Microwave-assisted hydrothermal rapid synthesis of amorphous calcium phosphate nanoparticles and hydroxyapatite microspheres using cytidine 5′-triphosphate disodium salt as a phosphate source

• Amorphous calcium phosphate nanoparticles are synthesized.
• Hierarchically nanostructured hydroxyapatite solid/hollow microspheres are prepared.
• Rapid microwave-assisted hydrothermal method is adopted.
• Biocompatible cytidine 5′-triphosphate disodium salt is used as a phosphate source.

Calcium phosphates are important biomaterials for biomedical applications. Herein, we report microwave-assisted hydrothermal rapid synthesis of amorphous calcium phosphate (ACP) nanoparticles and hydroxyapatite (HAP) microspheres using cytidine 5′-triphosphate disodium salt as a phosphate source. This synthesis method does not need any surfactant and is very rapid (1 min at 150 °C). The pH value has a significant effect on the morphology and crystallinity of the product. Aggregated ACP nanoparticles, hierarchically nanostructured solid HAP microspheres and hollow HAP microspheres are obtained at pH 7.0, 5.0 and 4.3, respectively. The as-prepared products are characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analysis.