In this study, the release of phosphorus oxyacid species from organically modified layered zirconium phosphate was investigated. Zirconium phosphate was modified by partially incorporating phenylphosphonate by heating a mixture of phosphoric acid and phenylphosphonic acid under reflux. Characterization by powder X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis confirmed that approximately 50 % of the phosphate groups in the zirconium phosphate framework were successfully replaced by phenyl groups. Upon immersion in Tris-hydrochloric acid buffer for 168 h, both inorganic phosphate and phenylphosphonate were released. In contrast, in phosphate-buffered saline, phenylphosphonate was eluted while inorganic phosphate from the solution was incorporated into the material. These results suggest that zirconium phosphate modified with phenylphosphonate can serve as a potential material for imparting phosphorus oxyacid-based drug-releasing functionality to zirconia-based dental materials.
Kozaki et al. (Sat,) studied this question.