The Preparation Of High-strength Silk Fibroin Film

Silk fibroin as a protein is produced from silkworm cocoon, which has good biocompatibility, biodegradability, non-toxicity cell characteristics, more and more are used in areas of bio-medicine especially tissue engineering. Among them, the silk fibroin film, prepared by the drying of the silk fibroin solution, is the one that was studied first and in the most depth. However, the brittleness and poor mechanical properties of the silk fibroin film limit its applications. To improve the mechanical performances, many researchers have adopted blending, grafting, or crosslinking to prepare mixed the silk fibroin film, This improved the mechanical properties to some extent, but the introduction of alien species led to nonuniform degradation and to a decrease in the biocompatibility, and this narrowed the application scope. This paper aims to find a good solvent for silk fibroin and prepared a higher intensity silk fibroin film. The ionic liquid is considered to be the "21st century green solvents", it became fibroin processing, and integrated application provides new ways and ideas.In this paper, a series of basic ionic liquids were synthesized, and examine the dissolution of ionic liquids with basic amino acids, urea, a mixed solvent of silk fibroin, [Bmim]Ac ionic liquid with good dissolving capacity for silk fibroin was selected. The dissolving properties of silk fibroin in the [Bmim]Ac ionic liquid were researched. Examined the solution temperature, the solution concentration of silk fibroin, the results showed that under 80℃, 900 min, the largest solubility could reach to 18%. The structures of nature and regenerated silk fibroin were characterized by X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FT-IR), the results showed that the silk fibroin is dissolved directly, the silk fibroin in the dissolution process doesn’t derivatization. Therefore, [Bmim]Ac ionic liquid is the excellent solvent for silk fibroin. The dissolve mechanism of silk fibroin in the [Bmim]Ac was analysized.The regenerated silk fibroin films from ionic liquid was prepared by using a spin coater, searched the methanol and ethanol as coagulant which film forming effect is good. With the method of vacuum freeze drying, the regenerated silk fibroin film was of better structure than the traditional film. The regenerated silk fibroin film the methanol as coagulan, the breaking strength 18.74 MPa, swelling rate 44.42%, contact angle 75.9°. The regenerated silk fibroin film the ethanol as coagulan, the breaking strength 15.76 MPa, swelling rate 35.34%, contact angle 78°. In terms of comprehensive, the regenerated silk fibroin film was of better properties than the traditional film. The regenerated film was tested by XRD, FT-IR, SEM and permeability. the results showed that the regenerated silk fibroin film was of better permeability than the traditional film. The structure of the silk fibroin did not change significantly before and after the dissolution.Using two-film sandwich method of silk fibroin membrane regeneration to release the drug. The results showed that, drug-loaded silk fibroin membranes at pH 3.5 disodium hydrogen phosphate-citric acid buffer solution is best released. At pH3.5, 70 min, the drug delivery of traditional film is maximum, the release rate is 66%. Drug delivery of ionic liquid regeneration film is slower than that of the traditional film. At the beginning of 100 min, drug release up to a maximum, the release rate is 80%. In this study, the drug sustained-release film of silk fibroin investigation for the future fibroin film applications in the medical field to provide a reference value. The investigation about the drug sustained-release film of silk fibroin provide a reference value for the future fibroin film applications in the medical field.