Hydrothermal fabrication of mesoporous carbonated hydroxyapatite microspheres for a drug delivery system

Mesoporous carbonated hydroxyapatite microspheres (MCHMs) with a particle size of ∼5 μm have been fabricated hydrothermally by soaking calcium carbonate microspheres (CCMs) in a disodium hydrogen phosphate solution at 140 °C. The transformation mechanism is a dissolution–precipitation reaction. After soaking in the disodium hydrogen phosphate solution, the calcium ions released from the CCMs react with phosphate ions in the solution to form carbonated hydroxyapatite nanoparticles. These nanoparticles aggregate to form mesopores with the pore size of 4.0–14.0 nm. The MCHMs have been tested as vancomycin delivery systems due to the presence of the OH units in the carbonated hydroxyapatite structure, which provide these carriers of great affinity towards host drug molecules. In addition, in vitro tests into a simulated body fluid (SBF) demonstrate that the MCHMs are bioactive, since an apatite layer deposits on their surfaces after 3 days of assay. Such MCHMs could be useful in developing new biomaterials and have potential use in implanting and drug delivery for tissue regeneration.

TEM image of carbonated hydroxyapatite microspheres converted from carbonate calcium microspheres by hydrothermal method.Figure optionsDownload as PowerPoint slideHighlights
► Mesoporous hydroxyapatite microspheres are fabricated by hydrothermal method.
► The formation mechanism is a dissolution–precipitation reaction.
► These microspheres are promising for local drug delivery systems.