Synthesis and Characterization of Copper Ions Doped Octacalcium Phosphate Powders with Enhanced Osteogenic Property

Diverse biomaterials have been designed to promote bone regeneration, and due to their potential side effects of adverse inflammation and immune responses, only a few synthetic biomaterials displayed successful clinical outcomes in repairing bone defects. The repair of bone defects remains a big challenge for orthopedists. This study was dedicated to the synthesis of copper-doped octacalcium phosphate powder Cu-OCP with good bone repair potential, which provides a new way for the construction of bone regeneration biomaterials. Five kinds of copper-doped powders, OCP, 0.1Cu-OCP, 0.5Cu-OCP, Cu-OCP and 5Cu-OCP, were synthesized by chemical homogeneous precipitation method. The phases of the powders were analyzed by X-ray diffraction (XRD). The elemental compositions of the powders were analyzed by X-ray fluorescence spectrometer (XRF). The microstructures of the powders were observed by scanning electron microscopy (SEM). Inductively coupled plasma atomic emission spectrometry (ICP) was used to determine the 24-hour cumulative release of copper ions in Tris solution. The biocompatibility of the powders was measured by CCK8 and live/dead staining. The effect of the powders on bone differentiation was measured by ALP activity. the OCP powder was a long strip chip like crystal structure under SEM. The doping of Cu2+ made the chip structure smaller and finer. The main diffraction peak of OCP can be seen at 2θ=4.7° for all the five powders. XRF showed that the main composition of the powders was still Ca, P and O. The mass fractions of Cu2+ in the powders were 0.1Cu-OCP: 0.02%, 0.5Cu-OCP: 0.08%, Cu-OCP: 0.23%, and 5Cu-OCP: 0.76%, respectively. ICP results showed that Ca, P and Cu were released slowly in 24 hours in Tris solution. CCK8 and live/dead staining showed that all kinds of copper-doped OCP powders had good biocompatibility with mBMSCs, and could promote osteogenic differentiation. Among them, 0.5Cu-OCP promoted the proliferation and ALP activity of mBMSCs significantly. In conclusion, in this study, copper ions were successfully doped into OCP powder, and the physical and chemical properties of OCP powders doped with copper ions were characterized. In vitro cell experiment confirmed that the powders had good biocompatibility, non-toxic to mBMSCs, and could promote the proliferation of mBMSCs in vitro.