Study On Electrospun Regenerated Silk Fibroin Nanofibers

Electrospinning is a simple and efficient technique for the production of nanoscale fibers. Under high voltage and static electric field, a charged jet is created from a polymer melt or solution when the electrical force overcomes the surface tension of polymer solution, then the solvent evaporates and nanofibers solidify. Finally, the nanofibers are deposited randomly on the surface of the collection plate in the form of non-woven nanofiber membranes. Because of the morphology feature of small diameter, high surface area to volume ratio and high porosity, they can be used as highly porous cell-growth scaffolds for improving cellular migration and proliferation, and also can be used as vascular grafts, wound dressings and drug delivery. They are applied in tissue engineering and biomedical engineering extensively. Silk fibroin is resourceful and has good performance as biomaterials. Many researches indicate that Silk fibroin has several distinctive properties such as good biocompatibility, good oxygen and water vapor permeability and biodegradability, to which much attention has been paid domestic and abroad. The breakthrough of conventional silk fibroin film and application of electrospinning technology can produce fiber membrane which has three-dimentional structure and high surface area to volume ratio. This kind of fiber membrane is expected to be applied in tissue engineering, such as cell-growth scaffolds and wound dressings and so on. This thesis made a preliminary research on the electrospinning of regenerated silk fibroin by the self-designed electrostatic spinning instrument, using formic acid as solvent. It investigated the electrospinning conditions of different silk fibroin membranes. Moreover, it focused on studying the electrospinning condition of air-dried regenerated silk fibroin membrane. We researched the influence of the solution concentration, voltage, electrospinning distance, the nozzle's diameter and spinning angle on fibers'morphology and structure. At the same time, the microstructure of electrospun silk fibroin nanofibers was also tested and analyzed by means of X-ray diffraction,IR spectra,CP/MAS NMR and DSC. The results showed that the process parameters had a crucial effect on the nanofibers'morphology, the nanofibers with average diameter of 91 and 96nm could be produced respectively under the electrospinning solution concentrations of 11 and 13%, the voltages of 32kv and the electrospping distance of 7cm, meanwhile the electrospun regenerated silk fibroin nanofibers had the transitions into β-sheet and the crystallinity increased, compared with the air-dried regenerated silk fibroin membrane. Furthermore, the methanol-treated electrospun SF fibers had a more intense trend intoβ-sheet.