Preparation of apatite microsphere with nano-size pores on the surface via salt-assisted ultrasonic spray-pyrolysis technique and its drug release behavior

To apply biodegradable calcium-phosphate microspheres as a carrier for drug delivery system (DDS), the hollow HAp and TCP microspheres were prepared by the ultrasonic spray-pyrolysis (USSP) technique. In the present work, we prepared the hollow bioceramics microspheres with nano-size pores on the surface via a salt-assisted USSP technique on the basis of previous findings. Diameters of the microspheres were in the range of 0.5 to 3.0 μm, and the nano-pores with the size of ∼50 nm were present on the surface of the microspheres. The loaded amount of the drug depended on the specific surface area (SSA) value of the microspheres; the washed powders derived from the NaCl concentration of 1.00 mol · dm^-3 showed the greatest amounts of released drug among examined sample powders. The microspheres with nano-size pores on the surface showed a two-step drug release behavior.