State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu Province, 210046, China.
Environ Sci Technol. 2013 Sep 17;47(18):10601-10. doi: 10.1021/es4017188. Epub 2013 Aug 27.
The bioaccumulation kinetics of thioglycolic acid stabilized CdTe quantum dots (TGA-CdTe-QDs) in a freshwater alga Ochromonas danica was comprehensively investigated. Their photoluminescence (PL) was determined by flow cytometry. Its cellular intensity increased hyperbolically with exposure time suggesting real internalization of TGA-CdTe-QDs. This hypothesis was evidenced by the nanoparticle uptake experiment with heat-killed or cold-treated cells and by their localization in the vacuoles. TGA-CdTe-QD accumulation could further be well simulated by a biokinetic model used previously for conventional pollutants. Moreover, macropinocytosis was the main route for their internalization. As limited by their diffusion from the bulk medium to the cell surface, TGA-CdTe-QD uptake rate increased proportionally with their ambient concentration. Quick elimination in the PL of cellular TGA-CdTe-QDs was also observed. Such diminishment resulted mainly from their surface modification by vacuolar biomolecules, considering that these nanoparticles remained mostly undissolved and their expulsion out of the cells was slow. Despite the significant uptake of TGA-CdTe-QDs, they had no direct acute effects on O. danica. Overall, the above research shed new light on nanoparticle bioaccumulation study and would further improve our understanding about their environmental behavior, effects and fate.
本文综合研究了巯基乙酸稳定的碲化镉量子点（TGA-CdTe-QDs）在淡水藻类眼虫中的生物积累动力学。采用流式细胞术测定其光致发光（PL）。其细胞强度随暴露时间呈超抛物线增长，表明 TGA-CdTe-QDs 确实被内化。这一假设通过对热灭活或冷处理细胞的纳米颗粒摄取实验以及它们在液泡中的定位得到了证实。TGA-CdTe-QD 的积累可以通过先前用于传统污染物的生物动力学模型进行很好的模拟。此外，巨胞饮作用是其内化的主要途径。由于 TGA-CdTe-QD 从主体介质扩散到细胞表面受到限制，其摄取速率与环境浓度成正比增加。在细胞 TGA-CdTe-QDs 的 PL 中也观察到快速消除。由于这些纳米颗粒大部分未溶解且排出细胞的速度较慢，因此这种减少主要归因于液泡生物分子对其表面的修饰。尽管 TGA-CdTe-QDs 被大量吸收，但它们对眼虫没有直接的急性影响。总的来说，上述研究为纳米颗粒生物积累研究提供了新的视角，并将进一步提高我们对其环境行为、影响和归宿的认识。
