Lai Lu, Jin Jian-Cheng, Xu Zi-Qiang, Mei Ping, Jiang Feng-Lei, Liu Yi
State Key Laboratory of Virology & Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecule Sciences, Wuhan University, Wuhan 430072, PR China; College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou 434023, PR China.
State Key Laboratory of Virology & Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecule Sciences, Wuhan University, Wuhan 430072, PR China.
Chemosphere. 2015 Sep;135:240-9. doi: 10.1016/j.chemosphere.2015.04.044. Epub 2015 May 15.
The toxicity of CdTe QDs with nearly identical maximum emission wavelength but modified with four different ligands (MPA, NAC, GSH and dBSA) to HEK293 and HeLa cells were investigated using flow cytometry, spectroscopic and microscopic methods. The results showed that the cytotoxicity of QDs increased in a dose- and time-dependent manner. No appreciable fraction of cells with sub-G1 DNA content, the loss of membrane integrity, and the swelling of nuclei clearly indicated that CdTe QDs could lead to necrotic cell death in HEK293 cells. JC-1 staining and TEM images confirmed that QDs induced MPT, which resulted in mitochondrial swelling, collapse of the membrane potential. MPT is an important step in QDs-induced necrosis. Moreover, QDs induced MPT through the elevation of ROS. The fluorimetric assay and theoretical analysis demonstrated ROS production has been associated with the internalization of QDs with cells. Due to large surface/volume ratios of QDs, when QDs added in the culture medium, serum proteins in the culture medium will be adsorbed on the surface of QDs. This adsorption of serum protein will change the surface properties and size, and then mediate the cellular uptake of QDs via the clathrin-mediated endocytic pathway. After entering into cells, the translocation of QDs in cells is usually via endosomal or lysosomal vesicles. The rapid degradation of QDs in lysosome and the lysosomal destabilization induce cell necrosis. This study provides a basis for understanding the cytotoxicity mechanism of CdTe QDs, and valuable information for safe use of QDs in the future.
使用流式细胞术、光谱学和显微镜方法，研究了四种不同配体（MPA、NAC、GSH和dBSA）修饰的、具有几乎相同最大发射波长的CdTe量子点对HEK293和HeLa细胞的毒性。结果表明，量子点的细胞毒性呈剂量和时间依赖性增加。没有明显比例的细胞具有亚G1期DNA含量、膜完整性丧失和细胞核肿胀，这清楚地表明CdTe量子点可导致HEK293细胞坏死性死亡。JC-1染色和透射电镜图像证实，量子点诱导了线粒体通透性转换（MPT），导致线粒体肿胀和膜电位崩溃。MPT是量子点诱导坏死的重要步骤。此外，量子点通过活性氧（ROS）的升高诱导MPT。荧光测定和理论分析表明，ROS的产生与量子点被细胞内化有关。由于量子点的表面积/体积比大，当量子点添加到培养基中时，培养基中的血清蛋白会吸附在量子点表面。血清蛋白的这种吸附会改变表面性质和尺寸，然后通过网格蛋白介导的内吞途径介导量子点的细胞摄取。进入细胞后，量子点在细胞内的转运通常通过内体或溶酶体囊泡进行。量子点在溶酶体中的快速降解和溶酶体的不稳定诱导细胞坏死。本研究为理解CdTe量子点的细胞毒性机制提供了依据，并为未来安全使用量子点提供了有价值的信息。
