Abstract
Hydroxyapatite (HAp) microcrystals were synthesized by a neutralization reaction of Ca(OH)2 suspension and H3PO4 solution using an ultrasonic homogenizer. The characterizations of HAp microcrystals were investigated by XRD, SEM and electroconductivity. HAp microcrystals consisted of a single phase of HAp, dispersed homogeneously and showed a remarkable increase in the initial solubility. Effect of the solubility of HAp microcrystals on the morphology of rat peritoneaafl macrophages was investigated by cell culture test. Ca, Mg and P concentrations in the media and the intracellular Ca contents were measured and morphological changes were observed by TEM and phase-contrast microscopy. Ca concentration in media cultured with HAp microcrystals decreased rapidly, but Mg and P concentrations did not change. Macrophages actively phagocytosed HAp microcrystals and formed ruffling membranes. HAp microcrystals were dissolved inside macrophages and the intracellular Ca content increased. The higher solubility of HAp microcrystals was related to morphological changes in the macrophages.
