Tissue distribution of intravenously administrated hydroxyapatite nanoparticles labeled with 125I

Hydroxyapatite nanoparticles (HANPs) have been developed for biomedical use due to the extraordinary properties. However, sometimes biomedical use of HANPs could cause side effects. As the biosafety of nanotechnology becomes a growing concern, the behavior of HANPs in vivo has been paid much attention to. This study was to establish a method of ¹²⁵I radiolabeling, investigate the long-term quantitative tissue distribution of HANPs after intravenous administration using radiolabeling and the subcellular distribution in liver and spleen by TEM. The results indicated HANPs could accumulate mainly in the Hver and spleen and retain for over 28 days. This stagnation most probably attributed to the endocytosis by macrophages in these tissues. It suggested that the biosafety of liver and spleen should be concern even more when HANPs were applied.