College of Chemistry and Chemical Engineering, Graduate University of Chinese Academy of Sciences, 19A YuQuan Road, Beijing 100049, China.
Biosens Bioelectron. 2011 Jan 15;26(5):2574-8. doi: 10.1016/j.bios.2010.11.007. Epub 2010 Dec 10.
A sensitive and simple colorimetric method for determination of melamine was reported based on the seedless production of gold nanoparticles (Au-NPs). Au-NPs were synthesized by using pyrocatechol-3,5-disodiumsulfonate (PD) as reducer without adding nanoparticles seeds and stabilizing agent. PD can form intramolecular hydrogen-bonding in solution by adjacent sulfurnate and α-phenolic hydroxyl group, resulting in its weak reducing capacity and thus the synthesis of Au-NPs was slow. While in the presence of melamine, PD reacted with melamine through hydrogen-bonding. Therefore, the intramolecular hydrogen-bonding of PD was interrupted by melamine, and the α-phenolic hydroxyl group was free to reduce Au(3+), hence, the synthesis of Au-NPs was accelerated. Especially, the presence of melamine led to a shift in the surface plasmon bond and a color change of Au-NPs from green to yellow. Results showed that the absorbance ratio (A(436)/A(600)) was linear with the logarithm of melamine concentration in the range of 4.8×10(-9) to 1.6×10(-6) M with a correlation coefficient of 0.9949. The detection limit (3σ) obtained by UV-vis spectrum was 6.4×10(-10) M (i.e., 0.08 ppb). The proposed method was applied successfully to the determination of melamine in pretreated liquid milk products, and the recoveries were from 93% to 107%.
基于金纳米粒子（Au-NPs）无种生成的灵敏且简单的比色法测定了三聚氰胺。通过使用邻苯二酚-3,5-二磺酸钠（PD）作为还原剂，无需添加纳米颗粒种子和稳定剂，即可合成 Au-NPs。PD 可通过相邻的磺酸盐和α-酚羟基在溶液中形成分子内氢键，导致其还原能力较弱，因此 Au-NPs 的合成速度较慢。然而，在三聚氰胺存在的情况下，PD 通过氢键与三聚氰胺反应。因此，PD 的分子内氢键被三聚氰胺打断，α-酚羟基可以自由还原 Au(3+)，从而加速了 Au-NPs 的合成。特别是，三聚氰胺的存在导致 Au-NPs 的表面等离子体键发生位移，颜色从绿色变为黄色。结果表明，在 4.8×10(-9) 至 1.6×10(-6) M 的范围内，吸光度比（A(436)/A(600)）与三聚氰胺浓度的对数呈线性关系，相关系数为 0.9949。通过紫外-可见光谱获得的检测限（3σ）为 6.4×10(-10) M（即 0.08 ppb）。该方法成功应用于预处理液态奶产品中三聚氰胺的测定，回收率为 93%至 107%。
