Preparation And Characterization Of The Silk Fibroin Films And Hydrogels In Different Salt/formic Acid Dissolution System

Silk fibroin is a kind of macromolecular materials with good biocompatibility and biodegradability, by regeneration method silk fibroin can be made into different different traits such as silk films and hydrogels,which is widely used in tissue engineering, drug slow Buddhism and other biological high-tech fields. However, the traditional preparation of regenerated silk fibroin material performance is poorer, fibroin membrane water content is low, high brittleness and dense space;And fibroin gel water high water cut, but single morphology structure, mechanical properties and often could not reach the requirements of biomedical, makes the regenerated silk fibroin materials limited.In this paper, new salt/formic acid solvent systems are used to dissolve silk and prepare silk films in order to explore how different types of salt influence the silk solution, structure and properties of silk films and hydrogels.Firstly, this paper prepare silk solution by changing the type（CaCl₂、CaBr₂、LiBr）and concentration of salt（2 wt%,4 wt%,6 wt%） in formic acid, the result shows that nanofibers appear in salt/formic acid dissolution system, the nanofibers prepared in CaCl₂/HCOOH solution are more under the same concentration, the silk fibroin nanofiber length and diameter vary as the salt change,the diameter of the nanofibers is finer when the concentration is higher. The gel-like films prepared by salt/acid formic contain a lot of water, the gel-like films present β-sheet structure while the structure of the films dissolved in 9.3 M LiBr aqueous solution contain α-helix and random coil.Corresponding to the solution, the gel-like films contain nanofiber. The hydrogels made by salt/acid formic contain high water content, the hydrogels show a β-sheet structure,the mechanical property of hydrogel is better, compression modulus of hydrogel containing 20 wt% silk fibroin which dissolved in CaCl₂/HCOOH system is up to 6.02 MPa, indicating the future specific applications of the hydrogels.