Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States.
Hematology/Oncology Division, Department of Medicine, University of California, Irvine, California 92697, United States.
Nano Lett. 2020 Sep 9;20(9):6697-6705. doi: 10.1021/acs.nanolett.0c02575. Epub 2020 Aug 27.
Plasmonic sensors are commonly defined on two-dimensional (2D) surfaces with an enhanced electromagnetic field only near the surface, which requires precise positioning of the targeted molecules within hotspots. To address this challenge, we realize segmented nanocylinders that incorporate plasmonic (1-50 nm) gaps within three-dimensional (3D) nanostructures (nanocylinders) using electron irradiation triggered self-assembly. The 3D structures allow desired plasmonic patterns on their inner cylindrical walls forming the nanofluidic channels. The nanocylinders bridge nanoplasmonics and nanofluidics by achieving electromagnetic field enhancement and fluid confinement simultaneously. This hybrid system enables rapid diffusion of targeted species to the larger spatial hotspots in the 3D plasmonic structures, leading to enhanced interactions that contribute to a higher sensitivity. This concept has been demonstrated by characterizing an optical response of the 3D plasmonic nanostructures using surface-enhanced Raman spectroscopy (SERS), which shows enhancement over a 22 times higher intensity for hemoglobin fingerprints with nanocylinders compared to 2D nanostructures.
等离子体激元传感器通常在二维（2D）表面上定义，只有在表面附近才有增强的电磁场，这需要将目标分子精确定位于热点位置。为了解决这一挑战，我们使用电子辐照触发自组装技术，在三维（3D）纳米结构（纳米圆柱）中实现了包含等离子体（1-50nm）间隙的分段纳米圆柱。3D 结构允许在其内部圆柱壁上形成纳米流道的所需等离子体图案。纳米圆柱通过同时实现电磁场增强和流体限制来连接纳米等离子体学和纳米流体学。这种混合系统使目标物种能够快速扩散到 3D 等离子体结构中的更大空间热点，从而增强相互作用，提高灵敏度。这一概念通过使用表面增强拉曼光谱（SERS）对 3D 等离子体纳米结构的光学响应进行了表征，结果表明，与 2D 纳米结构相比，纳米圆柱的血红蛋白指纹的强度增强了 22 倍以上。
