Study On The Characteristics Of New Silk Containing Spidroin And Its Regeneration Film Materials

Spider silk is a kind of natural protein fiber with superior performance.Spiders cannot be raised on a large scale because of their territorial nature and cannibalism.Therefore,more and more scientists are trying to make artificial spider silk.So far,the most potential method is to transfer the spider silk protein gene into the silkworm so that it can spit out silk fiber containing spider silk protein.Most of current research on the transgenic silk is about biology and mechanical properties,and the basic research on the structure and properties of transgenic silk are very few,and there is no study on the regenerated materials of transgenic silk.To fully understand the characteristics of transgenic silk,morphology,amino acid composition,aggregation structure,thermal property and mechanical property of new bave containing spidroin,new transgenic degummed silk containing spidroin,normal B.mori bave and normal B.mori degummed silk are compared and analyzed in this paper.In the meantime,the influence on the secondary structure and mechanical properties of the four types of silks after being ultraviolet ageing treatment are studied.Finally,morphology,aggregation structure,thermal property,mechanical property,air permeability and water solubility of transgenic silk fibroin film and normal B.mori fibroin film are compared and analyzed.The results show that:1.Compared with the normal B.mori cocoon,the transgenic cocoon is smaller and the cocoon layer is thinner.It maybe due to the expression of Ma Sp1 in the middle silk gland interferes with the expression and secretion of normal silk fibroin and sericin.The cross-section of transgenic silk was also cylindrical and the surface was smooth,which indicated that the expression of Ma Sp1 did not change the morphology of silk.No matter before and after degumming,the contents of serine,threonine and aspartic acid in transgenic silk were slightly higher than the normal B.mori silk.The contents of glycine,basic amino acid,hydrophobic amino acid and small side group amino acid of transgenic silk were lower than that of normal B.mori silk.2.Compared with the normal B.mori silk,the infrared spectrum and X-ray diffraction peaks of the transgenic silk before and after degumming did not change significantly.The crystallinity of transgenic silk was higher than that of normal B.mori silk.3.The breaking stress and breaking strain of new bave containing spidroin were higher than those of normal B.mori bave.At the same time,the young's modulus and specific work of rupture of new bave containing spidroin were significantly higher than those of normal B.mori bave,indicating that new bave containing spidroin has better rigidity and toughness.4.After 10 days of ultraviolet irradiation,the mechanical properties of normal B.mori bave dramatic declined,and became hard and brittle.After 20 days of treatment,the surface of normal B.mori bave was obviously damaged,and the integrated mechanical properties of the fiber further decreased.Meanwhile,the new bave containing spidroin began to become brittle after 20 days of ultraviolet aging treatment.This means that the ultraviolet tolerance of new bave containing spidroin was better than that of normal B.mori bave.5.After ultraviolet irradiation for different time,the structure and properties of new transgenic degummed silk containing spidroin were similar to that of normal B.mori degummed silk.The results showed that Ma Sp1 was mainly expressed in sericin under the action of sericin promoter,so it changed the structure and properties of transgenic silk sericin.6.The aggregation structure of transgenic silk fibroin film is similar to that of B.mori fibroin film,and both of them are mainly composed of SILK-I structure.The content of SILK-I structure in the transgenic silk fibroin film with glycerol decreased,but the SILK-I structure was still the main component.The aggregation structure of B.mori fibroin film with glycerol is mainly silk-?.7.The surface of transgenic silk fibroin film and B.mori fibroin film are smooth,brittle,soluble in water and low water vapor permeability.After blending of glycerol,a large number of pores were observed on the surface of the transgenic silk fibroin film with glycerol.The breaking strain increased from 2.2% to 38.5%,and the water vapor transmission rate increased by 80%,and almost insoluble in water.The surface of B.mori fibroin film with glycerol did not change obviously after glycerol blending treatment,and the breaking strain increased from 1.9% to 17.7%.In conclusion,the ultraviolet tolerance of new bave containing spidroin is significantly better than that of normal B.mori bave.The toughness and water vapor permeability of transgenic silk fibroin film are better than that of B.mori fibroin film after blending of glycerol.This study shows that the expression of Ma Sp1 in sericin can improve the crystallinity of the sericin of transgenic silk,and make it more resistant to ultraviolet and other effects.So transgenic silk has great potential application value as a new material.