Continuously Tunable Localized Surface Plasmon Resonance of Anisotropic Gold Nanopolyhedrons for Multiplexed Surface-Enhanced Raman Scattering Imaging

Abstract

Abstract Surface-enhanced Raman scattering (SERS) is attractive for multiplex bioimaging owing to its excellent photostability and ultranarrow spectral bandwidth. However, achieving synergistic enhancement of excitation and Raman scattering fields remains challenging. Herein, the relationship between geometry and localized surface plasmon resonance (LSPR) was investigated by continuously tuning the aspect ratio (AR) of anisotropic Au nanopolyhedrons (Au NPHs). Central-body modulation while preserving sharp terminal tips enables continuous LSPR tuning while retaining tip-associated electromagnetic enhancement. The SERS behavior was further analyzed by considering the spectral matching between the LSPR and the excitation/scattering wavelengths. For different excitation wavelengths, the optimal SERS response can be achieved by selecting Au NPHs whose LSPR band best matches with the excitation and Raman scattering wavelengths. These results demonstrate that Raman enhancement is governed by spectral matching rather than a fixed optimal geometry. The optimized Au NPHs enabled the use of dual SERS probes for proof-of-concept multiplex biomarker imaging.