Microwave-assisted synthesis of hydroxyapatite hollow microspheres in aqueous solution

We report a template-free microwave-assisted hydrothermal method for the preparation of hydroxyapatite hollow microspheres constructed by the self-assembly of nanosheets using Ca(CH(3)COO)(2), Na(2)HPO(4), NaH(2)PO(4) and sodium citrate in aqueous solution. X-ray powder diffraction (XRD) patterns indicated that the as-prepared samples consisted of hydroxyapatite. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) micrographs showed that the as-prepared products were composed of hollow microspheres assembled with nanosheets and had three-dimensional nanoporous nanostructured networks. The experimental parameters were varied to investigate their effects on the product, and a possible formation mechanism was proposed. The as-prepared hydroxyapatite hollow microspheres have a potential application in drug delivery. (C) 2011 Elsevier B.V. All rights reserved.