Preparation and characterisation of calcium-phosphate porous microspheres with a uniform size for biomedical applications.

In the present work, a novel route for the preparation of porous ceramic microspheres is described. Two ceramic powders, calcium-titanium-phosphate (CTP) and hydroxyapatite (HAp), were mixed with a sodium alginate solution that enabled the preparation of spherical particles, using the droplet extrusion method combined with ionotropic gelation in the presence of Ca(2+). The spherical particles were subsequently sintered, to burn-off the polymer and obtain calcium-phosphate microspheres with a uniform size and an interconnected porous network. CTP microspheres with diameters ranging from 513 +/- 24 microm to 792 +/- 35 microm and with pores of approximately 40 microm were obtained. HAp microspheres presented diameters of 429 +/- 46 microm and 632 +/- 40 microm and pores of ca. 2 microm. Depending on the formulations tested, the structure of both calcium phosphates may become altered during the sintering process, suggesting that the ratio between the ceramic phase and the polymer solution is a critical parameter. Porous microspheres prepared using the described methodology are promising candidates as bone defect fillers and scaffolds for bone tissue regeneration.