Microwave Synthesis Of Silk Fibroin-cyclodextrin Slow-release Microspheres And Their Application Of Carvone

Silk Fibroin has many advantages of good biocompatibility and slow-release performance,which is widely applied to medicine,food industry.At the same time,its good degradation efficiency won't cause pollution to the environment.It is one of materials with high efficiency,wide application and sustainable biological activity.However,if only silk fibroin is as sustained release microspheres,its poor hydrophilicity will lead to the phenomenon of burst release at the beginning of the slow-release easily,which can influence seriously release rate.Studies found that Microwave Maillard(Maillard Reaction by Microwave)Reaction can effectively improve the function and nature of silk fibroin.The method not only has the advantages of high efficiency,environmental protection,selective heating,but also avoid effectively the addition of organic solvent and crosslinking agent.This study used the low temperature degassing treatment,separation and purification to degrade silk fibroin,firstly.Then silk fibroin was modified with cyclodextrins(Cd)by the method of microwave wet maillard reaction to get the glycosylated product.At the same time,the different reaction factors were explored according to the free amino acid content and the browning degree.Also,a variety of characterization methods were used to compare that the microwave heating(MW)and water bath(WB)effected on the physicochemical properties and the the structure function of covalent compounds(SF-Cd).Finally,sinistral carvone(Left-Carvon,L-Ca)as the slow-release material was tested to evaluate the sustained-release performance of SF-Cd microspheres by oral simulation.The main research contents and conclusions are as follows:1.A mild degassing treatment at low temperature was chosed to retain greatlybiological activity of silk fibroin.After low temperature degumming and degradation,overlap dialysis method was used to separate and purify fibroin protein,and the yield of the soluble silk fibroin was 24.23%.Through the regular composition analysis,the obtained soluble fibroin protein has high purity and targeted molecular weight,which can be used to research the emulsifying and foaming properties of silk fibroin.At the low concentration,emulsifying performance increased with the concentration of silk fibroin increase,and peaked when the pH at 8.But different pH of silk fibroin has hardly any influence on emulsion stability.Foaming capacity reached the top at 1%of the concentration.When concentration was higher than 0.5%,the foam stability was better.Structure of product was characterized by FTIR,DSC and SEM.2.The Silk Fibroin was modified with the beta cyclodextrin,starch,maltodextrin and agarose by the method of the microwave wet maillard reaction.According to the grafting yield of silk fibroin,the cyclodextrins was chose.At the same time,the effect of ultrasonic power,reaction time,microwave power,ratio of substrates on silk fibroin free amino acid content and the browning degree was explored.The response surface analysis concluded that the optimum synthetic condition of SF-Cd was that SF:?-Cd =2.5:1,the microwave power was 500 W and the reaction time was 4 min.The experiment verified the branch rate was 82.95%.3.A variety of characterization methods were used to compare the physicochemical properties and the structure function of covalent compounds(SF-Cd)that was treated by the microwave heating(MW)and water bath(WB),respectively.The solubility,whiteness,disulfide bond and content of thiol were studied after microwave,and a variety of characterization methods were used to investigate the correlation between the physicochemical properties and the structure function.The results showed that silk fibroin and SF+Cd(WB)have worst solubility at pH=4 and the SF+Cd(MW)has lowest solubility at pH=6.Fluorescence emission spectra showed that the emission wavelength of SF-Cd glycosylation product obtained by microwave is at 429 nm under the condition of the excitation wavelength at 360 nm.The fluorescence intensity of SF+Cd(MW)was significantly higher than that of SF+Cd(WB)and untreated silk fibroin.What's more,the fluorescence intensity enhanced obviously after 3 min,which indicated that the generation rate of SF+Cd(MW)was accelerated 3-4 min and the maillard reaction was more strong.FT-IR spectrum showed that silk fibroin and cyclodextrin generated glycosylation product through carbon ammonia condensation reaction.DSC experimental results showed that the thermal stability of product is good.SEM images found that the surface of silk fibroin got more rough after glycosylation,which was beneficial to the application of adsorption.4.Sinistral carvone(Left-Carvon,L-Ca)as the slow-release material was tested to evaluate the sustained-release performance of SF-Cd microspheres by oral simulation,and the effects of preservatives and pH on its slow-release were explored.The results showed that the load rate of carvone is 8.27%,the encapsulation rate is 80.65%.At oral pH and temperature,the slow-release time can be up to 30 min,and the slow release rate is appropriate.The effects of food additives can be ignored in actual application.The slow-release mechanism of fibroin protein glycosylation microspheres is that the Fickian diffusion,and the product have good biodegradability.