Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei 230031, China.
Department of Chemistry, University of Science and Technology of China , Hefei 230026, China.
Anal Chem. 2017 May 2;89(9):4875-4881. doi: 10.1021/acs.analchem.6b04688. Epub 2017 Apr 11.
Surface-enhanced Raman spectroscopy (SERS) as a powerful qualitative analysis method has been widely applied in many fields. However, SERS for quantitative analysis still suffers from several challenges partially because of the absence of stable and credible analytical strategy. Here, we demonstrate that the optimal hotspots created from dynamic surfaced-enhanced Raman spectroscopy (D-SERS) can be used for quantitative SERS measurements. In situ small-angle X-ray scattering was carried out to in situ real-time monitor the formation of the optimal hotspots, where the optimal hotspots with the most efficient hotspots were generated during the monodisperse Au-sol evaporating process. Importantly, the natural evaporation of Au-sol avoids the nanoparticles instability of salt-induced, and formation of ordered three-dimensional hotspots allows SERS detection with excellent reproducibility. Considering SERS signal variability in the D-SERS process, 4-mercaptopyridine (4-mpy) acted as internal standard to validly correct and improve stability as well as reduce fluctuation of signals. The strongest SERS spectra at the optimal hotspots of D-SERS have been extracted to statistics analysis. By using the SERS signal of 4-mpy as a stable internal calibration standard, the relative SERS intensity of target molecules demonstrated a linear response versus the negative logarithm of concentrations at the point of strongest SERS signals, which illustrates the great potential for quantitative analysis. The public drugs 3,4-methylenedioxymethamphetamine and α-methyltryptamine hydrochloride obtained precise analysis with internal standard D-SERS strategy. As a consequence, one has reason to believe our approach is promising to challenge quantitative problems in conventional SERS analysis.
表面增强拉曼光谱（SERS）作为一种强大的定性分析方法，已广泛应用于许多领域。然而，SERS 定量分析仍然存在一些挑战，部分原因是缺乏稳定和可靠的分析策略。在这里，我们证明可以将动态表面增强拉曼光谱（D-SERS）产生的最佳热点用于定量 SERS 测量。原位小角 X 射线散射用于原位实时监测最佳热点的形成，其中在单分散金溶胶蒸发过程中会产生具有最高效率热点的最佳热点。重要的是，金溶胶的自然蒸发避免了盐诱导的纳米粒子不稳定性，有序的三维热点的形成允许具有出色重现性的 SERS 检测。考虑到 D-SERS 过程中 SERS 信号的可变性，4-巯基吡啶（4-mpy）用作内标，有效地校正和改善稳定性并降低信号波动。从 D-SERS 的最佳热点中提取最强的 SERS 光谱进行统计分析。通过使用 4-mpy 的 SERS 信号作为稳定的内部校准标准，目标分子的相对 SERS 强度与最强 SERS 信号点处的浓度的负对数呈线性响应，这说明了定量分析的巨大潜力。通过使用内标 D-SERS 策略，对公开的毒品 3,4-亚甲二氧基甲基苯丙胺和盐酸α-甲基色胺进行了精确分析。因此，有理由相信我们的方法很有希望挑战传统 SERS 分析中的定量问题。
