Department of Chemistry , Key Laboratory of Resource Chemistry of Ministry of Education , 100 Guilin Road , Shanghai 200234 , People's Republic of China.
ACS Appl Mater Interfaces. 2018 May 9;10(18):15412-15417. doi: 10.1021/acsami.8b01765. Epub 2018 Apr 24.
Abuse of methenamine in foodstuff is harmful to the health of people. Routine methods recommended by the national standard are indirect assays with complicated pretreatment of samples or less sensitivity. In this work, core-shell Au nanoparticles@inositol hexaphosphate@MIL-101(Fe) nanoparticles, designated as Au@MIL-101, are successfully synthesized by layer-by-layer assembly. Metal-organic framework (MOF; MIL-101)-modified AuNPs could narrow the distance between neighboring Au@MIL-101, which increases the amount of "hot spots" and contributes excellent enhancement of Raman scattering. In addition, certain target molecules could access the proximity to the "hot spots" by the strong interaction capability of MOF with -COOH groups. Taking the syngeneic effect of "hot spots" and chemical enhancement via specific binding, Au@MIL-101-based Raman protocol with huge sensitivity is developed to achieve direct detection of methenamine. It has good linearity of dynamic concentration from 3.16 × 10 to 1.0 × 10 M with correlation coefficient ( R) of 0.9908. The limit of detection reaches 5.0 × 10 M. As a practical application, such an Au@MIL-101-based Raman protocol could be used for the direct determination of trace methenamine in vermicelli, which meets the requirements of the national standard.
食用三聚氰胺是有害于人体健康的。国家标准中推荐的常规方法是间接检测，样品预处理复杂或灵敏度较低。在这项工作中，通过层层组装成功合成了核壳型金纳米粒子@肌醇六磷酸@MIL-101(Fe)纳米粒子，命名为 Au@MIL-101。金属有机骨架（MOF；MIL-101）修饰的 AuNPs 可以缩小相邻 Au@MIL-101 之间的距离，增加“热点”的数量，并对拉曼散射产生优异的增强效果。此外，某些目标分子可以通过 MOF 与-COOH 基团的强相互作用接近“热点”。利用“热点”的协同效应和特定结合的化学增强作用，开发了基于 Au@MIL-101 的拉曼方案，具有巨大的灵敏度，可实现对三聚氰胺的直接检测。该方案在 3.16×10 到 1.0×10 M 的动态浓度范围内具有良好的线性关系，相关系数（R）为 0.9908。检测限达到 5.0×10 M。作为实际应用，该基于 Au@MIL-101 的拉曼方案可用于粉丝中痕量三聚氰胺的直接测定，符合国家标准要求。
