Wang Bing, Zhang Yuying, Mao Zhengwei, Yu Dahai, Gao Changyou
J Nanosci Nanotechnol. 2014 Aug;14(8):5688-96. doi: 10.1166/jnn.2014.8876.
Although the ZnO nanoparticles (NPs) have been widely used in research and industry, their health risks are only concerned very recently. In this paper, attention is paid to elucidate the toxic effects and intrinsic mechanism of ZnO NPs to RAW 246.7 macrophage cells. The ZnO NPs from industry additives had a diameter of ~37 nm in a dry state and aggregated to submicron size in cell culture medium with slightly negative surface charge. Influences of ZnO NPs on cell toxicity and functions were then studied in terms of cell viability, mitochondrial membrane potential (MMP), total and released lactate dehydrogenase (LDH) activity, intracellular level of reactive oxygen species (ROS) and Zn2+ concentration. The ZnO NPs induced elevation of intracellular Zn2+ concentration, leading to the over generation of intracellular ROS, leakage of plasma membrane, dysfunction of mitochondria, and cell death. The solubility of ZnO NPs was found largely enhanced in acidic environment (pH 5.5), compared to physiological condition (pH 7.2). Inhibition of cell uptake of ZnO NPs would largely reduce the cytotoxicity. These results demonstrate that the cell uptake, intracellular dissolution and thereafter release of Zn2+ are the intrinsic reasons for the high toxicity of ZnO NPs.
尽管氧化锌纳米颗粒（NPs）已在研究和工业中广泛使用，但其健康风险直到最近才受到关注。本文致力于阐明氧化锌纳米颗粒对RAW 246.7巨噬细胞的毒性作用及其内在机制。工业添加剂中的氧化锌纳米颗粒在干燥状态下直径约为37 nm，在细胞培养基中聚集到亚微米大小，表面电荷略带负电。然后从细胞活力、线粒体膜电位（MMP）、总乳酸脱氢酶（LDH）活性和释放的LDH活性、细胞内活性氧（ROS）水平以及Zn2+浓度等方面研究了氧化锌纳米颗粒对细胞毒性和功能的影响。氧化锌纳米颗粒导致细胞内Zn2+浓度升高，进而导致细胞内ROS过度生成、质膜泄漏、线粒体功能障碍和细胞死亡。与生理条件（pH 7.2）相比，发现氧化锌纳米颗粒在酸性环境（pH 5.5）中的溶解度大大提高。抑制细胞对氧化锌纳米颗粒的摄取将大大降低细胞毒性。这些结果表明，细胞摄取、细胞内溶解以及随后Zn2+的释放是氧化锌纳米颗粒高毒性的内在原因。
