Composite Silk Materials Containing Multi-angle Silk Fibers

The aim of the thesis is to fabricate silk composite films containing degummed silkfibers that are orientated at different angles on multiple layers. The silk fibroin structuralchanges, mechanical properties, proteolytic degradation and cell responses of thecomposite materials have been studied in order to demonstrate the feasibility of theirpotential applications in biomedical applications, such as engineering of artificialmeniscus.Fourier transform infrared spectroscopy.(FTIR) and x-ray differentiation (XRD)analyses indicated that the presence of degummed silk fibers at different angles did notsignificantly change the secondary structure and crystallization of the hosting silk films, ascompared with silk films alone.The composite silk films in dry and wet states showed significantly differentmechanical properties. The mechanical strength (stress) and elongation property (strain) ofthe dry films are better than those of the wet films. The angles at which fiber layers weresuperimposed also largely influenced the mechanical properties of the composite materials.When the direction of the pulling was along the fiber orientation (parallel), the strengthmeasured (50-60MPa) was larger than those pulled from other orientations (3-6MPa). Amore even strength of18MPa was measured when the angle was set at30°.The proteolytic degradation of silk films was determined using1IU/ml protease XIV.Pure silk films were completely degraded within48hours, while the degradation of thefiber-reinforced composite silk films was much slower, with28%of original mass (mainlyembedded fibers) remained after eleven days. The superimposed fiber layers with an angleof90°to each other lost more structures than those with30°and60°angles. The30°superimposed materials were more stable than the0°and90°samples.In the cell culture study, In order to verify the safety of the composite materials,Studies the toxic of the composite materials, the incorporation of degummed fibers may beinfluence the biocompatibility of silk films.Since the composite silk films exhibited structures and mechanical propertiescomparable to the force-bearing layer of natural meniscus, they hold great promise in the tissue engineering applications in the future, such as fabrication of artificial meniscus.