Plant Cell Biotechnology Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal.
BMC Biotechnol. 2013 Dec 20;13:111. doi: 10.1186/1472-6750-13-111.
Nanoparticles appear to be promising devices for application in the agriculture and food industries, but information regarding the response of plants to contact with nano-devices is scarce. Toxic effects may be imposed depending on the type and concentration of nanoparticle as well as time of exposure. A number of mechanisms may underlie the ability of nanoparticles to cause genotoxicity, besides the activation of ROS scavenging mechanisms. In a previous study, we showed that plant cells accumulate 3-Mercaptopropanoic acid-CdSe/ZnS quantum dots (MPA-CdSe/ZnS QD) in their cytosol and nucleus and increased production of ROS in a dose dependent manner when exposed to QD and that a concentration of 10 nM should be cyto-compatible.
When Medicago sativa cells were exposed to 10, 50 and 100 nM MPA-CdSe/ZnS QD a correspondent increase in the activity of Superoxide dismutase, Catalase and Glutathione reductase was registered. Different versions of the COMET assay were used to assess the genotoxicity of MPA-CdSe/ZnS QD. The number of DNA single and double strand breaks increased with increasing concentrations of MPA-CdSe/ZnS QD. At the highest concentrations, tested purine bases were more oxidized than the pyrimidine ones. The transcription of the DNA repair enzymes Formamidopyrimidine DNA glycosylase, Tyrosyl-DNA phosphodiesterase I and DNA Topoisomerase I was up-regulated in the presence of increasing concentrations of MPA-CdSe/ZnS QD.
Concentrations as low as 10 nM MPA-CdSe/ZnS Quantum Dots are cytotoxic and genotoxic to plant cells, although not lethal. This sets a limit for the concentrations to be used when practical applications using nanodevices of this type on plants are being considered. This work describes for the first time the genotoxic effect of Quantum Dots in plant cells and demonstrates that both the DNA repair genes (Tdp1β, Top1β and Fpg) and the ROS scavenging mechanisms are activated when MPA-CdSe/ZnS QD contact M. sativa cells.
纳米颗粒似乎是农业和食品工业应用的有前途的工具，但有关植物与纳米器件接触的反应的信息却很少。毒性效应可能取决于纳米颗粒的类型和浓度以及暴露时间。除了激活 ROS 清除机制外，许多机制可能使纳米颗粒具有遗传毒性。在之前的研究中，我们表明植物细胞在细胞质和核中积累 3-巯基丙酸-CdSe/ZnS 量子点（MPA-CdSe/ZnS QD），并且当暴露于 QD 时，以剂量依赖的方式增加 ROS 的产生，并且 10 nM 的浓度应该是细胞相容的。
当 Medicago sativa 细胞暴露于 10、50 和 100 nM MPA-CdSe/ZnS QD 时，超氧化物歧化酶、过氧化氢酶和谷胱甘肽还原酶的活性相应增加。使用不同版本的 COMET 测定法评估 MPA-CdSe/ZnS QD 的遗传毒性。随着 MPA-CdSe/ZnS QD 浓度的增加，DNA 单链和双链断裂的数量增加。在最高浓度下，测试的嘌呤碱基比嘧啶碱基更容易氧化。在 MPA-CdSe/ZnS QD 浓度增加的情况下，DNA 修复酶 Formamidopyrimidine DNA 糖基化酶、酪氨酸-DNA 磷酸二酯酶 I 和 DNA 拓扑异构酶 I 的转录被上调。
尽管浓度低至 10 nM 的 MPA-CdSe/ZnS 量子点对植物细胞具有细胞毒性和遗传毒性，但不会致死。这为考虑在植物上使用此类纳米器件进行实际应用时要使用的浓度设定了限制。这项工作首次描述了量子点对植物细胞的遗传毒性作用，并表明当 MPA-CdSe/ZnS QD 接触 M. sativa 细胞时，不仅激活了 DNA 修复基因（Tdp1β、Top1β 和 Fpg），还激活了 ROS 清除机制。
