State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
PLoS One. 2011;6(9):e24406. doi: 10.1371/journal.pone.0024406. Epub 2011 Sep 29.
Quantum dots (QDs), as unique nanoparticle probes, have been used in in vivo fluorescence imaging such as cancers. Due to the novel characteristics in fluorescence, QDs represent a family of promising substances to be used in experimental and clinical imaging. Thus far, the toxicity and harmful health effects from exposure (including environmental exposure) to QDs are not recognized, but are largely concerned by the public. To assess the biological effects of QDs, we established a mouse model of acute and chronic exposure to QDs. Results from the present study suggested that QD particles could readily spread into various organs, and liver was the major organ for QD accumulation in mice from both the acute and chronic exposure. QDs caused significant impairments to livers from mice with both acute and chronic QD exposure as reflected by morphological alternation to the hepatic lobules and increased oxidative stress. Moreover, QDs remarkably induced the production of intracellular reactive oxygen species (ROS) along with cytotoxicity, as characterized by a significant increase of the malondialdehyde (MDA) level within hepatocytes. However, the increase of the MDA level in response to QD treatment could be partially blunted by the pre-treatment of cells with beta-mercaptoethanol (β-ME). These data suggested ROS played a crucial role in causing oxidative stress-associated cellular damage from QD exposure; nevertheless other unidentified mediators might also be involved in QD-mediated cellular impairments. Importantly, we demonstrated that the hepatoxicity caused by QDs in vivo and in vitro was much greater than that induced by cadmium ions at a similar or even a higher dose. Taken together, the mechanism underlying QD-mediated biological influences might derive from the toxicity of QD particles themselves, and from free cadmium ions liberated from QDs as well.
量子点（QD）作为独特的纳米颗粒探针，已被用于活体荧光成像，例如癌症。由于在荧光方面具有新颖的特性，QD 代表了一类有前途的物质，可用于实验和临床成像。到目前为止，尚未认识到暴露（包括环境暴露）于 QD 产生的毒性和对健康的有害影响，但公众对此高度关注。为了评估 QD 的生物学效应，我们建立了急性和慢性暴露于 QD 的小鼠模型。本研究的结果表明，QD 颗粒很容易扩散到各种器官中，并且在急性和慢性 QD 暴露的小鼠中，肝脏是 QD 积累的主要器官。QD 对急性和慢性 QD 暴露的小鼠肝脏造成了明显的损害，表现为肝小叶的形态改变和氧化应激增加。此外，QD 可显著诱导细胞内活性氧（ROS）的产生以及细胞毒性，其特征是肝细胞内丙二醛（MDA）水平显著升高。然而，用β-巯基乙醇（β-ME）预处理细胞可部分减轻 MDA 水平因 QD 处理而增加的现象。这些数据表明 ROS 在引起与 QD 暴露相关的氧化应激相关的细胞损伤中起关键作用；然而，其他未识别的介质也可能参与 QD 介导的细胞损伤。重要的是，我们证明了 QD 在体内和体外引起的肝毒性比相同甚至更高剂量的镉离子引起的肝毒性要大得多。总之，QD 介导的生物学影响的机制可能源于 QD 颗粒本身的毒性以及从 QD 释放的游离镉离子的毒性。
