Microwave-assisted Extraction Of Silk Fibroin And Studies On Its Hydrogel

Silk fibroin hydrogel is a biomaterial with a wide range of applications.At present,the common method to extract regenerated silk fibroin is to dissolve silk fibroin in a series of solvents by heating in a water bath,which is time-consuming and energy-consuming.In view of the unique heating method of microwave heating technology,this thesis studies the application of microwave technology in the extraction of silk fibroin,and improves the mechanical properties of silk fibroin hydrogel.First,this thesis investigated the effects of microwave and water bath heating methods and Ca(NO3)2/CaCl2:CH3CH2OH:H2O(1:2:8)systems on dissolution efficiency and properties of regenerated silk fibroin.The experiment investigated the effect of microwave on the dissolution efficiency by monitoring the change of protein concentration with dissolution time;fourier transform infrared spectroscopy(FTIR)and sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE)were used to study the effects of microwave on molecular weight,amino acids composition and secondary structure of regenerated silk fibroin;the rheological and tensile tests of silk fibroin hydrogels were carried out to investigate the effect of microwaves on the gelation ability of regenerated silk fibroin.The results show that,in the Ca(NO3)2 system,the microwave assisted method can increase the disso\ution efficiency from 36.8%to 54.7%;in the CaC12 system,the microwave assisted method can shorten the dissolution time from 1 h to 10 min;the regenerated silk fibroin obtained by the two methods has a wide molecular weight distribution,and the secondary structure and amino acid composition are almost the same;there is no difference in the storage modulus and loss modulus of silk fibroin physical hydrogel,and the Young's modulus of chemically crosslinked hydrogel is about 75 kPa.After calculating the energy consumption of the two methods,it was found that the microwave assisted method can save more than 90%of the electric energy.Second,in order to improve the mechanical properties of pure silk fibroin hydrogel,in this thesis,physical crosslinks hydrogel formed by electrostatic interaction between Laponite and polyarginine(Poly-Arg)was introduced into chemical cross-linked silk fibroin hydrogel to prepare interpenetrating network silk fibroin hydrogel with good strain capacity and self-healing ability.The internal structure,strain ability,self-healing ability and water retention capacity of the interpenetrating network silk fibroin hydrogel were investigated by scanning electron microscopy(SEM),tensile,compression and swelling tests.The experimental results showed that after the introduction of physical cross-linked hydrogel,the microstructure changes from microporous structure to layered structure;tensile strain increases from 30%to 100%;compressive strain increases from 40%to 70%;shrinkage rate from 15%is shortened to 8%.In this study,a new method of extracting soluble silk fibroin with high efficiency and energy saving was developed and an interpenetrating network silk fibroin hydrogel with excellent mechanical properties and self-healing ability was prepared,which provided basic parameters and guidance for microwave technology in extracting regenerated silk fibroin and preparing self-healing silk fibroin hydrogel.