Time-dependence and visualization of TiO2 and Pt particle biodistribution in mice.

Micro- and nano-sized materials have received much attention regarding their biocompatibility and toxicity. To understand the influence of such materials on animals, it is very important to determine their internal distribution behavior. In this study, the biodistributions of Pt and TiO2 micro- and nano-sized particles in mice were estimated and visualized by X-ray scanning analytical microscopy and inductively coupled plasma-atomic emission spectroscopy. We also determined the effect of particle size, difference between metal and oxide, and time dependence for the distributions, because the biodistribution depends upon both the chemical character of materials and the size of particles. The results of the present study indicated that the difference in chemical character had a greater effect than did particle size. We predict that X-ray scanning analytical microscopy will be a useful method for studying biodistribution of micro- and nano-sized particles, because this method requires no labeling or treatment of the target particles.