Composite substrate of graphene/Ag nanoparticles coupled with a multilayer film for surface-enhanced Raman scattering biosensing.

ABSTRACT

In this paper, we designed a surface-enhanced Raman scattering (SERS) substrate for graphene/Ag nanoparticles (Ag NPs) bonded multilayer film (MLF) using the hybrid nanostructures composed of graphene and plasmonic metal components with significant plasmonic electrical effects and unique optical characteristics. This paper achieved the advantages of efficient utilization of electromagnetic field and reduction of fluorescence background based on the electromagnetic enhancement activity of Ag NPs and unique physical/chemical properties of graphene with zero gap structures. Au/Al2O3 was stacked periodically to construct MLF. As indicated by the electric field intensity at the Au/Al2O3 interface of the respective layer, bulk plasmon polariton (BPP) in the MLF was excited and coupled with localized surface plasmon (LSP) in the Ag NPs, which enhanced the electromagnetic field on the top-layer of SERS substrate. To measure the performance of the SERS substrate, rhodamine 6G (R6G) and malachite green (MG) were used as the probe molecules, with the detection limits of 10-11 M and 10-8 M, respectively. The SERS substrate had high sensitivity and uniformity, which indicated that it has a broad application prospect in the field of molecular detection.