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Capability of Au nano-rhombic dodecahedra in a label-free colorimetric assay: application in the determination of S2− and Hg2+
Analyst ( IF 3.6 ) Pub Date : 2022-07-04 , DOI: 10.1039/d2an00852a
Yali Shi 1 , Qianyuan Chen 1 , Yuejun Liu 2 , Guoqing Wang 1, 3
Affiliation  

Anisotropic nanoparticles possess high sensitivity to the environmental refractive index that is strongly dependent on their active facets. As a polyhedron exclusively enclosed by active facets, Au nano-rhombic dodecahedra (AuNRDs) with multiple tips and edges have been less explored with respect to their capability in surface plasmon resonance (SPR) sensing. Here, we report on the use of AuNRDs in the colorimetric detection of S2− and Hg2+. Upon Ag coating, the AuNRDs can probe S2− with high sensitivity and selectivity due to the chemical transformation of Ag into Ag2S. Furthermore, Hg2+ can be detected by the SPR of the AuNRDs based on the formation of HgS from the Ag2S shell on the AuNRDs. These changes in the morphology and composition of the AuNRDs have been confirmed by electron microscopy and elemental mapping. The promising colorimetric response of Ag-coated AuNRDs to S2− is visible through the naked eye and the change in the SPR of the AuNRDs shifted linearly with an increasing concentration of S2− in the range of 0.5–15 μM, with a detection limit of 0.26 μM. The change in the SPR of the Ag2S-coated AuNRDs also indicates a dependence on the concentration of Hg2+ in the range from 0 to 100 μM, with a detection limit of 38 nM. The limits of detection are lower or close to the maximum allowable levels of S2− and Hg2+ for drinking water defined by national or international administrations. These seminal results unveil new opportunities for the AuNRDs and other anisotropic nanostructures with active facets in SPR-based sensing applications.

中文翻译:

Au 纳米菱形十二面体在无标记比色测定中的能力:在 S2- 和 Hg2+ 测定中的应用

各向异性纳米粒子对环境折射率具有高度敏感性,这强烈依赖于它们的活性面。作为仅由活性面包围的多面体,具有多个尖端和边缘的金纳米菱形十二面体 (AuNRD) 在表面等离子体共振 (SPR) 传感方面的研究较少。在这里,我们报告了 AuNRD 在 S 2−和 Hg 2+的比色检测中的使用。在 Ag 涂层上,由于 Ag 化学转化为 Ag 2 S,AuNRDs 可以以高灵敏度和选择性探测 S 2- 。此外,基于 HgS 的形成,AuNRDs 的 SPR 可以检测Hg 2+2AuNRD 上的 S 外壳。AuNRDs 的形态和组成的这些变化已通过电子显微镜和元素映射得到证实。通过肉眼可以看到Ag 涂层的 AuNRDs 对 S 2-的有希望的比色响应,并且随着 S 2-浓度在 0.5-15 μM 范围内的增加,AuNRDs 的 SPR 变化呈线性变化,检测到限制为 0.26 μM。Ag 2 S 包覆的AuNRDs 的SPR 变化也表明在0 至100 μM 范围内对Hg 2+浓度的依赖性,检测限为38 nM。检测限低于或接近 S 2−和 Hg 2+的最大允许水平用于由国家或国际管理部门定义的饮用水。这些开创性的结果为 AuNRD 和其他具有活性面的各向异性纳米结构在基于 SPR 的传感应用中提供了新的机会。
更新日期:2022-07-04
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