Nanoemulsion synthesis of carbonated hydroxyapatite nanopowders: Effect of variant CO32−/PO43− molar ratios on phase, morphology, and bioactivity

Abstract Bone is a composite material containing carbonated hydroxyapatite (CHA) nanocrystallite and protein matrix. Low-temperature synthesis and assessment of the in vitro response of CHA nanopowders were conducted. Samples of CHA nanopowders were considered for their phase system, chemical compound, and reactions in a simulated body fluid (SBF). The crystallite size and phase for the CO 3 2− /PO 4 3− molar ratios of 0.67 and 1.00 were examined through X-ray diffraction (XRD). Chemical distinctiveness was analyzed by Fourier transform infrared (FTIR) spectroscopy. The compositions of the as-synthesized powders were quantified by X-ray fluorescence, and the carbon contents were estimated by carbon hydrogen nitrogen analysis. The morphology and textural properties were examined by field-emission scanning electron microscopy, transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) analysis. In vitro study was conducted in SBF medium, and the pH was intermittently recorded. Then, the dissolution of Ca 2+ and PO 4 3− in SBF was quantified by inductively coupled plasma optical emission spectroscopy. The outcomes of XRD and FTIR confirmed that pure single-phase B-type CHA without any secondary phase was formed. CHA .67 showed a crystallite size of (Scherrer) 22.7 nm, particle size by TEM ( P TEM ) of 24.87, and BET ( P S BET ) of 26.48 nm. Meanwhile, CHA 1.00 achieved a crystallite and particle size of (Scherrer) 4.67, P TEM of 6.50, and P S BET of 13.23 nm. Results indicated that increasing the CO 3 2− /PO 4 3− molar ratio decreases the crystallite size and increases the amount of CO 3 2− . Thus, we concluded that the nanoemulsion-synthesized CHA exhibits a crystallite size and chemistry comparable to those of biological hard tissue.