Effect Of Adding Nanoparticle In The Diet Of Silkworm On The Structure And Properties Of Silk

Silk as a natural protein fiber has many characteristics,such as porosity,hygroscopicity,excellent mechanical properties,biodegradability and compatibility.With the improvement of living standards,people's demand for differentiated silk products has gradually increased.Improving silkworm seeds to obtain higher-quality silk raw materials,or post-processing silk to obtain high-quality silk products has been the focus of research.In recent years,the structure and performance of silk modified by silkworm breeding method has gradually attracted the interest of scholars in various fields,and also achieved good results.This article uses the diet method to focus on the effects of adding different concentrations and sizes of TiO2 nanoparticles and ZnO nanoparticles on the health and silk structure of silk-worms.The results are as follows:In this paper,different concentrations and sizes of TiO2 nanoparticles and ZnO nanoparticles were added to mulberry leaves and artificial diets to study the effects of different conditions on silkworm and silk.And draw the following conclusions.Mulberry leaves were sprayed with TiO2 nanoparticles of different concentrations and sizes,and modified silk was obtained by the feeding method.In the dosage range(0.05?0.8%)and size range(5-100nm)of this study,the mortality of silkworm was not significantly dinfferent from that of the control group.The fineness of the modified silk added with TiO2 nanoparticles was about 5%smaller than that of the control group,no obvious nanoparticles were observed on the surface of the modified silk,and the basic morphology and structure of the modified silk did not change.However,the ingestion of TiO2 nanoparticles prevented the conversion of ?-helix and random clusters into ?-sheet conformation in silk fibroin,which reduced the crystallinity of the modified silk,and with the increase of the concentration of TiO2 nanoparticles As the size increases,the crystallinity decreases more significantly.The intake of TiO2 nanoparticles improved the mechanical properties of modified silk.The breaking elongation and breaking strength of the modified silk increase with the increase of the concentration of the added TiO2 nanoparticles,and increase and then decrease with the increase of the size of the nanoparticles.When the concentration of TiO2 nanoparticles was 0.8%,the mechanical properties of the modified silk were the best,the elongation at break increased by about 15%,and the breaking strength increased by about 6%.When the size of TiO2 nanoparticles is 40 nm,the mechanical properties of modified silk are the best.The elongation at break is increased by about 14%and the breaking strength is increased by about 16%.Modified silk was obtained by adding TiO2 nanoparticles with different concentrations and sizes to artificial feed.Compared with the case of mulberry leaf feeding,the mortality of silkworms fed with artificial feed was generally increased,and the weight of cocoon shells was significantly reduced.The fineness of the modified silk was not significantly different from that of the control group,but both were smaller than those obtained from mulberry leaves,no obvious nanoparticles were observed on the surface of the modified silk.The addition of TiO2 nanoparticles did not significantly affect the basic morphology and structure of silk.The content of a-helix and random coil conformation of modified silk protein molecules obtained by adding different concentrations of TiO2 nanoparticles in artificial feed increased,the content of ?-sheet conformation decreased,crystallinity decreased,and as the concentration and size of TiO2 increased,The change is more obvious.The intake of TiO2 nanoparticles improved the mechanical properties of modified silk.The breaking elongation and breaking strength of the modified silk increased first and then decreased with the increase of the concentration and size of the added TiO2 nanoparticles.When the concentration of TiO2 nanoparticles is 1.5%,the mechanical properties of the modified silk are the best,and the strength increase is not obvious.When the size of TiO2 nanoparticles is 40 nm,the mechanical properties of the modified silk are the best,and the breaking strength does not change significantly.The maximum elongation at break is 20.0%,which is 29%larger than the control silk.The modified silk with TiO2 nanoparticles has better thermal stability than the control silk.Modified silk was obtained by adding ZnO nanoparticles with different concentrations in artificial feed.The death rate of silkworms increased significantly with the increase of the concentration of ZnO nanoparticles.When the concentration reached 0.8%,all silkworms died.The fineness of modified silk with ZnO nanoparticles was not significantly different from that of control silk,no obvious nanoparticles were observed on the surface of the modified silk.The effect of ZnO nanoparticles on the structure and properties of silk is similar to that of TiO2 nanoparticles.Within the range of concentration that can be added,the effect of ZnO nanoparticles on the strength of the modified silk is not obvious,and the effect on the elongation at break of the silk is significantly increased by 30 to 34%.The modified silk of ZnO nanoparticles has better thermal stability than the control silk.