Gold-coated silver nanowires for long lifetime AFM-TERS probes
Gold-coated silver nanowires for long lifetime AFM-TERS probes
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用于长寿命 AFM-TERS 探针的镀金银纳米线
DOI：
10.1039/d1nr07833j
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发表时间：
2022
期刊：
影响因子：
6.7
通讯作者：
Uji-i Hiroshi
中科院分区：
文献类型：
--
作者：
Wen Han;Inose Tomoko;Hirai Kenji;Akashi Taiki;Sugioka Shoji;Li Jiangtao;Peeters Wannes;Fron Eduard;Fortuni Beatrice;Nakata Yoshihiko;Rocha Susana;Toyouchi Shuichi;Fujita Yasuhiko;Uji-i Hiroshi
尖端增强拉曼散射（TERS）显微镜是一种先进的纳米级研究技术，具有无标记、无创、能同时提供形貌和化学信息等优点。探测器在TERS技术性能中起着至关重要的作用。用金属沉积制造的广泛使用的AFM-TERS探针遭受相对低的再现性以及有限的映射和存储寿命。为了解决再现性问题，开发了基于银纳米线（AgNW）的TERS探针，由于AgNW的液相合成的高度均匀性，其可以实现具有优异的探针再现性的高TERS性能，但由于探针氧化，仍然存在短寿命。在这项工作中，一个简单的Au涂层的方法，提出了克服有限的寿命和提高性能的AgNW基TERS探针。对于Au涂层，研究了不同的[Au]/[Ag]摩尔比。TERS的性能进行了评估的增强因子（EF）和信号噪声比的变化，通过多次映射和在空气中的存储寿命。Au涂覆的AgNWs表现出比原始AgNWs更高的EF，并且电镀取代AgNWs，测试的两个摩尔比之间没有显著差异。然而，对于较长的扫描时间和多次映射，用低Au浓度获得的探针显示出长得多的长期稳定性，并保持高EF。此外，Au涂层的AgNW探针被发现具有在空气中的较长的存储寿命，允许长的和多个TERS映射与一个单一的探针。
Tip-enhanced Raman scattering (TERS) microscopy is an advanced technique for investigation at the nanoscale because of its excellent properties, such as its label-free functionality, non-invasiveness, and ability to simultaneously provide topographic and chemical information. The probe plays a crucial role in TERS technique performance. Widely used AFM-TERS probes fabricated with metal deposition suffer from relatively low reproductivity as well as limited mapping and storage lifetime. To solve the reproducibility issue, silver nanowire (AgNW)-based TERS probes were developed, which, thanks to the high homogeneity of the liquid-phase synthesis of AgNW, can achieve high TERS performance with excellent probe reproductivity, but still present short lifetime due to probe oxidation. In this work, a simple Au coating method is proposed to overcome the limited lifetime and improve the performance of the AgNW-based TERS probe. For the Au-coating, different [Au]/[Ag] molar ratios were investigated. The TERS performance was evaluated in terms of changes in the enhancement factor (EF) and signal-to-noise ratio through multiple mappings and the storage lifetime in air. The Au-coated AgNWs exhibited higher EF than pristine AgNWs and galvanically replaced AgNWs with no remarkable difference between the two molar ratios tested. However, for longer scanning time and multiple mappings, the probes obtained with low Au concentration showed much longer-term stability and maintained a high EF. Furthermore, the Au-coated AgNW probes were found to possess a longer storage lifetime in air, allowing for long and multiple TERS mappings with one single probe.