CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China.
Adv Mater. 2022 Jul;34(27):e2110525. doi: 10.1002/adma.202110525. Epub 2022 May 29.
Identifying nanoscale biomolecules in aqueous solutions by Fourier transform infrared spectroscopy (FTIR) provides an in situ and noninvasive method for exploring the structure, reactions, and transport of biologically active molecules. However, this remains a challenge due to the strong and broad IR absorption of water which overwhelms the respective vibrational fingerprints of the biomolecules. In this work, a tunable IR transparent microfluidic system with graphene plasmons is exploited to identify ≈2 nm-thick proteins in physiological conditions. The acquired in situ tunability makes it possible to eliminate the IR absorption of water outside the graphene plasmonic hotspots by background subtraction. Most importantly, the ultrahigh confinement of graphene plasmons (confined to ≈15 nm) permits the implementation of nanoscale sensitivity. Then, the deuterium effects on monolayer proteins are characterized within an aqueous solution. The tunable graphene-plasmon-enhanced FTIR technology provides a novel platform for studying biological processes in an aqueous solution at the nanoscale.
通过傅里叶变换红外光谱（FTIR）在水溶液中识别纳米级生物分子为探索生物活性分子的结构、反应和输运提供了一种原位和非侵入性的方法。然而，由于水的强而宽的红外吸收，这淹没了生物分子各自的振动指纹，因此这仍然是一个挑战。在这项工作中，利用可调谐的 IR 透明微流控系统与石墨烯等离子体来识别生理条件下 ≈2nm 厚的蛋白质。所获得的原位可调谐性使得通过背景扣除来消除石墨烯等离子体热点以外的水的红外吸收成为可能。最重要的是，石墨烯等离子体的超高限制（限制在 ≈15nm 内）允许实现纳米级灵敏度。然后，在水溶液中对单层蛋白质的氘效应进行了表征。可调谐的石墨烯等离子体增强 FTIR 技术为在纳米尺度上研究水溶液中的生物过程提供了一个新的平台。
