Effect of Pretreatment on Fabrication of Natural Fibroin Fiber/Apatite Composites Using Alternate Soaking Method

To develop biomimetic fibroin/apatite composites with bone-like structure by alternate soaking method, the degummed natural fibroin fibers were pretreated by soaking into CaCl_2:EtOH:H_2O(n(CaCl_2):n(EtOH):n(H_2O)= 1:2:8) solution for given time and then soaked into calcium solution and phosphate solution,respectively,to fabricate fibroin /apatite composites.The effects of pretreatment time and the alternate soaking times on fibroin microstructure and fibroin/apatite composites were examined by SEM,FTIR,XRD and TGA techniques.The pretreatment using CaCl_2:EtOH:H_2O(n(CaCl_2):H(EtOH):n(H_2O)=1:2:8) solution makes fibroin fiber exhibit rougher surface and higher internal porosity,which is beneficial to interaction of calcium ion and residue groups such as -COOH,-OH and -CONH- from fibroin,and then improve the deposition of apatite on fibroin fibers.The homogeneous apatites with oriented c-axis were formed on the pretreated fibroin fibers.Moreover,there are more than 30wt%apatites deposited on fibroin fibers after alternate soaking for more than 3 times.The fibroin/apatite composite has potential to be applied as bone repair materials.