Biodistribution of gold nanoparticles in mice and investigation of their possible translocation by nerve uptake around the alveolus

Abstract

The effect of nanoparticles in the environment on our health is a cause of concern. The greatest concern with respect to the biological effect of nanoparticles is that they remain in the body and invade tissues, overcoming the protective mechanisms of the body. It is generally believed that nanoparticles invading a living body move into the blood and are carried by the bloodstream to all organs. However, some studies have shown that the inhaled nanoparticles directly translocate to the central nervous system by nerve uptake. Here quantification of the amount of migration of nanoparticles to organs in short time spans (1, 3, and 6 hr) was attempted by animal experiments. Furthermore, the possibility of migration of nanoparticles through the nerves that project around the alveolus, including the nodose ganglion and dorsal root ganglion (DRG), was investigated. Gold (Au) nanoparticles (15 nm) were administered to mice by intratracheal instillation and tail vein injection. After tail vein injection, most nanoparticles were distributed in the liver. After intratracheal instillation, approximately 80% of detected nanoparticles remained in the lungs at 1 hr and were believed to be translocated to digestive organs, including the stomach and intestine, at 3 and 6 hr. With respect to quantification in ganglia, the levels in most samples were lower than the limit of quantification of inductively coupled plasma mass spectrometry (ICP-MS). However, Au nanoparticles were detected in DRG in only some samples of intratracheal instillation. Therefore, this suggests the possibility of translocation of nanoparticles to DRG via nerves.