Investigation of the crystallinity change after the addition of magnesium hydroxides into the calcium phosphate during mechanochemical synthesis: an FTIR spectroscopy, XRD analysis, chemometrics, and cell culture

The aim of this study is to investigate the effect of the addition of Mg ion on calcium phosphate during mechanochemical synthesis. Ca(OH)2, dicalcium phosphate dihydrate (DCPD), and Mg(OH)2 were mechanochemically synthesized using ball milling with pure water. The prepared samples were evaluated by powder X-ray diffraction analysis (XRD), FT-infrared (IR) spectral analysis, and a TNF alpha test with murine macrophage-like cell line RAW264.7 cells for assessing the immune activation. The cell culture studies indicated that CaMg apatite can be used as bioceramic. Mg ion-doped Ca apatite, which also contains carbonated ions in the crystal, was identified based on the XRD patterns and FTIR spectra. The unique diffraction peaks of apatite at 211, 112, 300, and 202 decreased in the sample containing Mg(OH)2, suggesting a decrease in the rate of crystallization. In addition, the phosphate infrared bands of the samples were different from those of the carbonated apatite. To investigate the details of the effects of Mg ion, multiple spectra combining XRD patterns and FTIR spectra were prepared. The multiple spectra datasets were used for the estimation by multivariate curve resolution-alternating least squares (MCR-ALS). The effects of Mg ion on apatite as calcium phosphate were investigated by multiple spectra multivariate analysis. The analysis postulated that Mg ion decreased the apatite crystallinities possibly by adsorption at the growth sides and that these added ions strongly inhibited the formation of the thermodynamically most stable hydroxyapatite.