Hierarchically Assembled Plasmonic Metal-Dielectric-Metal Hybrid Nano-Architectures for High-Sensitivity SERS Detection

Abstract

In this work, we designed and prepared a hierarchically assembled 3D plasmonic metal-dielectric-metal (PMDM) hybrid nano-architecture for high-performance surface-enhanced Raman scattering (SERS) sensing. The fabrication of the PMDM hybrid nanostructure was achieved by the thermal evaporation of Au film followed by thermal dewetting and the atomic layer deposition (ALD) of the Al2O3 dielectric layer, which is crucial for creating numerous nanogaps between the core Au and the out-layered Au nanoparticles (NPs). The PMDM hybrid nanostructures exhibited strong SERS signals originating from highly enhanced electromagnetic (EM) hot spots at the 3 nm Al2O3 layer serving as the nanogap spacer, as confirmed by the finite-difference time-domain (FDTD) simulation. The PMDM SERS substrate achieved an outstanding SERS performance, including a high sensitivity (enhancement factor, EF of 1.3 × 108 and low detection limit 10−11 M) and excellent reproducibility (relative standard deviation (RSD) < 7.5%) for rhodamine 6G (R6G). This study opens a promising route for constructing multilayered plasmonic structures with abundant EM hotspots for the highly sensitive, rapid, and reproducible detection of biomolecules.

Picosecond Bessel Beam Fabricated Pure, Gold-Coated Silver Nanostructures for Trace-Level Sensing of Multiple Explosives and Hazardous Molecules

“…Thus far, various interesting laser-based spectroscopic techniques, including SERS [57,58], have been surveyed to accomplish the purpose of analytes detection, especially explosives. In recent times SERS has emerged as one of the fastest-growing research topics [59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74], offering fantastic advantages in real-time applications. Surface plasmon resonances in the nano regime, instigating the development of enormous evanescent fields, remain the origin of SERS.…”

Flexible Substrate of Cellulose Fiber/Structured Plasmonic Silver Nanoparticles Applied for Label-Free SERS Detection of Malathion

“…The electromagnetic mechanism is based on the local field enhancement of plasmonic nanostructures, which usually have a broad spectral band resulting in nonlinear scaling of Raman intensity [ 4 ]. It is worth noting that, in the case of the coincidence of optical excitation with a localized surface plasmon resonance for special nanostructures and configurations, so-called “hot spots” are formed, which can lead to SERS enhancement up to 10 8 or more [ 5 , 6 , 7 ]. In contrast, the chemical-enhancement effect provided by the charge transfer mechanism between the substrate and the analyte is generally much smaller and estimated to be in the range of 10–10 3 [ 8 ].…”

Three-Dimensional Dendritic Au–Ag Substrate for On-Site SERS Detection of Trace Molecules in Liquid Phase

“…Surface-enhanced Raman scattering (SERS) has been emerging as a powerful spectroscopic technique due to its extremely high sensitivity, fingerprint character and rapid nondestructive detection of molecules at an ultralow concentration [1][2][3][4][5]. In general, local surface plasmon resonance preferentially occurs in the nanoscale gaps between metal nanostructures [6][7][8]. Due to the improved signal feedback generated by the electromagnetic enhancement effect and practical requirements, SERS technology exploration further focuses on how to construct the active substrate with excellent performance and optimize its application.…”