Silk Fibroin/Sodium Alginate Composite Film and Hydroxyapatite Mineralization

Abstract

Silk fibroin/sodium alginate blend films and its hydroxyapatite deposition were prepared and characterized by scanning electron microscopy, wide angle X-ray diffraction, Fourier transform infrared analysis, and thermal analysis. The surface of blend films showed much more rod-like structure dispersing uniformity and its average length increasing from 181 to 803nm with increasing the contents of sodium alginate. The crystal structure of silk fibroin and the compatibility of the two components were associated with the content of sodium alginate in silk fibroin/sodium alginate blend films. The silk I and silk II crystal structures of silk fibroin were co-existed in the blend films and a rather complex conformation transition occurred, which was confirmed by wide angle X-ray diffraction and Fourier transform infrared analysis. Thermal behavior of blend films was interrupted by adding different contents of sodium alginate. Adding 30.0% sodium alginate or more, the endothermic peak of moisture evaporation shifted downward from 111 to 80°C, and the degradation peaks at 243 and 279°C, respectively, indicating an obviously two phase structure in the blend films. In addition, the rod-like HAp crystals were grown on the surface of blend films. This result may provide some new ideas in the design and fabrication of new materials through the silk fibroin/sodium alginate composite materials template for the hydroxyapatite crystal growth.