The increasing production and use of engineered inorganic nanoparticles (EINPs) escalate the risk for their unintended release into the environment. Coating of nanoparticles like natural organic matter (NOM) plays an important role in the stability, toxicity, and transport of nanoparticles. Surface‐enhanced Raman scattering (SERS) has been proven to be a promising method to detect and characterize the coating on noble metal nanoparticles. Here, we report on the synthesis of core‐shell Au–Ag nanoparticles (NPs) with a high SERS enhancement factor to study the exchange and competition of different coating agents with different binding abilities to simulate the release of NPs into a receiving environment with a number of potential coating agents. Suwannee River natural organic matter (SRNOM), 4‐mercaptobenzoic acid (4‐MBA), and 4‐mercaptopyridine (4‐MPy) were selected molecules for the experiments. The SERS experimental setup parameters such as aggregation size, laser excitation wavelength, and laser power were optimized before further experiments were conducted. It was shown that 4‐MPy has a higher binding affinity than SRNOM and 4‐MBA through the presence of simultaneous S and N atoms, which leads to dominating the coating process when two coating agents are present in the media at the same time. In addition, it was observed that 4‐MPy and 4‐MBA can replace the SRNOM coating on Au–Ag NPs.

中文翻译：

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出于环境目的，通过表面增强拉曼散射（SERS）表征金属纳米颗粒上的涂层

工程无机纳米颗粒（EINP）的生产和使用量的增加，加剧了其意外释放到环境中的风险。诸如天然有机物（NOM）之类的纳米粒子涂层在纳米粒子的稳定性，毒性和运输中起着重要作用。已证明表面增强拉曼散射（SERS）是检测和表征贵金属纳米粒子上涂层的一种有前途的方法。在这里，我们报道了具有高SERS增强因子的核-壳型Au-Ag纳米颗粒（NP）的合成，以研究具有不同结合能力的不同包衣剂的交换和竞争，从而模拟了NPs释放进入接收环境的过程。潜在的涂层剂数量。苏万尼河天然有机物（SRNOM），4-巯基苯甲酸（4-MBA）和4-巯基吡啶（4-MPy）被选择为实验的分子。在进行进一步的实验之前，先优化了SERS实验设置参数，例如聚集尺寸，激光激发波长和激光功率。结果表明，通过同时存在S和N原子，4-MPy具有比SRNOM和4-MBA更高的结合亲和力，当两种包衣剂同时存在于介质中时，这导致了包衣过程的主导地位。此外，据观察，4-MPy和4-MBA可以代替Au-Ag NP上的SRNOM涂层。结果表明，通过同时存在S和N原子，4-MPy具有比SRNOM和4-MBA更高的结合亲和力，当两种包衣剂同时存在于介质中时，这导致了包衣过程的主导地位。此外，据观察，4-MPy和4-MBA可以代替Au-Ag NP上的SRNOM涂层。结果表明，通过同时存在S和N原子，4-MPy具有比SRNOM和4-MBA更高的结合亲和力，当两种包衣剂同时存在于介质中时，这导致了包衣过程的主导地位。此外，据观察，4-MPy和4-MBA可以代替Au-Ag NP上的SRNOM涂层。