State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Jilin, China.
ACS Appl Mater Interfaces. 2011 Oct;3(10):4092-100. doi: 10.1021/am200972g. Epub 2011 Oct 6.
Recognition and sensing of anions in aqueous media have been of considerable interest while remaining a challenging task up to date. In this document, we wish to present a simple yet sensitive method to detect inorganic anions by colorimetry based on the citrate-stabilized core/shell Cu@Ag nanoparticle (NP). It was found that the NP could discriminate some specific anions (Cl(-), Br(-), I(-), S(2-), and SCN(-)) from a wide range of environmentally dominant anions (F(-), SO(4)(2-), H(2)PO(4)(-), CO(3)(2-), NO(3)(-), etc), identified by the change in the color of the buffered NP solution or the surface plasmon resonance (SPR) absorbance band in the UV-vis spectrum. Among the recognized anions, four types of variation in the SPR absorption band were revealed. It was strongly enhanced for Cl(-) and Br(-) and was strongly damped for S(2-). For I(-), it first was slightly enhanced at lower concentrations and then gradually was damped at higher concentrations. For SCN(-), it first was slightly damped at lower concentrations and then was strongly enhanced at higher concentrations. In response to the optical change, the color of the NP solution turned from brown to bright yellow for Cl(-) (1 mM), Br(-) (10 μM), and SCN(-) (50 μM) to brownish orange for I(-) (10 μM) and to reddish orange for S(2-) (50 μM). The reason for these phenomena was postulated by the evidence of transmission electron microscope (TEM) images, X-ray photoelectron spectroscopy (XPS), and zeta potentials. In view of the importance of anions in the environment and for human health, the Cu@Ag NP colorimetric platform may have some applications, such as discriminating household table salt (NaCl) from industrial salt (NaNO(2)), testing the quality and extent of a variety of waters, and so forth.
在水介质中识别阴离子一直是人们关注的焦点，但至今仍是一项具有挑战性的任务。在本文中，我们希望提出一种简单而灵敏的比色法检测无机阴离子的方法，基于柠檬酸盐稳定的核/壳 Cu@Ag 纳米粒子（NP）。结果发现，NP 可以通过缓冲 NP 溶液的颜色变化或表面等离子体共振（SPR）吸收带在紫外可见光谱中，从广泛的环境优势阴离子（F-、SO4(2-)、H2PO4(-)、CO3(2-)、NO3(-)等）中识别出一些特定的阴离子（Cl-、Br-、I-、S2-、SCN-）。在被识别的阴离子中，揭示了 SPR 吸收带的四种变化类型。Cl-和 Br-的吸收带强烈增强，而 S2-的吸收带强烈阻尼。对于 I-，它首先在较低浓度下略有增强，然后在较高浓度下逐渐阻尼。对于 SCN-，它首先在较低浓度下略有阻尼，然后在较高浓度下强烈增强。对于光学变化，NP 溶液的颜色从棕色变为亮黄色（Cl-（1mM）、Br-（10μM）和 SCN-（50μM）），对于 I-（10μM）为棕橙色，对于 S2-（50μM）为红橙色。这些现象的原因是通过透射电子显微镜（TEM）图像、X 射线光电子能谱（XPS）和 zeta 电位的证据来推测的。鉴于阴离子在环境和人类健康中的重要性，Cu@Ag NP 比色平台可能具有一些应用，例如从工业盐（NaNO2）中区分家用食盐（NaCl），测试各种水的质量和程度等。
