Graphene Plasmon-Enhanced IR Biosensing for in Situ Detection of Aqueous-Phase Molecules with an Attenuated Total Reflection Mode.

Graphene plasmon has attracted extensive interest due to the unprecedented electromagnetic confinement, long propagation distance, and tunable plasmonic frequency. Successful applications of graphene plasmon as infrared sensors have been recently demonstrated, yet they are mainly focused on solid/solid and solid/gas interfaces analysis. Herein, we, for the first time, propose a graphene plasmon-enhanced infrared sensor based on attenuated total reflection configuration for in situ analysis of aqueous-phase molecules. This IR sensor includes a boron-doped graphene (BG) nanodisk array fabricated on top of a ZnSe prism surface that supports attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRA). Our ATR-SEIRA platform is efficient and straightforward for in situ and label-free monitoring of the interaction of biomolecules without interference from the environments, allowing for the extraction of instant spectroscopic information in a complex biological event. Utilizing the near-field enhancement of graphene plasmon, the binding interaction of L-selectin with its aptamer as a demonstration has been investigated to evaluate the specific protein recognition process. The detection limit of the target protein reaches 0.5 nM. Our work demonstrates that chemical-doped graphene plasmon combined with ATR-SEIRA is a promising signal enhancement platform for in situ aqueous-phase biosensing.