【摘要】 负电性金或银纳米粒子（Au/Ag NPs）溶胶是目前使用最广泛的表面增强拉曼光谱（SERS）基底，由于静电斥力导致其对负电性分子的检测灵敏度极低。为解决此难题，研究者一方面采用正电性分子作为保护剂，制备了正电性SERS基底，但灵敏度仅为mg/L级；另一方面，引入巯基乙胺等正电性桥联分子，虽然灵敏度提高到μg/L级，但实验操作条件苛刻，难以满足实际应用需求。针对上述问题，本研究引入硫脲作为桥联分子用于SERS检测负电性分子。硫脲分子不仅可更有效地捕获负电性分子进入SERS热点，而且显著降低了实验操作难度。本方法对含磺酸根的日落黄和含羧酸根的酸性红94等10种负电性分子的最低可检出浓度达到10 μg/L水平，为复杂体系中痕量负电性分子的SERS快速检测提供了方法学上的可行性。更多还原

【Abstract】 The negatively charged Au/Ag colloidal nanoparticles(NPs) with sodium citrate as reducing agent are the most widely used colloidal surface-enhanced Raman spectroscopy(SERS) substrate at present. Due to the electrostatic repulsion, the detection sensitivity towards negatively charged molecules is extremely low. To solve this issue, two strategies have been proposed, including(1) the positive Au/Ag colloidal NPs was synthesized using positive molecules, as protective agents, which could realize the negative molecule detection at the mg/L level, and(2) the positive molecule, such as mercaptoethylamine, was introduced as the linker to connect the negative colloid and the negative target. Although a high sensitivity atμg/L level was realized, the experimental operation was harsh, and it was difficult for the potential practical application. In view of this situation, thiourea was introduced as a linker molecule in this study, which not only provided more positively charged amino groups to capture negatively charged molecules into the SERS hot spots, but the relatively weaker surface binding ability significantly made the experimental operation easier. With the molecules containing sulfonate such as sunset yellow, or carboxylate such as acid red 94, as the targets, the sensitive detection of 10 typical negatively charged molecules was realized with the lowest detectable concentration of 10 μg/L to 1 mg/L. This study paved a way for SERS detection of trace negatively charged molecules in complex systems in a fast and sensitive manner.更多还原