strong ultraviolet resistance and high and low temperature resistance. Thermal analysis shows that spider silk shows thermal stability below 200℃ and turns yellow above 300℃. However, silk showed thermal stability below 1 10℃ and began to turn yellow at 140℃. Spider silk has special solubility, its orange color deepens when it meets alkali and fades when it meets acid. Insoluble in dilute acid and alkali, only soluble in concentrated sulfuric acid, potassium bromide, formic acid, etc. And it is resistant to most hydrolytic proteases. Spider silk has considerable expansion in water and obvious contraction in the longitudinal direction. When heated, it is slightly soluble in ethanol. Spider silk is almost entirely made of protein, so it is biodegradable and recyclable. Spider silk is one of the best structural materials produced in nature, and its excellent comprehensive properties are incomparable to all kinds of natural fibers and synthetic fibers. So far, humans have not been able to produce compounds with super strength and elasticity like it. Its specific modulus is better than steel, and its toughness is better than Kevlar fiber. As an excellent energy-absorbing fiber, it is considered as an ideal material for making parachutes and bulletproof vests. Spider silk, especially its traction silk, has outstanding advantages over silk and general synthetic fibers in mechanical properties. In terms of strength, it is similar to Kevlar fiber for making body armor, but its breaking work is 1.5 times that of Kevlar fiber, its fastness is 1 times that of steel, and its initial modulus is much larger than that of nylon, reaching the high strength and high modulus level of Kevlar fiber. The elongation at break of spider silk is 36% ~ 50%, while Keerwal fiber is only 2% ~ 59/6, so it has the performance of absorbing huge energy. In viscoelasticity, spider silk is higher than nylon and Kevlar fiber. The weight of spider silk is 25 9/6 lighter than that of chemical synthetic silk, but its elasticity can be extended to 10 times. Another important feature of spider silk is its resistance to low temperature. It is reported that spider silk is still elastic at 40℃, and will only harden at lower temperature. The advantages of this fiber are especially obvious when it needs to be used at low temperature. Therefore, spider silk has the characteristics of high strength, good elasticity, large initial modulus and high fracture work, and is a very excellent material. Artificial spider silk has excellent properties, so it is a long-term dream of materials scientists to obtain this protein or similar protein and then spin it to prepare artificial spider silk. 2. 1 microbial plant spinning This method is to transfer the spider silk gene into bacteria, yeast or plants, obtain spider silk protein through bacterial fermentation, and then extrude this protein from micropores to obtain extremely fine silk. Once the breeding factory of this bacteria is established successfully, it will bring a revolution to the textile and garment industry. However, due to various reasons, this method has not been successful so far, mainly because the prepared protein has little water solubility and can only be dissolved in formic acid, and hexafluoroisopropanol needs to be added as a diluent, so water cannot be used as a solvent for further processing. 2.2 Milk Spider Silk Canada's Nexia Biotechnology Company (NXB) tried another method. They injected spider silk gene into goat egg cells to prepare recombinant spider silk protein, and used this protein-water system to complete the environmental protection spinning process. Because it is more similar to the composition and spinning process of natural spider silk protein in essence, it successfully imitated spiders and produced the world's first "artificial spider silk" in June 2002. Nexia cooperated with the scientists of the US Army Soldier Biochemical Command (SBCCOM) to genetically modify the cells of two kinds of mammals, using the golden spider and the spider as the gene sources. Spider silk gene was injected into goat egg cells, and the structure and performance of protein in this transgenic goat milk were completely simulated by spider silk protein. The highest purity of recombinant spider silk protein can reach 70% ~ 90%, the mass concentration of spinning aqueous solution is 2.89/6 ~ 28% (mass/volume), and the diameter of spun fiber is 8 ~ 40 gm. Spinning adopts a special micro spinning machine, which is a prototype produced by Harvard Equipment Company. The volume of spinning solution solvent is 0.5 ml, and the inner diameter is only 5 mm The spinning head was replaced by PEEK HPLC tube (Sigma-—Aldrich product), with a length of 6 cm and an inner diameter of 0. 125mm. The spinning solution is driven by a micro reciprocating pump. The micro spinning machine can work with at least 25μl spinning solution, the flow rate of the pump is 2 ~ 65438 00 μ l/min, and the coagulation bath consists of 70% ~ 80% methanol aqueous solution. The diameter of the first generation of biological steel is 1 ~ 2 orders of magnitude larger than that of natural spider silk. It is reported that electrospun spider silk can reach the fineness of real spider silk. However, natural spider silk has a skin-core structure, which seems difficult to imitate at present. The biggest difference between biological steel production and spider spinning is that the latter is liquid crystal spinning. In spider silk gland, protein with different lengths can be distinguished, with molecular weights of 120, 150, 190, 250 ku and 750 ku, respectively, and the concentration is as high as 30% ~ 50%, which is acidic and becomes a liquid crystal solution. Liquid crystal is characterized by its low viscosity, which can be deformed into filaments with little force, which is the key to the exquisiteness of spider silk. It seems that human beings still need to make great efforts to truly imitate spiders and realize large-scale green high-performance fiber production. The mammalian cells used by scientists of Nexia Company at the beginning of their research were taken from cows, but now they find it more beneficial to use goats for transgenic treatment. Goats have 70 thousand genes. They genetically engineered goats to carry spider silk genes. June 5438+October 2002 10, Nexia officially announced the birth of two such "biological steel goats", which were named webster and Peter respectively. The patented technology of Nexia is based on the anatomical similarity between the silk glands of spider silk and the cells of goat mammary gland, so the columnar epithelial cells in two very different animals can produce a large number of water-soluble complex protein macromolecules. In principle, it can be achieved with cows. Nexia technology, but goats grow faster and easier. By June 2002, Nexia had cooperated with the US military to cultivate 150 transgenic goats, which were raised in a former air base in P P 1attsbtlrgh, new york, and the development was accelerating. Using the environmentally friendly processing of milk and goat's milk, high-performance fibers can be produced, which was considered to be just an illusion 10 years ago. Nowadays, the appearance of artificial spider silk has become a great miracle of contemporary material science. In the United States, China and other countries, cows and hamsters have also been studied in this field. 2.3 Silkworms Spit Spider Silk This method uses the method of "electroporation" in transgenic technology to inject the spider dragline gene into silkworm eggs which are only half the size of sesame, so that cultured silkworms secrete spider silk containing dragline protein. In recent years, the scientific and technical personnel of Shanghai Institute of Biochemistry have solved a series of technical problems such as gene introduction, active gene identification and subculture breeding of transgenic silkworms by this method. This research has been listed as the key project of the national "863" plan and is currently under way. 3 Application of Spider Silk Spider silk has important applications in many fields because of its special and excellent performance. 3. 1 military spider silk is strong, elastic, soft and light, especially has the ability to absorb huge energy, which is very suitable for making bulletproof vests. The performance of spider silk bulletproof vest is better than that of aramid fiber bulletproof vest. It can also be used to make armor for tanks and planes, as well as "body armor" for military buildings. Spider silk can also be used to weave parachute silk, which is light in weight, anti-winding, powerful in deployment, good in wind resistance and durable. 3.2 Aerospace can be used for high-strength materials such as structural materials, composite materials and aerospace garments. 3.3 Medical care is widely used in medical and health fields. Because spider silk is a natural product, composed of protein, and has good compatibility with human body, it can be used as a high-performance biomaterial to make wound sealing materials and physiological tissue engineering materials, such as artificial joints, artificial tendons, ligaments, artificial limbs, tissue repair, biodegradable ultra-fine wound sutures in neurosurgery and ophthalmology. , with good toughness and biodegradability. 3.4 Buildings can be used as structural materials and composite materials for bridges, high-rise buildings and civil buildings. Conclusion For more than 200 years, people have been interested in the application of spider silk. However, in recent ten years, scientists have been able to decipher the mystery of spider silk by using new technologies such as gene and protein determination. The appearance of artificial spider silk is the result of human learning from nature, and it is also a great miracle of contemporary material science. With the rapid development of modern science and technology, the research on artificial manufacturing and industrial application of spider silk has been deepened and expanded, and its industrial production technology has become more and more mature, which makes the history that spider silk can not be produced in large quantities like silk come to an end. Spider silk will be widely used in textile and garment industry, military, medical care, aerospace, construction and automobile industry, and become a new generation of advanced biomaterials.
I looked for it, hehe, I didn't mention the molecular structure.