Hydrothermal fabrication of magnetic mesoporous carbonated hydroxyapatite microspheres: biocompatibility, osteoinductivity, drug delivery property and bactericidal property

Implant-associated infection is a serious problem in orthopaedic surgery. Ideal bone filling materials should not only possess excellent biocompatibility, but also have good anti-infection property and osteoinductivity. Herein, magnetic mesoporous carbonated hydroxyapatite microspheres (MHMs) have been fabricated according to the following stages: (i) preparation of CaCO3/Fe3O4 microspheres; and (ii) hydrothermal transformation of magnetic calcium carbonate microspheres into MHMs. MHMs possess well-defined 3D nanostructures constructed by nanoplates as building blocks. The mesopores and macropores exist in and among the nanoplates, respectively. The porous structure makes the MHMs possess a great drug loading efficiency of 73-82%. Gentamicin-loaded MHMs display a sustained drug release property, and the controlled release of gentamicin can prevent biofilm formation against S. epidermidis. Moreover, the MHMs possess a magnetic property with a saturation magnetization strength of 3.98 emu g(-1) because Fe3O4 nanoparticles are dispersed in the microspheres. The in vitro cell tests indicate that the magnetic nanoparticles in the MHMs not only promote the cell adhesion and proliferation of human bone marrow stromal cells (hBMSCs), but also stimulate the osteogenic differentiation. MHMs exhibit excellent biocompatibility, osteoinductivity, drug delivery property and bactericidal property, so they have great application potential for the treatment of complicated bone defects.