Remote plasmonic-enhanced Raman spectroscopy with the plasmon-molecule coupling in distance over 100 nm

¹ Institute of Post-LED Photonics, Tokushima University, Tokushima 770-8506, Japan
² Technology & Engineering Division, Ushio Inc., Hyogo 671-0224, Japan.
³ The Institute of Science and Industrial Research, Osaka University, Osaka 567-0047, Japan.
⁴ Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.

^* Corresponding author: minamikawa.takeo@tokushima-u.ac.jp

Published online: 18 October 2023

Abstract

We propose remote plasmonic-enhanced Raman scattering (RPERS) spectroscopy for molecular sensing and imaging applications. RPERS requires no contact between analyte molecules and metallic nanostructures, which overcomes the limitations of surface-enhanced Raman scattering (SERS). We constructed RPERS substrates consisting of silver nanoislands and columnar silica structures, which demonstrated a 2×10⁷ enhancement in Raman scattering for Rhodamine 6G molecules, even when the metal nanostructures and analyte molecules were over 100 nm apart. The RPERS substrate also exhibited improved reproducibility (<15% RSD), long-term stability (>1 month), and sensitivity (>10 times) compared to conventional SERS substrates. We also confirmed the feasibility of RPERS for biophotonic analysis, i.e., enhancing Raman histological imaging of oesophagus tissues with oesophageal adventitia of a Wistar rat attached atop the columnar silica structure layer. Our demonstration is a promising advancement in the field of enhanced spectroscopy using plasmon and offers a solution to the challenges faced by conventional SERS spectroscopy. It has the potential to pave the way for future developments in remote plasmonic-enhanced spectroscopy.