Ultrasensitive and Remote SERS Enabled by Oxygen-free Integrated Plasmonic Field Transmission

Single-molecule surface enhanced Raman spectroscopy (SERS) is a sensitive technique for detecting low concentrations of adsorbed analytes on plasmonic nanosurfaces. Here, we observe that scavenging dissolved oxygen can further increase its sensitivity 109–1010 times, enabling real single-molecule detection—in other words, detecting 1 molecule in 300–500 μL aqueous solution. Experimental evidence and computational modeling support propagation of the plasmonic field throughout the entire sample volume, which enables analyte detection outside the instrument field of view. The application of readily available and inexpensive oxygen scavengers enables ultra-high analytical sensitivity using affordable instrumentation, greatly facilitating single-molecule-level research in both well-equipped and resource-limited laboratories. Furthermore, the discovery may bring fresh insights into the fundamental understanding of SERS and plasmonic field transmission in aqueous solutions.