2010 Volume 24 Pages 54-61
Porous spherical hydroxyapatite (Ca10(PO4)6(OH)2: HAp) agglomerates with diameters of approximately 1 µm were prepared by: (i) the spray-pyrolysis of calcium phosphate solution containing 0.5 mol dm-3 Ca(NO3)2, 0.3 mol dm-3 (NH4)2HPO4, 0.1 - 0.4 mol dm-3 glutaric acid and concentrated HNO3 at 600°C, using an ultrasonic vibrator, and then (ii) the burnout of residual carbon resulting from the pyrolysis of glutaric acid upon the heat treatment of the spray–pyrolyzed powder at 900°C for 10 min. Three types of resulting HAp powders were then hydrothermally treated with 1.5 mass% β-cyclodextrin (β-CyD) solution at 120°C for 1 h. The amounts of β-CyD in the resulting HAp agglomerates were found to be in the range of 1.1 to 13.1 mass%. Transmission electron microscopy confirmed the presence of β-CyD not only on the surfaces but also inside the spherical HAp agglomerates. When the HAp powder with 13.1 mass% β-CyD addition was immersed in pure water at 90°C for 1 h, the released amount of β-CyD was as low as 2.1 mass%, indicating the enhanced chemical bonding between β-CyD and HAp, due to the hydrothermal treatment.
