Synthesis of solid micro-spherical hydroxyapatite by hard-template method: optimization and characterization

Abstract

Spherical hydroxyapatite (SHAP) has been widely concerned because of its non-toxicity, biocompatibility and unique adsorption capacity. We optimized the synthesis of SHAP using spherical calcium carbonate (CaCO₃) as a template to provide reference for its efficient preparation and application. The optimal synthesis conditions of CaCO₃ are initial salt concentration 0.4 M, PVP concentration 1.0 g/L, stirring 60 min with 700 rpm under 35 °C. Under the optimal conditions, the SEM morphology of SHAP is characterized by spherical particles of uneven surface with a uniform particle size distribution (7.402 μm, D₅₀), porous characteristics and large specific surface area (55.85 m²/g). In addition, SHAP has a high degree of matching with JCPDS no. 09-0432, has a good HAP crystal form, and has high crystal purity. The microstructure and uniform size of SHAP are the basis of its excellent performance, and the above performance parameters of the products in this study are comparable to or even better than some natural HAP and HAP synthesized using different strategies.