Laboratory of Molecular Genetics, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia.
Toxicology. 2010 Mar 10;269(2-3):182-9. doi: 10.1016/j.tox.2009.07.007. Epub 2009 Jul 19.
The toxic effects of nanoparticles (NPs) of ZnO and CuO to particle-ingesting model organism protozoa Tetrahymena thermophila were evaluated. Nano-ZnO was remarkably more toxic than nano-CuO (EC(50) values approximately 5mg metal/l versus 128mg metal/l). Toxic effect of CuO depended on particle size: nano-CuO was about 10-20 times more toxic than bulk CuO. However, when calculated on basis of bioavailable copper (quantified using recombinant Cu-sensor bacteria) the 4-h EC(50) values of nano- and bulk formulations were comparable (2.7 and 1.9mg bioavailable Cu/l, respectively), and statistically different from the EC(50) value of Cu(2+) (1.1mg/l). Differently from CuO particles, bulk and nanosized ZnO as well as Zn(2+) were of similar toxicity (4-h EC(50) values 3.7 and 3.9mg bioavailable Zn/l, respectively, and 4.9mg Zn(2+)/l). Thus, the toxic effect of both, CuO and ZnO (nano)particles to protozoa was caused by their solubilised fraction. The toxic effects of the copper compounds were not dependent on exposure time (4 and 24h), whereas the toxicity of zinc compounds was about 1.5 times lower after 24h of exposure than after 4h, probably due to adaptation. In summary, we recommend T. thermophila as a simple eukaryotic particle-ingesting model organism for the toxicity screening of NPs. For the high throughput testing we suggest to use the 4-h assay on microplates using ATP and/or propidium iodide for the evaluation of cell viability.
评价了 ZnO 和 CuO 纳米粒子（NPs）对吞噬模型生物原生动物四膜虫的毒性作用。纳米 ZnO 的毒性明显高于纳米 CuO（EC（50）值约为 5mg 金属/l 对 128mg 金属/l）。CuO 的毒性作用取决于颗粒尺寸：纳米 CuO 的毒性比块状 CuO 大约高 10-20 倍。然而，当根据生物可利用的铜（使用重组 Cu 传感器细菌定量）计算时，纳米和块状制剂的 4-h EC（50）值相当（分别为 2.7 和 1.9mg 生物可利用 Cu/l），且与 Cu（2+）的 EC（50）值（1.1mg/l）有统计学差异。与 CuO 颗粒不同，块状和纳米 ZnO 以及 Zn（2+）的毒性相似（4-h EC（50）值分别为 3.7 和 3.9mg 生物可利用 Zn/l，以及 4.9mg Zn（2+）/l）。因此，CuO 和 ZnO（纳米）颗粒对原生动物的毒性作用是由其溶解部分引起的。铜化合物的毒性作用不依赖于暴露时间（4 和 24h），而锌化合物的毒性在暴露 24h 后比暴露 4h 后约低 1.5 倍，可能是由于适应。总之，我们建议四膜虫作为一种简单的真核吞噬模型生物，用于 NPs 的毒性筛选。对于高通量测试，我们建议使用 4 小时微孔板测定法，使用 ATP 和/或碘化丙啶评估细胞活力。
