Takamitsu Miyayama    Department   School of Medicine, School of Medicine    Position   Assistant Professor
Language	English
Title	Cellular distribution of silver nanoparticles and behavior of metallothionein in human bronchial epithelial cells
Conference	6th International Symposium on Nanotechnology, Occupational and Environmental Health
Promoters	6th International Symposium on Nanotechnology, Occupational and Environmental Health Organizing Committee
Conference Type	International society and overseas society
Presentation Type	Poster notice
Lecture Type	General
Publisher and common publisher	◎MIYAYAMA Takamitsu, ARAI Yuta, SUZUKI Noriyuki, HIRANO Seishiro
Date	2013/10/28
Venue (city and name of the country)	Nagoya, Japan
Society abstract	Abstract:6th International Symposium on Nanotechnology, Occupational and Environmental Health 86
Summary	Silver nanoparticles (AgNPs) are commercially used as antibacterial reagents. However, the mechanisms underlying Ag toxicity in mammals are not fully understood. In the present study, we assessed distribution and toxicity of AgNPs and silver nitrite (AgNO3) in human bronchial epithelial cell (BEAS-2B) focusing on behavior of metallothionein (MT). The cells were exposed to 0 - 500 μg Ag/mL AgNPs or 0 - 100 μmol/L AgNO3 for up to 24 h. The cytotoxicity was assayed by a modified MTT method. The cellular concentration and distribution of Ag were evaluated by ICP-MS and laser scanning microscopy, respectively. Distribution of Ag to MT and other proteins was determined using HPLC-ICP-MS. Ag was distributed to MT in AgNPs exposed cells in a time-dependent manner, suggesting that soluble As was released from AgNPs. On the other hand, cellular Ag concentration and Ag-bound MT (Ag-MT) were sharply increased up to 3 h and then decreased in AgNO3-exposed cells. The agglomerated AgNPs were found in lysosomes at 24 h after exposure. ROS generation occurred in the mitochondria following treatment with AgNO3. The effect of Ag on respiration in rat liver mitochondria was assessed by measuring O2 consumption. Exposure to AgNO3 resulted in a dose-dependent decrease in mitochondrial oxygen consumption as AgNO3 inhibited the electron transport chain enzymes associated with complexes I-IV in mitochondria. ROS production appeared to cause relocation of Ag-MT to mitochondria, which evoked inhibition of electron transport chain. These results suggest that the difference in cytotoxicity between AgNP and AgNO3 is probably due to the stability of Ag-MT and degradation of Ag-MT may lead to cell damage.
URL for researchmap	http://square.umin.ac.jp/nanoeh6/index.html