Nobuki Iwadera

Internal distribution of micro- / nano-sized inorganic particles and their cytocompatibility

Nano-sized materials have received much attention lately, both in terms of their multiple applications and their biocompatibility. From both viewpoints, understanding the biodistribution of administered nano-materials is very important. In this study, we succeeded in visualizing the biodistribution of administered nano-materials using a scanning X-ray analytical microscope and magnetic resonance imaging method. Quantitative observation was carried out by inductively coupled plasma – atomic emission spectroscopy. We observed that the administered nano-particles accumulated in the liver, lung and spleen of mice. To estimate their cytocompatibility, the nano-particles were exposed to human liver cells. The results suggested that the micro-/ nano- particles have good cytocompatibility, except for copper oxide nano-particles.

Cytocompatiblity of Ceramic Nanoparticles to Various Types of Cells

In this study, we investigated the cytocompatibility of ceramic nanoparticles on different types of cells. All ceramics nanoparticles investigated in this study except Copper oxide (CuO) exhibited good cytocompatibility and cell viability (90% or more) even at 20 ppm concentration. In contrast, CuO nanoparticles caused cell inflammation, and their effect depended on their particle size. Confocal fluorescence microscopy measurements indicated that some particles had penetrated into the cells. These results indicate that except CuO nanoparticles, all other ceramic nanoparticles reported herein exhibited excellent cytocompatibility even for lung epithelial cells.

Biocompatibility and Biodistribution of Several Nano-Sized Ceramics Particles

We succeeded in determination the biodistribution of several nano-sized particles administered to mice through the tail vein. After administration, these particles were observed in the lung, liver and spleen. The distribution behaviors depend upon not only chemical species but also the particles size. To estimate their cytocompatibility, these particles were exposed to osteoblastic cell at several concentrations. When the concentration reached at 10 ppm, their viability remained at 80% or more even nano-sized particle contained rare earth element. Only CuO particles indicated the viability decrease. The effect depended on the particle size. These results suggested that the chemical species played a dominant key in the biodistribution and biocompatibility of nanoparticles compared with the size-effect.

Influence of Micro-/Nano-Particles on Osteoblast-Like Cells: A Static and Time Lapse Observation

Cytotoxicity and cell behavior to micro / nanoparticles of TiO2 and CuO was evaluated using the viability measurement and time-lapse observation. After cultured, osteoblastic cells MC3T3-E1 were exposed to particles. After 24 hour exposure, their morphology was observed using a SEM and the viability was measured. Cells exposed to TiO2 indicated no or very low decrease of viability. The results were independent of the particle size. On the other hand, the viability of cells exposed to CuO decreased with the concentration, and showed the size dependence. The nanosized CuO indicated higher toxicity compared with micro-sized one. Dynamic behavior of cells exposed to nanoparticles, was succeeded to observe in a time-lapse method for 24 hours. The observation showed that the cells exposed to CuO became dead after forming a spherical shape. This is consistent with the image taken by SEM. Time-lapse observation made it possible to see the dynamic reaction process from cell contact to particles at first, the following cell activity response and finally to cell death, which revealed a considerably different morphology from the static cell observed after fixation by conventional method.