Synthesis of Magnesium Doped Amorphous Calcium Phosphate as a Bioceramic for Biomedical Application: In Vitro Study

In this study, the effect of addition of magnesium as a stabilizer of amorphous phase on the structure and bioactivity of amorphous calcium phosphate for biomedical applications was investigated. Therefore, amorphous calcium phosphate was synthesized by a precipitation and freeze drying method with different molar ratios of magnesium to calcium (Mg/Ca). Then the samples were incubated in simulated body fluid (SBF) for 3, 7 and 14 days to evaluate their bioactivity and the investigation of their phase conversion. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy were employed to characterize the prepared samples. According to X-ray diffraction patterns, the most stable amorphous phase was obtained at a magnesium to calcium (Mg/Ca) ratio of 0.3 and the magnesium acted as a stabilizer of the amorphous phase. After incubation in SBF solution, the hydroxyapatite phase was detected in XRD patterns of the samples, but with the addition of the magnesium, the crystallinity and formation of the hydroxyapatite phase was decreased. Also the FTIR analysis showed that the intensity of the peaks related to phosphate and hydroxyl groups decreased with the addition of magnesium, which indicated a more stable amorphous calcium phosphate phase. Finally, in-vitro experiments like MTT assay and alkaline phosphatase activity with human osteosarcoma cell lines (G-292) on the prepared samples were evaluated and discussed. The results indicated that amorphous calcium phosphate with a calcium to magnesium ratio of 0.3 revealed optimal cell proliferation and ALP activity. Eventually, this material is non-toxic and compatible to be used as a bone substitute material.