(The Key Laboratory of Molecular Engineering of Polymers of the Ministry of Education of China, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai 200433)
The directional freezing followed by freeze-drying techniques was used to successfully prepare regenerated silk fibroin (RSF) scaffolds with directional morphology and considerable mechanical properties. In order to investigate pH and concentration effect of the initial RSF solution on the morphology and mechanical properties of the scaffold, different methods, including the scanning electron microscopy, rheology, Raman spectroscopy, and mechanical test, were conducted. The results show that the morphology of the scaffold changes from fibrils to lamellar structures and then to cellular structures as the initial concentration of RSF solution at pH 4.4 increases. The RSF scaffolds with initial concentration of 15% or above show good mechanical properties, and the axial compression modulus is 122.6 MPa and the yield strength is 6.9 MPa. This would make the directional RSF scaffolds possible for further applications.