Effect of Surface Functional Groups and Calcium Ion Adsorption on Formation of Polystyrene/Apatite Core–Shell Microspheres by Aqueous Solution Method

If a method for developing organic polymer/apatite core–shell microspheres encapsulating organic polymer microspheres with apatite shells can be constructed, it is possible to establish a fundamental methodology to fabricate apatite capsules for drug delivery carriers. In this study, polystyrene (PS) microspheres were used as model substances in organic polymer microspheres, and the effects of the surface functional groups on the PS microspheres on the amount of Ca2+ ions introduced onto the PS microspheres were investigated. The PS/apatite core–shell microspheres were prepared by immersing Ca2+-incorporated PS microspheres in a reaction solution containing Ca2+, HPO42−, and Mg2+ to coat the surface of PS microspheres with apatite. Particle characterization of the prepared PS/apatite core–shell microspheres was performed, and the relationships among the surface functional groups, surface potential, Ca2+ adsorption, and apatite shell formation in the aqueous solution on the PS microspheres were investigated.