Blue-to-Red Colorimetric Sensing Strategy for Hg2+ and Ag+ via Redox-Regulated Surface Chemistry of Gold Nanoparticles
Blue-to-Red Colorimetric Sensing Strategy for Hg2+ and Ag+ via Redox-Regulated Surface Chemistry of Gold Nanoparticles
复制标题
通过氧化还原调节的金纳米粒子表面化学对 Hg2 和 Ag 进行蓝到红比色传感策略
DOI：
10.1021/am200130e
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发表时间：
2011-05-01
影响因子：
9.5
通讯作者：
Chen, Lingxin
中科院分区：
文献类型：
--
作者：
Lou, Tingting;Chen, Zhaopeng;Chen, Lingxin
本文报道了一种基于抗坏血酸（AA）氧化还原形成的金属涂层稳定金纳米粒子（AuNPs）的“蓝变红”比色法测定汞离子（Hg 2+）和银离子（Ag+）。首先在具有高离子强度的磷酸盐缓冲溶液中用吐温20稳定金纳米颗粒。在无靶离子体系中，N-乙酰-L-半胱氨酸的加入导致Tween 20稳定的金纳米粒子聚集，巯基配体自组装在金纳米粒子表面，导致金纳米粒子不稳定。这将导致颜色从红色变为蓝色。而在含Hg ~（2+）或Ag ~+的水溶液中，AA可将Hg ~（2+）或Ag ~+还原成Hg-Au合金或在金纳米粒子表面形成Ag包覆层。这种金属涂层阻止巯基配体组装，并且在添加N-乙酰基-L-半胱氨酸后，AuNPs保持单分散，表现出红色。因此，利用这一机制，可以建立一个“蓝到红”的比色传感策略，用于检测He 2+和Ag+。与通常报道的基于聚集体的方法（“红变蓝”）相比，从蓝色到红色的颜色变化似乎更人眼敏感，特别是在低浓度的目标。利用目标离子的氧化还原性质和经典的离子掩蔽剂，避免了离子螯合基团的设计和选择以及复杂的金表面修饰过程，实现了对Hg ~（2+）和Ag ~+的选择性分析。该方法可以选择性地检测低至5 nM和10 nM的纯水中的Hg 2+和Ag+，线性范围分别为5 x 10（-7）至1 x 10（-5）M的Hg 2+和1 x 10（-6）至8 x 10（-6）M的Ag+。应用于自来水和饮用水中Hg ~（2+）和Ag ~+的测定。
Here we report a "blue-to-red" colorimetric method for determination of mercury ions (Hg2+) and silver ions (Ag+) based on stabilization of gold nanoparticles (AuNPs) by redox formed metal coating in the presence of ascorbic acid (AA). AuNPs were first stabilized by Tween 20 in phosphate buffer solution with high ionic strength. In a target ion-free system, the addition of N-acetyl-L-cysteine resulted in the aggregation of Tween 20 stabilized AuNPs for mercapto ligand self-assembled on the surface of AuNPs, which induced the AuNPs to be unstable. This would lead to a color change from red to blue. By contrast, in an aqueous solution with Hg2+ or Ag+, the ions could be reduced with the aid of AA to form Hg-Au alloy or Ag coating on the surface of AuNPs. This metal coating blocked mercapto ligand assembly and AuNPs kept monodispersed after addition of N-acetyl-L-cysteine, exhibiting a red color. Therefore, taking advantage of this mechanism, a "blue-to-red" colorimetric sensing strategy could be established for He2+ and Ag+ detection. Compare with the commonly reported aggregation-based method ('red-to-blue'), the color change from blue to red seems more eye-sensitive, especial in low concentration of target. Moreover, selective analysis of Hg2+ and Ag+ was simply achieved by the redox nature of target ions and the application of classic ion masking agents, avoiding the design and selection of ion chelating moieties and complicated gold surface modification procedure. This method could selectively detect Hg2+ and Ag+ as low as 5 nM and 10 nM in pure water with a linear range of 5 x 10(-7) to 1 x 10(-5) M for Hg2+ and 1 x 10(-6) to 8 x 10(-6) M for Ag+, respectively. It was successfully applied to determination of Hg2+ and Ag+ in tap water and drinking water.