Effect of degumming degree on the structure and tensile properties of RSF/RSS composite films prepared by one-step extraction

Regenerated silk fibroin (RSF) and regenerated sericin (RSS) have attracted much attention for tissue engineering due to excellent biocompatibility and controllable degradation. However, pure RSF films prepared by existing methods are brittle, which limits applications in the field of high-strength and/or flexible tissues (e.g. cornea, periosteum and dura). A series of RSF/RSS composite films were developed from solutions prepared by dissolving silks with different degumming rates. The molecular conformation, crystalline structure and tensile properties of the films and the effect of sericin content on the structure and properties were investigated. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction results revealed more β-sheets in films prepared by boiling water degumming than in Na(2)CO(3)-degummed RSF(C) film. Analysis of mechanical properties showed that the breaking strength (3.56 MPa) and elongation (50.51%) of boiling water-degummed RSF/RSS film were significantly increased compared with RSF(C) film (2.60 MPa and 32.31%), and the flexibility of films could be further improved by appropriately reducing the degumming rate.