Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic.
Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic; Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic.
Talanta. 2017 Oct 1;173:28-35. doi: 10.1016/j.talanta.2017.05.055. Epub 2017 May 22.
The manuscript presents a procedure for optimal sample preparation and the mapping of the spatial distribution of metal ions and nanoparticles in plant roots using laser-induced breakdown spectroscopy (LIBS) in a double-pulse configuration (DP LIBS) in orthogonal reheating mode. Two Nd:YAG lasers were used; the first one was an ablation laser (UP-266 MACRO, New Wave, USA) with a wavelength of 266nm, and the second one (Brilliant, Quantel, France), with a fundamental wavelength of 1064nm, was used to reheat the microplasma. Seedlings of Vicia faba were cultivated for 7 days in CuSO or AgNO solutions with a concentration of 10µmoll or in a solution of silver nanoparticles (AgNPs) with a concentration of 10µmoll of total Ag, and in distilled water as a control. The total contents of the examined metals in the roots after sample mineralization as well as changes in the concentrations of the metals in the cultivation solutions were monitored by ICP-OES. Root samples embedded in the TissueTek medium and cut into 40µm thick cross sections using the Cryo-Cut Microtome proved to be best suited for an accurate LIBS analysis with a 50µm spatial resolution. 2D raster maps of elemental distribution were created for the emission lines of Cu(I) at 324.754nm and Ag(I) at 328.068nm. The limits of detection of DP LIBS for the root cross sections were estimated to be 4pg for Cu, 18pg for Ag, and 3pg for AgNPs. The results of Ag spatial distribution mapping indicated that unlike Ag ions, AgNPs do not penetrate into the inner tissues of Vicia faba roots but stay in their outermost layers. The content of Ag in roots cultivated in the AgNP solution was one order of magnitude lower compared to roots cultivated in the metal ion solutions. The significantly smaller concentration of Ag in root tissues cultivated in the AgNP solution also supports the conclusion that the absorption and uptake of AgNPs by roots of Vicia faba is very slow. LIBS mapping of root sections represents a fast analytical method with sufficient precision and spatial resolution that can provide very important information for researchers, particularly in the fields of plant science and ecotoxicology.
本文提出了一种使用激光诱导击穿光谱（LIBS）在双脉冲配置（DP LIBS）中以正交再加热模式对植物根系中的金属离子和纳米粒子的空间分布进行最佳样品制备和映射的方法。使用了两个 Nd:YAG 激光器；第一个是波长为 266nm 的消融激光（UP-266 MACRO，New Wave，美国），第二个是波长为 1064nm 的基本波长的再加热激光（Brilliant，Quantel，法国）。将蚕豆幼苗在浓度为 10µmol 的 CuSO 或 AgNO 溶液或浓度为 10µmol 总 Ag 的银纳米粒子（AgNPs）溶液中培养 7 天，并以蒸馏水作为对照。通过 ICP-OES 监测样品矿化后根系中检查金属的总量以及培养溶液中金属浓度的变化。通过将嵌入 TissueTek 培养基中的根样本切成 40µm 厚的横截面，然后使用 Cryo-Cut 切片机，证明最适合使用 50µm 空间分辨率进行准确的 LIBS 分析。为发射线创建了 Cu(I)在 324.754nm 和 Ag(I)在 328.068nm 的元素分布 2D 光栅图。估计 DP LIBS 对根横截面的检测限分别为 Cu 为 4pg，Ag 为 18pg，AgNPs 为 3pg。Ag 空间分布映射的结果表明，与 Ag 离子不同，AgNPs 不会渗透到蚕豆根系的内部组织中，而是停留在其最外层。与在金属离子溶液中培养的根相比，在 AgNP 溶液中培养的根中的 Ag 含量低一个数量级。在 AgNP 溶液中培养的根组织中 Ag 的浓度明显较小也支持 AgNPs 被蚕豆根系吸收和摄取非常缓慢的结论。根节段的 LIBS 图谱代表了一种具有足够精度和空间分辨率的快速分析方法，可以为研究人员提供非常重要的信息，特别是在植物科学和生态毒理学领域。
