Role of Graphene in Constructing Multilayer Plasmonic SERS Substrate with Graphene/AgNPs as Chemical Mechanism—Electromagnetic Mechanism Unit

Abstract

Graphene–metal substrates have received widespread attention due to their superior surface-enhanced Raman scattering (SERS) performance. The strong coupling between graphene and metal particles can greatly improve the SERS performance and thus broaden the application fields. The way in which to make full use of the synergistic effect of the hybrid is still a key issue to improve SERS activity and stability. Here, we used graphene as a chemical mechanism (CM) layer and Ag nanoparticles (AgNPs) as an electromagnetic mechanism (EM) layer, forming a CM–EM unit and constructing a multi-layer hybrid structure as a SERS substrate. The improved SERS performance of the multilayer nanostructure was investigated experimentally and in theory. We demonstrated that the Raman enhancement effect increased as the number of CM–EM units increased, remaining nearly unchanged when the CM–EM unit was more than four. The limit of detection was down to 10−14 M for rhodamine 6G (R6G) and 10−12 M for crystal violet (CV), which confirmed the ultrahigh sensitivity of the multilayer SERS substrate. Furthermore, we investigated the reproducibility and thermal stability of the proposed multilayer SERS substrate. On the basis of these promising results, the development of new materials and novel methods for high performance sensing and biosensing applications will be promoted.

Orthogonal Surface‐Enhanced Raman Scattering/Field‐Effect Transistor Detection of Breast and Colorectal Cancer‐Derived Exosomes using Graphene as a Tag‐Free Diagnostic Template

“…Raman spectroscopic characterization of the same dyes on the GFET chip array (without electrical stimulation) followed with the results exhibited in Figure 3f,g. There was only minor enhancement of the Raman spectra for the reported dyes by the monolayer graphene substrate, though characteristic Raman peaks for the dyes were measured, namely, the peaks located at ≈1300 and 1450 cm −1 attributed to R6G (1 n m ), [ 39 ] whereas the D, G, and 2D graphene peaks were observed at ≈1380, ≈1600, and ≈2650 cm −1 , respectively. The intensity of these peaks generally increases with the concentration of the dyes for CV and R6G, with the latter exhibiting a better staircase profile for the variation of the peak intensity (Δ I ) with concentration, as shown in Figure 3h, for the G and 2D peaks (on average) relative to the control solution of phosphate‐buffered saline (PBS).…”

Ultrafast laser-induced decomposition for selective activation of GaAs

“…This result aligns with the concept that a thicker layer of plasmonic metal corresponds to a proportionally stronger SERS signal, with an enhancement factor of up to 108. [39][40][41] Both surface roughness and nanointerstices play pivotal roles in augmenting the local electric field of light, contributing to the enhancement observed in the SERS response. Even though the single smooth crystal nanobelt exhibited slightly lower SERS performance compared with the nanoplates, it still achieved a commendable detection sensitivity of 10 −7 mol/L.…”

Reproducible fabrication of gold nanostar monolayers for surface‐enhanced Raman spectroscopy‐based trace detection

“…Because of their distinct Raman spectrum and large cross section, they are often used as standards to test the detection sensitivity of SERS substrates. [43,44] Herein, we prepared a batch of aqueous solutions of CV, R6G, and RhB with different concentrations to test the performance of Au NSs SAM in trace detection. It is worth to note that, in some previous studies, the analyte solutions were dropped on the SERS substrate and SERS signals were detected after sample drying.…”