Preparation And Characteristics Of Bilayered Silk Fibroin (SF)/Hydroxyapatite (HA) Porous Composites

Freeze-drying methodology is proposed to fabricate silk fibroin (SF) and hydroxyapatite (HA) bilayered scaffolds for osteochondral tissue engineering in order to achieve an improved integrative bone and cartilage interface needed for this application.Firstly, SF/HA composite was prepared with the mixed suspension of SF and HA which obtained by mould pressing method and NaCl as porogen. SF/HA composite material was characterized using scanning electron microscopy (SEM), X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR).Secondly, the in vitro degradation experiments showed that the SF/HA composite scaffolds had a stable and appropriate degradation rate in the two degradation buffer. The degradation rate was 23.15% in PBS after 12 weeks, but which was 41.82% in the PBS with Protease XIV. Protease XIV was obviously improved the degradation of SF/HA composite.Thirdly, the SF/HA bilayered scaffold which pore structure could be adjusted was prepared by freeze-drying method, and characterized by Electron Microprobe, EDS, XRD, SEM and FT-IR. It indicated that the silk proteins in the SF/HA composite were increasing with increased the content of NaCl through the vacuum method, and the connectivity of two materials were obvious. The pore of the bilayered scaffold was interconnected when the content of NaCl was up to 600%. With silk protein concentration increased, pore density, porosity decreased, and improved the adhesion between the two materials by vacuum method.Lastly, cells adhesion and morphology were analysed by SEM, results showed that SF porous materials and SF/HA composites have good biocompatibility, and cells were able to adhere, proliferate and spread in SF/HA bilayered scaffold. In the priod of culture, the two sides of materials were still adhered well.