Ultrasensitive Mid‐Infrared Biosensing in Aqueous Solutions with Graphene Plasmons

• DOI: 10.1002/adma.202110525
• Publication Date: 2022-04-23T01:09:11Z
• Authors: Chenchen Wu; Xiangdong Guo; Yu Duan; Wei Lyu; Hai Hu; Debo Hu; Ke Chen; Zhipei Sun; Teng Gao; Xiaoxia Yang; Qing Dai
• Keywords: aqueous solutions; surface-enhanced infrared spectroscopy; Proteins; Water; graphene plasmons; Graphite; biosensing; Surface Plasmon Resonance; ta216; 01 natural sciences; 0104 chemical sciences

AbstractIdentifying 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.