Ag纳米粒子修饰光纤探针在等离激元催化反应中的应用

Application of Ag Nanoparticle-Modified Fiber Probe for Plasmonic Catalysis Reaction

本文发展了一种基于Ag纳米粒子(AgNPs)修饰的局域表面等离激元共振(LSPR)光纤探针,作为等离激元催化反应基底同时原位检测表面增强拉曼光谱(SERS)信号,实现反应与检测一体化。本文使用(3-氨基丙基)三甲氧基硅烷(APTMS)分子将AgNPs组装到光纤探针表面。通过调控自组装时间,可形成AgNPs均匀分布的探针。以对巯基苯胺(PATP)作为反应的模型分子,获得了较好的等离激元催化及信号检测效果。在相同光源条件下,从光纤内部激发收集所得产物的SERS信号强度为外部激发收集的12.8倍,表明内激发收集方式在反应及信号检测方面具有优势;在一定浓度范围(10^(-4)–10^(-8)mol·L^(-1))内可用该光纤探针对PATP溶液进行定量分析;运用该光纤探针开展了等离激元催化PATP分子偶联反应的原位动力学研究。该LSPR光纤探针具有较高灵敏度,对样品损伤小,可在多场合下实现原位检测,且制备简便、成本较低。还有望结合近场扫描光学显微技术进一步对样品表面进行微区等离激元催化反应及检测并得到反应的二维分布图。

In this study, a localized surface plasmon resonance (LSPR) fiber probe modified with Ag nanoparticles (NPs) was developed. The LSPR fiber probe not only serves as a reaction substrate for plasmonic catalysis, but also detects in situ surface-enhanced Raman spectroscopy (SERS) signals from the reaction product, thereby achieving the integration of the plasmonic catalysis reactions and SERS signal detection. To fabricate the LSPR probe, plasmonic Ag NPs were first selfassembled on the surface of the fiber probe with assistance by the amination and silanization of (3-aminopropyl) trimethoxysilane (APTMS) molecules. p-Aminothiophenol (PATP) was chosen as a model molecule for plasmonic catalytic reaction. By regulating the self-assembly time of the Ag NPs, a uniform distributed monolayer of Ag NPs was formed on the surface of the probe, with which excellent plasmonic catalysis effects and SERS signal collection from the reaction product of 4,4′-dimercaptoazobenzene (DMAB) were achieved. It was found that the characteristic SERS signal of the plasmonic catalytic reaction product DMAB obtained from internal excitation and collection was 12.8 times more intense than that from the external excitation and collection under the same laser intensity conditions, demonstrating that the internal excitation and collection method was advantageous in the plasmonic catalysis and SERS signal detection. The LSPR fiber probe was demonstrably qualified to quantitatively detect the concentrations of PATP solutions in the concentration ranges 10?4–10?8 mol·L?1. Using the LSPR fiber probe, we also realized an in situ kinetics study of the PATP coupling reaction enhanced by plasmonic catalysis. The results showed that the Ag NP-based LSPR fiber probe with internal excitation and collection modes had the advantages of high sensitivity, low cost, facile preparation, and most importantly, applicability to in situ detection in a flexible manner with less damage to the samples. The preliminary study also indicated that it was feasible to combine the LSPR fiber probe with near-field scanning optical microscopy, not only to obtain morphological images of the surface but also to simultaneously perform the plasmonic catalysis reaction and the detection of micro-domains of the surface. This permitted the acquisition of a two-dimensional distributional assessment of surface reactions by the plasmonic catalysis.