Hu Huatian, Xu Yuhao, Hu Zhiwei, Kang Bowen, Zhang Zhenglong, Sun Jiawei, Li Yang, Xu Hongxing
School of Electronics and Information Engineering, Shenzhen University, Shenzhen 518060, China.
Hubei Key Laboratory of Optical Information and Pattern Recognition, Wuhan Institute of Technology, Wuhan 430205, China.
Nanophotonics. 2022 Oct 27;11(22):5153-5163. doi: 10.1515/nanoph-2022-0521. eCollection 2022 Dec.
Surface-enhanced spectroscopies, such as surface-enhanced Raman scattering (SERS), fluorescence (SEF), circular dichroism, etc., are powerful tools for investigating nano-entities with high sensitivities. Owing to the giant local electric field confined in a plasmonic nanogap, nanogap-enhanced spectroscopies could detect samples with ultralow concentrations, even down to the single-molecule level for SERS and SEF. This great ability to detect analytes with ultralow concentrations provides opportunities for early diagnosis and monitoring in modern biomedicine. However, local laser excitations would inevitably bring about unwanted disruptive background perturbations, local heating, and the consequent geometry reshaping and biological analyte damages. Remote spectroscopies avoiding direct laser exposure to the samples can be treated as remarkable solutions. Here, we combined the nanoparticle-on-mirror (NPoM) family with the philosophy of remote spectroscopy to construct so-called "NPoM pairs" structures. They consist of two identical NPoMs with matched resonances yet separate functions either as receiving or transmitting antennas. A figure of merit for evaluating the remote spectroscopies was put forward, which accounts for the efficiencies in three processes, i.e., receiving, transporting, and transmitting. In addition, we experimentally demonstrated the performances of these NPoM pairs by proof-of-principle applications on the remote SERS and SEF. The optical access of the spectral information in these NPoM pairs both locally and remotely manifests themselves as fundamental building blocks for remote spectroscopies.
表面增强光谱技术，如表面增强拉曼散射（SERS）、荧光（SEF）、圆二色性等，是用于高灵敏度研究纳米实体的强大工具。由于局域在等离子体纳米间隙中的巨大局部电场，纳米间隙增强光谱技术能够检测超低浓度的样品，对于SERS和SEF甚至能低至单分子水平。这种检测超低浓度分析物的强大能力为现代生物医学中的早期诊断和监测提供了机会。然而，局部激光激发不可避免地会带来不必要的破坏性背景干扰、局部加热以及随之而来的几何形状重塑和生物分析物损伤。避免激光直接照射样品的远程光谱技术可被视为显著的解决方案。在此，我们将镜上纳米颗粒（NPoM）家族与远程光谱技术理念相结合，构建了所谓的“NPoM对”结构。它们由两个具有匹配共振但功能不同的相同NPoM组成，分别作为接收或发射天线。提出了一种用于评估远程光谱技术的品质因数，该品质因数考虑了接收、传输和发射三个过程的效率。此外，我们通过在远程SERS和SEF上的原理验证应用，实验证明了这些NPoM对的性能。这些NPoM对中光谱信息的局部和远程光学获取本身就体现为远程光谱技术的基本构建模块。
