Da Qiang, Gu Yuanyuan, Peng Xiafeng, Zhang Liying, Du Shuhu
School of Pharmacy, Nanjing Medical University, Nanjing, 211166, Jiangsu, China.
School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166, Jiangsu, China.
Mikrochim Acta. 2018 Jul 4;185(7):357. doi: 10.1007/s00604-018-2899-y.
A colorimetric and visual method is described for the determination of mercury(II) ion. A gel consisting of agar-stabilized silver-coated gold nanoparticles (Au@Ag NPs) was prepared. The reaction with dithiothreitol (DTT) via thiol-Ag chemistry results in an orange to purple color change of the gel. However, in the presence of Hg(II), the reaction of DTT with the silver shells is suppressed due to the strong thiophilicity of Hg(II). The color of the gel changes from purple to red to orange in the presence of increasing concentrations of Hg(II). The Au@Ag NPs therefore are a viable optical probe for Hg(II) which can be detected in concentration as low as 78 nM via dual-wavelength ratiometric absorbance (A/A), and at 1 μM levels with bare eyes. The use of agar as a support is mandatory to prevent the aggregation of the NPs and also improves selectivity. The method was applied to the analysis of spiked samples, and recoveries ranged between 96.3 and 104%. The assay is easy, inexpensive, and in our perception represents an attractive tool for on-site visual detection of Hg(II). Graphical abstract Schematic of the assay. With increasing concentrations of Hg(II), the oxidative etching of silver shells caused by dithiothreitol (DTT) is gradually inhibited, and the color of agar-stabilized Au@Ag NP gel varies from purple to red, and finally to orange. This can be used for visual detection of Hg(II).
描述了一种用于测定汞（II）离子的比色和可视化方法。制备了一种由琼脂稳定的包覆银的金纳米颗粒（Au@Ag NPs）组成的凝胶。通过硫醇-银化学与二硫苏糖醇（DTT）反应会导致凝胶从橙色变为紫色。然而，在汞（II）存在下，由于汞（II）具有很强的亲硫性，DTT与银壳的反应受到抑制。在汞（II）浓度增加时，凝胶颜色从紫色变为红色再变为橙色。因此，Au@Ag NPs是一种可行的汞（II）光学探针，通过双波长比率吸光度（A/A）可检测低至78 nM浓度的汞（II），肉眼可检测1 μM水平的汞（II）。使用琼脂作为载体对于防止纳米颗粒聚集是必不可少的，并且还提高了选择性。该方法应用于加标样品分析，回收率在96.3%至104%之间。该测定方法简便、廉价，在我们看来是一种用于现场可视化检测汞（II）的有吸引力的工具。图形摘要 测定示意图。随着汞（II）浓度增加，二硫苏糖醇（DTT）引起的银壳氧化蚀刻逐渐受到抑制，琼脂稳定的Au@Ag NP凝胶颜色从紫色变为红色，最终变为橙色。这可用于汞（II）的可视化检测。
