Toxicity Mechanism Of Engineered Copper Oxide Nanoparticles To Tabacco BY2Cells

The rapid development of nanotechnology has promoted the production andapplication of nano products. This inevitably leads the engineered nanoparticles（ENPs） to releasing to the environment. They are able to interact with living beings inthe environment and bring potential harmful impact on human beinggs and ecosystem.Many papers have reported the toxicity of ENPs on animals, plants, microorganisms,algae and animal cells currently, however, few studies have reported on the plants.Plants, the primary producers, play a vital role in keeping stable of the ecosystems.We select the hela cells of plantae—tobacco BY2cells—as testing cells to investigatethe toxicity mechanism of CuO ENPs to tabacco BY2suspention cells and the mainresults are summarized as follows:1. Toxicity of different concentration of CuO ENPs totabacco BY2cells wasinvestigated in this study. Viability of cells depended to the concentrations ofCuO ENPs. CuO ENPs (>4mg·L^-1) had significant toxicity to tabacco BY2cellsand the24h IC50was12mg·L^-1. Therefore, BY2cells exposed to12mg·L^-1CuO ENPs for24h was chosen for the following experiments of toxicitymechanism.2. CuO BPs (12mg·L^-1) and Cu²⁺(0.8mg·L^-1) showed much lower toxicity thanCuO ENPs (12mg·L^-1) treatment. The cytotoxicity caused mainly due to the sizerather than ion released from (12mg·L^-1CuO ENPs).3. Comparing the uptake content of CuO ENPs between the cells with and withoutwortmannin pretreatment, endocytosis was confirmed to be one of the importantpathways of CuO ENPs uptake. TEM observed that CuO ENPs were adsorptedto the cell wall, and the fiber layer of the cell wall became loose and disorder.Then CuO ENPs were disintegrated to CuO at size of3-10nm. CuO particles oraggregates crossed the cell wall and entered the cell which mainly distributed in the cytoplasm, mitochondria and vacuoles.4. Intracellular CuO ENPs generate ROS and accreted the content of H₂O₂, OH,which resulted in oxidative stress. The activity of CAT and SOD was increasedby feedback regulation. Hence it strengthened the capacity of scavengingexcessive free radical and enhanced the antioxidant capacity of the cell5. CuO ENPs caused leakage of lactate dehydrogenase and lipid peroxidation ofcell, which destructed the stability of the cell membrane. Comparing the ROS inthe cells with and without the inhibitors of mitochondrial electron transport chainpretreatment, we found that CuO ENPs could interrupt the electronic passingfrom NADH to ubiquinone or from ubiquinone to cytochrome, thus, generatedthe reactive oxygen species caused by the leakage of electron.