Fabrication of SERS-Active Au@Au@Ag Double Shell Nanoparticles for Low-Abundance Pigment Detection

Au@Au@Ag double shell nanoparticles were fabricated and characterized using TEM, STEM-mapping and UV-Vis methods. Using crystal violet as Raman probe, the surface-enhanced Raman scattering (SERS) activity of the as-prepared Au@Au@Ag nanoparticles was studied by comparing to Au, Au@Ag and Au@Au core-shell nanoparticles which were prepared by the same methods. Moreover, it can be found that the SERS activity was enhanced obviously by introduction of NaCl and the concentrations of NaCl played a key role in SERS detection. With an appropriate concentration of NaCl, the limit of detection as low as 10\begin{document}$ ^{-10} $\end{document} mol/L crystal violet can be achieved. The possible enhanced mechanism was also discussed. Furthermore, with simple sample pretreatment, the detection limit of 5 μg/g Rhodamine B (RhB) in chili powders can be achieved. The results highlight the potential utility of Au@Au@Ag for detection of illegal food additives with low concentrations.     

用于低丰度添加剂检测的具有表面增强拉曼光谱活性的Au@Au@Ag双壳核纳米粒子的制备

本文合成了Au@Au@Ag双壳核纳米粒子,并利用透射电子显微镜、扫描电子显微镜和紫外可见光谱进行了表征. 以结晶紫作为拉曼探针,并与相同方法制备的Au、Au@Ag和Au@Au核壳纳米粒子比较,发现其表面增强拉曼光谱活性明显增强. 通过引入氯化钠,发现所得材料的表面增强拉曼光谱活性进一步增强,氯化钠浓度在表面增强拉曼光谱检测中起着关键作用. 在适当的氯化钠浓度下,检测限可低至10^-10 mol/L,并讨论了其中可能的增强机制. 通过简单的样品预处理,利用该材料作为基底可以检测辣椒粉中罗丹明B,检出限可达5 μg/g. 该研究表明Au@Au@Ag 双壳核纳米粒子在检测低浓度非法食品添加剂方面具有潜在用途.