Porous calcium phosphate granules containing drug-loaded polymeric nanoparticles for bone regeneration

A simple and highly efficient method for fabrication of drug-loaded porous calcium phosphate (CP) granules using biodegradable nanoparticles was developed in this study. Porous CP granules were used as a bone graft substitute with a localized drug delivery structure. Spherical CP granules with open micro-channels and PLGA nanoparticles loaded with dexamethasone (DEX) as a model drug were fabricated by a liquid nitrogen method and a single emulsion method, respectively. The produced nanoparticles were pre-coated with positively charged poly(ethyleneimmine) (PEI) molecules and then immobilized via electrical interaction in the micro-channels on the surfaces of CP granules, which have a negative charge. The results indicated that the PEI-coated PLGA nanoparticles loaded with DEX were successfully incorporated and well-dispersed in the micro-channels of the CP granules. The nanoparticles were not released from the CP granules and allowed a sustained release of DEX from the nanoparticle-based CP granules over the course of 1 month.