Effect of pH on the fibroin regulated mineralization of calcium phosphate

The effect of pH on the mineralization of calcium phosphate regulated by fibroin is investigated in this paper. Calcium phosphates were prepared under different pH of the solution. The products were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results demonstrated the great influence of pH on the formation of calcium phosphate, both in the presence and in the absence of fibroin. Pure hydroxyapatite (Ca10(PO4)6(OH)2,HA) can be obtained at relatively high pH (pH 8.0), while brushite (CaHPO4 · 2H2O, DCPD) is the usual product at low pH (pH 4.0, 5.2) in 10 h. Additionally, the presence of the fibroin can accelerate the transformation from DCPD to HA and regulate the morphology and structure of the HA crystals obtained.