One-step hydrothermal synthesis of carbonated hydroxyapatite porous microspheres with a large and uniform size regulated by L-glutamic acid

The understanding of the role of acidic amino acids in the synthesis of calcium phosphate (Ca-P) may provide effective ways for the design of advanced biomaterials. In this work, by employing L-glutamic acid (Glu), a one-step hydrothermal synthesis of porous carbonated hydroxyapatite (CHA) microspheres with high purity, good uniformity, controllable morphology, and large particle size is proposed. The morphology is well controlled by adjusting the concentration of Glu and the hydrothermal treatment time. The presence of Glu alters the growth pattern of Ca-P products and leads to the evolution of particles from ribbons to flower-like microspheres due to adsorption and the subsequent inhibiting action of the active growth sites onto the CHA's surface. It is established that the optimal condition having a predominance of uniform microspheres with an average diameter of about 64 mu m is a Glu concentration of 0.06 M (at a Ca2+ : PO43- : Glu molar ratio of 10.8 : 6 : 15). The CHA microspheres may be possibly used as effective carriers for biomedical application.