Porous and hollow hydroxyapatite microspheres: Synthesis and application in pH-responsive drug release

Hydroxyapatite (HA) microspheres exhibit excellent biocompatibility and degradability, making it widely used as a drug carrier to achieve better therapeutic effects. In this study, porous and hollow HA microspheres with good dispersibility were prepared using calcium carbonate microspheres as a template by a hydrothermal method. The microstructure and composition of the as-prepared HA microspheres were systematically investigated and the formation mechanism of the microspheres were discussed. In addition, an effective anticancer agent doxorubicin hydrochloride (DOX) was used as a model drug to investigate the drug-loading and release properties of HA microspheres. The drug release from HA microspheres exhibits strong pH- dependence with accelerated drug release in acidic environments, making them suitable for tumor-targeted therapy. The cumulative drug release rates of hollow and porous HA microspheres at 21 days in pH 5.0 buffer were 63.2 % and 53.8 %, respectively. This study reported an easy and novel approach to prepare porous and hollow HA microspheres, which provides new strategies for clinical drug delivery by modulating their structural.