Institute of Chemistry, University of Campinas - UNICAMP, P.O. Box 6154, 13083-970 Campinas, SP, Brazil.
Institute of Chemistry, University of Campinas - UNICAMP, P.O. Box 6154, 13083-970 Campinas, SP, Brazil.
Spectrochim Acta A Mol Biomol Spectrosc. 2020 Apr 15;231:118113. doi: 10.1016/j.saa.2020.118113. Epub 2020 Jan 30.
Rod-shaped gold-silver core-shells (AuNR@Ag) were synthesized for an analysis of the amplification of Raman scattering (surface-enhanced Raman scattering, SERS). The microscopy characterization confirmed a hierarchically structured nanoparticle with well-defined size and morphology, however, with a degree of dispersion in terms of shell thickness and symmetry of Ag deposition. In this paper, we analyze the possible effects of such structural dispersion in the SERS spectra of 4-aminobenzothiol (4-ABT) and in its detection at low concentrations in solutions. The interpretation of experimental results was supported by classical electrodynamics simulations based on the boundary element method (BEM). We verified that even in the case of asymmetrical Ag deposition onto AuNRs, a large SERS normal may be observed, which leads to the possibility of using such nanostructures for SERS applications aiming at low analyte concentrations detections. We show that the SERS substrates based on such AuNR@Ag present very high sensitivity for the detection of ultra-low concentrations of 4-ABT reaching a detection limit of 1.10 mol L, which indicates the possibility of analytical applications in the detection of analytes such as pesticides.
棒状金银核壳（AuNR@Ag）被合成用于分析拉曼散射（表面增强拉曼散射，SERS）的放大作用。显微镜特征证实了具有良好定义的尺寸和形态的分级结构纳米粒子，但在壳厚度和 Ag 沉积对称性方面存在一定程度的分散性。在本文中，我们分析了这种结构分散性对 4-巯基苯硼酸（4-ABT）的 SERS 光谱及其在溶液中低浓度检测中的可能影响。实验结果的解释得到了基于边界元法（BEM）的经典电动力学模拟的支持。我们验证了，即使在 AuNR 上不对称地沉积 Ag 的情况下，也可能观察到较大的 SERS 正常，这使得此类纳米结构有可能用于旨在检测低浓度分析物的 SERS 应用。我们表明，基于这种 AuNR@Ag 的 SERS 基底对 4-ABT 的超低浓度检测具有非常高的灵敏度，检测限达到 1.10 mol L，这表明在检测农药等分析物的分析应用中具有可能性。
