Off-Resonance Gold Nanobone Films at Liquid Interface for SERS Applications

Area of Science:

• Nanotechnology
• Spectroscopy
• Analytical Chemistry

Background:

• Surface-Enhanced Raman Spectroscopy (SERS) shows great potential for trace analyte detection.
• The debate continues regarding whether on-resonance plasmonic nanostructures yield stronger SERS enhancements than off-resonance ones.

Purpose of the Study:

• To compare the SERS performance of off-resonance gold nanobones (GNBs) with on-resonance GNBs and gold nanorods (GNRs).
• To evaluate nanostructures in both colloidal dispersion and self-assembled films at a liquid-liquid interface.
• To determine the optimal substrate configuration for sensitive trace detection.

Main Methods:

• Utilized gold nanobones (GNBs) and gold nanorods (GNRs) as plasmonic nanostructures.
• Investigated both colloidal dispersions and close-packed films assembled at a liquid-liquid interface.
• Employed Rhodamine 6G (R6G) as a Raman reporter to assess SERS efficacy.

Main Results:

• Nanostructures assembled at liquid interfaces showed 17- to 55-fold signal enhancement compared to colloidal dispersions.
• Off-resonance GNBs consistently outperformed on-resonance nanostructures in SERS signal generation.
• Off-resonance GNBs at the liquid interface achieved a limit of detection (LOD) of 5 × 10^-9 M for R6G.

Conclusions:

• Off-resonance GNBs assembled at liquid interfaces are highly effective SERS substrates.
• The findings challenge the prevailing belief that on-resonance conditions are always superior for SERS.
• This optimized substrate configuration demonstrates suitability for sensitive analytical applications.