修饰化量子点CdTe QDs对人体细胞的毒性评价研究

In this project,human colon cancer cells Caco-2 utilized to study low dose core-shell CdTe/ZnS quantum dots (CdTe/ZnS QDs), which were modified by three different coating including cysteamine, mercaptosuccinic acid and poly ethylene glycol, induced DNA damage, apoptosis, secretion of cytokines and oxidative stress mechanisms in the specific biological microenvironment. To examine modulation of enteric epithelial barrier function of Caco-2 monolayer cell by modified CdTe/ZnS QDs, including the transmembrane flux of monolayer cell and the expression of tight junction associate protein. This project discuss the kinetic mechanism of endocytosis of Caco-2 cell, intracellular transport targets and possible organelles pressure. Using the benchmark dose, combined with the characteristic parameter of CdTe/ZnS QDs to evaluate their dose-response relationship and to study the connection between cytotoxicity with the composition of CdTe/ZnS QDs. The purpose of this project is to explore a new health risk evaluate method of modified QDs in vitro. To provide a scientific basis for further cytotoxicity studies of modified CdTe/ZnS QDs and risk assessment of human health.

本项目拟以巯基乙胺、巯基丁二酸和聚乙二醇修饰的核壳结构CdTe/ZnS量子点（CdTe/ZnS QDs）作为研究对象，选用人结肠癌细胞Caco-2为模式生物，研究特定生物微环境中，低剂量修饰化QDs暴露对Caco-2细胞DNA损伤、细胞凋亡、细胞因子分泌以及氧化应激机制的影响。建立Caco-2细胞单层细胞模型，测定修饰化CdTe/ZnS QDs暴露对细胞单层的跨膜通量与细胞紧密连接结构等肠上皮屏障功能的影响。探讨Caco-2细胞对修饰化CdTe/ZnS QDs内吞的动力学机制、细胞内转运靶点及其可能引起的细胞器压力。采用基准剂量法，结合特性表征参数，对其剂量-反应关系加以评估，并获取细胞毒性与QDs组成结构之间的联系规律，探索一条应用体外分析方法评价修饰化QDs健康风险的新途径。为进一步的修饰化CdTe/ZnS QDs细胞毒性研究和人体健康风险评价提供科学依据。

选用了巯基乙胺修饰化的镉量子点（TGA-modified CdTe/ZnS)、氮量子点（Nitrogen-rich quantum dots）和铜胭硫量子点（CuInS2/ZnS）进行体外毒性研究。具体地讲，将三种不同浓度的量子点在Caco-2 细胞中孵育各种时间，检测各种细胞毒性指标、相关细胞因子以及凋亡指标。几种量子点对Caco-2细胞增殖均具有不同程度的抑制作用并随时间延长而增强。磷酸化半胱天冬酶-3、半胱天冬酶-9、细胞色素C、MTP的表达呈浓度依赖性增加，表明这些量子点可能促进线粒体凋亡途径。纳米细胞毒性研究结果为这些纳米材料在不同领域中的应用提供了佐证参考，探索一条应用体外分析方法评价修饰化QDs健康风险的新途径。为进一步的修饰化CdTe QDs细胞毒性研究和人体健康风险评价提供科学依据。