State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Jilin, China.
ACS Appl Mater Interfaces. 2011 Aug;3(8):2928-31. doi: 10.1021/am2007678. Epub 2011 Jul 28.
As an extension of our previous work, which described the unique ability of the core/shell Cu@Au nanoparticle (NP) to selectively recognize iodide, (1) herein, we wish to report the development of an alternatively sensitive and selective colorimetric detection for sulfide anion and cysteine based upon the Cu@Au NP by a competition avenue. In the absence of sulfide anion or cysteine, iodide can induce an appreciable color change of the Cu@Au NP solution from purple to red by transforming the clusters of NP to single, nearly spherical, and larger ones. However, the transformation is severely interfered by the presence of sulfide or cysteine because of a higher binding strength of the S-Au bond than the I-Au one. As a result, the clear purple-to-red color change induced by iodide is affected as a correlation with the concentration of sulfide or cysteine. By taking advantage of this fact, we can detect a concentration of 3 μM for sulfide and 0.4 μM for cysteine with the naked eye or 0.3 μM (10 ppb) for sulfide and 50 nM (6 ppb) for cysteine aided by a UV/vis spectrometer. Given the detrimental effect of hydrogen sulfide and the biological importance of cysteine, the assay may become useful in the environment monitoring, water quality inspection and biomedical diagnosis as well.
作为我们之前工作的延伸，该工作描述了核/壳 Cu@Au 纳米粒子 (NP) 选择性识别碘化物的独特能力，(1) 在此，我们希望基于 Cu@Au NP 通过竞争途径报告开发一种替代的对硫化物阴离子和半胱氨酸具有高灵敏度和选择性的比色检测方法。在没有硫化物阴离子或半胱氨酸的情况下，碘化物可以通过将 NP 簇转化为单个、几乎球形和更大的 NP 来诱导 Cu@Au NP 溶液从紫色到红色的明显颜色变化。然而，由于 S-Au 键的结合强度高于 I-Au 键，因此硫化物或半胱氨酸的存在严重干扰了这种转化。因此，碘化物诱导的明显的紫色到红色颜色变化会受到硫化物或半胱氨酸浓度的影响。利用这一事实，我们可以用肉眼检测到 3 μM 的硫化物和 0.4 μM 的半胱氨酸，或借助紫外/可见分光光度计检测到 0.3 μM（10 ppb）的硫化物和 50 nM（6 ppb）的半胱氨酸。鉴于硫化氢的有害影响和半胱氨酸的生物学重要性，该测定方法可能在环境监测、水质检查和生物医学诊断中变得有用。
