Internal distribution of micro-/nano-sized ceramics and metals particles in mice

Internal distribution of several nanoparticles in mice has been investigated using scanning X-ray analytical microscopy, magnetic resonance imaging and inductively coupled plasma–atomic emission spectroscopy. According dynamic laser scattering analysis, the actual particle size of obtained metal oxide was similar to that of metal particles. The estimated diameters were ca. one micrometer. After administration through the tail vein of the mice, metal particles quickly reached some organs. The distribution ratio reached a constant value and was then maintained. On the other hand, the metal oxide particles were first localized in the spleen and lung. The concentration in the lung was decreased with post-injection time. This result suggested that the particles were temporally trapped in the lung then removed to other organs. The behaviors between metal and metal oxide were quite different even when those particles had a similar actual particle size. Therefore, the distribution behavior of particles depended on the chemical species.