Au Nanocucumbers with Interior Nanogap for Multiple Laser Wavelength‐Compatible Surface‐Enhanced Raman Scattering#

Abstract

It is critical to design and synthesize plasmonic nanostructures that can generate very strong and quantitative surface‐enhanced Raman scattering (SERS) signals that could be amplified by multiple laser wavelengths to realize the full potential of SERS nanoprobes. Here, we report the synthesis of Au‐nanobridged nanogap cucumbers (Au‐NNCs) from DNA‐modified Au nanorods and comparison of their SERS signals with three different Raman dyes with our recently reported Au‐nanobridged nanogap spheres (Au‐NNSs). Although the Au‐NNSs generate highly stable and reliable signals, these spherical nanogap structures with a smooth surface produce strong SERS signals (SERS enhancement factor at ~108) only with 633 nm excitation laser. The Au‐NNCs with a bumpy surface generated up to ~3‐, ~23‐, and ~130‐fold higher SERS signals with 514, 633, and 785 nm excitation laser wavelengths, respectively, compared to the Au‐NNSs.