Visualization of molecular trapping at plasmonic metal nanostructure by surface-enhanced Raman scattering imaging
Visualization of molecular trapping at plasmonic metal nanostructure by surface-enhanced Raman scattering imaging
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DOI：
10.1117/1.jnp.14.026001
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发表时间：
2020-04
影响因子：
1.5
通讯作者：
Tomohiro Fukushima;Akira Miyauchi;Nobuaki Oyamada;Hiro Minamimoto;Toshinori Motegi;K. Murakoshi
中科院分区：
文献类型：
--
作者：
Tomohiro Fukushima;Akira Miyauchi;Nobuaki Oyamada;Hiro Minamimoto;Toshinori Motegi;K. Murakoshi
摘要。光镊技术已被用于捕获微米级的物体，但在室温下控制纳米级小分子的运动仍然很困难。等离子体金属纳米结构有望利用高度局域化的电场对纳米级分子进行光操控。我们利用等离子体银纳米结构，通过表面增强拉曼散射（SERS）成像观察来演示光捕获。在电化学电位控制下进行光学测量，以使目标分子4,4′ - 联吡啶（44bpy）稳定在纳米结构上。在室温下，随着电解质溶液中44bpy分子浓度的增加，SERS信号的闪烁频率在光谱和成像中均有所不同。SERS信号的持续时间从几十毫秒增加到几秒，这表明通过表面扩散控制成功观察到了小分子的等离子体捕获。观察结果证明了控制分子的表面覆盖度及其在等离子体分子捕获下对表面扩散的影响的重要性。
Abstract. Optical manipulation has been used for the trapping of micrometer-scaled objects, but it is still difficult to control the motion of small molecules on the nanometer scale at room temperature. Plasmonic metal nanostructures are expected to be useful for the optical manipulation of nanoscale molecules using a highly localized electric field. We use the plasmonic Ag nanostructure for a demonstration of optical trapping through the observation using surface-enhanced Raman scattering (SERS) imaging. The optical measurements were conducted under electrochemical potential control to stabilize the nanostructure with target molecules, 4,4′-bipyridyl (44 bpy). Upon increasing the concentration of 44 bpy molecules in an electrolyte solution at room temperature, the blinking frequency of the SERS signal was different in both the spectra and imaging. The dwell time of the SERS signals was increased from several tens of milliseconds to a few seconds, which suggested the successful observation of plasmonic trapping of small molecules through the surface diffusion control. The observed results prove the importance for the control of the surface coverage of the molecules and its influence on surface diffusion under plasmonic molecular trapping.