Toxic, carcinogenic, and mutagenic properties of polycyclic aromatic hydrocarbons (PAHs) and environmental pollution caused by polycyclic aromatic sulfur heterocycles (PASHs) postulate the importance of their selective and sensitive determination in environmental and oil fuel samples. Surface-enhanced Raman spectroscopy (SERS) opens up an avenue toward multiplex analysis of complex mixtures, however not every molecule gives high enhancement factors and, thus, cannot be reliably detected via SERS. However, the sensitivity can be drastically increased by additional resonant enhancement as a result of the analyte absorption band overlapping with the surface plasmon band of nanoparticles (NPs) and the laser excitation wavelength. Using this idea, we developed a dual-purpose SERS sensor based on trapping the target PAHs and PASHs into colored charge-transfer complexes (CTCs) with selected organic π-acceptor molecules on the surface of AgNPs. Studying, computing, and then comparing stability constants of the formed CTC served as a powerful explanation and prediction tool for a wise choice of π-acceptor indicator systems for the further silver surface modification. Moreover, we show that CTC formation can be effectively utilized for increasing both selectivity and sensitivity by simple liquid–liquid extraction prior to SERS measurements. For the first time, the dual-purpose SERS sensor allowed determination of two different classes of polycyclic aromatic fuel components down to 10 nM concentration, lower than that restricted by the ASTM regulation, and demonstrated multi-purpose capabilities of the developed approach.

中文翻译：

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双用途SERS传感器，用于通过电子供体-受体陷阱选择性测定多环芳族化合物

多环芳烃（PAH）的有毒，致癌和致突变性，以及多环芳族硫杂环（PASH）造成的环境污染，是在环境和燃油样品中进行选择性和灵敏测定的重要前提。表面增强拉曼光谱（SERS）为复杂混合物的多元分析开辟了道路，但是并非每个分子都能提供高增强因子，因此无法通过SERS。但是，由于分析物吸收带与纳米颗粒（NPs）的表面等离激元带和激光激发波长重叠，因此可以通过额外的共振增强来大大提高灵敏度。利用这个想法，我们开发了一种两用SERS传感器，其基础是将目标PAH和PASH捕获到有色电荷转移络合物（CTC）中，该电荷转移络合物具有在AgNP表面上选择的有机π受体分子。研究，计算并比较形成的CTC的稳定常数，为明智选择π受体指示剂系统进行进一步的银表面修饰提供了有力的解释和预测工具。此外，我们表明在SERS测量之前，通过简单的液-液萃取，四氯化碳的形成可以有效地用于提高选择性和灵敏度。