CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China, Beijing 100190, China.
Small. 2013 Jul 22;9(14):2440-51. doi: 10.1002/smll.201300861. Epub 2013 Jun 24.
Quantum dots (QDs) have attracted great attention because of their favorable optical properties and have been widely applied in biomedical fields. However, in recent years, there have been an increasing number of reports about the cytotoxicity of QDs, especially cadmium-containing QDs, which may release cadmium ions to induce cytotoxicity. Importantly, the chemical composition and surface modifications of cadmium-based QDs determine the amount of Cd(2+) released inside the cell. Thus, there is an urgent need for more systematic work to study the relationship between cytotoxicity and the surface properties of QDs. In this article, the cytotoxicity of seven cadmium-containing QDs with different constituent elements and surface chemistries are compared. The results show that the cytotoxicity of QDs is closely related to their constituent elements and surface properties: First, CdTe@ZnS core-shell QDs show much lower cytotoxicity than naked ones when they have similar surface modifications; second, the positively charged QDs are more toxic than the negatively charged ones. Moreover, both positively and negatively charged QDs without ZnS coatings lead to multipolar spindles, misaligned chromosomes, and G2/M checkpoint failures. Interestingly, although CdSe QDs with a PEG coating cause no apparent cytotoxicity in any of the cell lines studied, they can localize near the contractile ring during cytokinesis and then block contractile ring disassembly. The cellular effect of CdTe QDs comes not only from the release of cadmium ions but also the intracellular distribution of QD nanoparticles in cells and the associated nanoscale effects. It is also found that QD-caused cytokinesis failure is closely related to the decreased expression of Cyclin A and Cyclin B. Taken together, the above findings provide new insight into the dynamic fate of QDs during cell mitosis, and are important for understanding the intracellular effects of QDs on the mitotic spindle and chromosomes during cell division. Furthermore, this kind of cytotoxicity evaluation method should be applicable to studies of the biological effects and health impacts of other nanomaterials.
量子点 (QDs) 因其优异的光学性能而备受关注，并已广泛应用于生物医学领域。然而，近年来，越来越多的报道指出 QDs 具有细胞毒性，特别是含镉的 QDs，可能会释放镉离子从而诱导细胞毒性。重要的是，镉基 QDs 的化学成分和表面修饰决定了细胞内释放的 Cd(2+) 的量。因此，迫切需要更系统的工作来研究细胞毒性与 QDs 表面特性之间的关系。在本文中，比较了七种具有不同组成元素和表面化学性质的含镉 QDs 的细胞毒性。结果表明，QDs 的细胞毒性与其组成元素和表面性质密切相关：首先，当具有相似的表面修饰时，CdTe@ZnS 核壳 QDs 的细胞毒性明显低于裸露的 QDs；其次，带正电荷的 QDs 比带负电荷的 QDs 毒性更大。此外，没有 ZnS 涂层的带正电荷和带负电荷的 QDs 都会导致多极纺锤体、染色体排列不齐和 G2/M 检查点失效。有趣的是，尽管带有 PEG 涂层的 CdSe QDs 在研究的任何细胞系中都没有表现出明显的细胞毒性，但它们可以在胞质分裂过程中定位在收缩环附近，然后阻止收缩环的解体。CdTe QDs 的细胞效应不仅来自镉离子的释放，还来自细胞内 QD 纳米颗粒的分布和相关的纳米级效应。还发现 QD 引起的胞质分裂失败与 Cyclin A 和 Cyclin B 的表达减少密切相关。综上所述，这些发现为 QDs 在细胞有丝分裂过程中的动态命运提供了新的见解，对于理解 QDs 在细胞分裂过程中对有丝分裂纺锤体和染色体的细胞内效应非常重要。此外，这种细胞毒性评价方法应该适用于其他纳米材料的生物效应和健康影响的研究。
