The synthesis of hydroxyapatite with different crystallinities by controlling the concentration of recombinant CEMP1 for biological application

Cementum protein 1 (CEMP1) has been reported to be cementum specific and it plays a role in the properties and structure of cementum mineralization. This study was carried out to test the hypothesis that, CEMP1 had the capacity to guide ordered HA formation as it accumulated at targeting site. Crystals induced by protein were prepared by biomimetic method. The effects of CEMP1 concentrations (0-100 μg/ml) on the rate of calcium phosphate precipitation was monitored during 48 h, while the formed mineral phases were assessed utilizing transmission electron microscope (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results showed that recombinant cementum protein 1 (rhCEMP1) affected the crystal nucleation and growth. At lower rhCEMP1 concentrations (0-50 μg/ml), limited mineral formation occurred and only small bundles of HA crystals were found. However, with 100 μg/ml of rhCEMP1, a predominance of organized linear needle-like HA crystals was observed. FTIR revealed the characteristic bands of HA appearing at 1106 cm− 1, 557 cm− 1, and 598 cm− 1. Therefore, increasing the concentration of rhCEMP1 can lead to the formation of ordered bundles of HA crystals in vitro.