School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States.
Nano Lett. 2024 Sep 18;24(37):11607-11614. doi: 10.1021/acs.nanolett.4c03155. Epub 2024 Sep 9.
Fourier transform infrared (FTIR) spectroscopy is widely used for molecular analysis. However, for the materials situated in an aqueous environment, a precondition for live biological objects such as cells, transmission-based FTIR is prevented by strong water absorption of mid-infrared (MIR) light. Reflection-based cellular assays using internal reflection elements (IREs) such as high-index prisms or flat plasmonic metasurfaces mitigate these issues but suffer from a shallow probing volume localized near the plasma membrane. Inspired by the recent introduction of high-aspect-ratio nanostructures as a novel platform for manipulating cellular behavior, we demonstrate that the integration of plasmonic metasurfaces with tall dielectric nanostructures dramatically enhances the sensing capabilities of FTIR spectroscopy. We also demonstrate the ability of a metal-on-dielectric metasurface to transduce intracellular processes, such as protein translocation to high-curvature membrane regions during cell adhesion, into interpretable spectral signatures of the reflected light.
傅里叶变换红外（FTIR）光谱广泛用于分子分析。然而，对于处于水相环境中的材料，对于诸如细胞的活体生物对象，由于中红外（MIR）光的强烈水吸收，基于透射的 FTIR 受到阻碍。使用内部反射元件（IRE）的基于反射的细胞分析，例如高折射率棱镜或平面等离子体超表面，可以减轻这些问题，但探测体积浅，局限于靠近质膜的位置。受最近引入高纵横比纳米结构作为一种新型平台来操纵细胞行为的启发，我们证明了等离子体超表面与高介电纳米结构的集成可以极大地增强 FTIR 光谱的传感能力。我们还展示了金属-介质超表面将细胞内过程（例如在细胞黏附过程中蛋白质向高曲率膜区的易位）转化为反射光的可解释光谱特征的能力。
