Surface enhanced Raman scattering by graphene-nanosheet-gapped plasmonic nanoparticle arrays for multiplexed DNA detection

Abstract

We have developed a new type of surface enhanced Raman scattering (SERS) substrate with thiolated graphene oxide (tGO) nanosheets sandwiched between two layers of closely packed plasmonic nanoparticles. The trilayered substrate is built up through alternative loading of interfacially assembled plasmonic nanoparticle arrays and tGO nanosheets, followed by coating the nanoparticle surfaces with poly(ethylene glycol) (PEG). Here tGO plays multifunctional roles as a 2D scaffold to immobilized interfacially assembled plasmonic nanoparticles, a nanospacer to create SERS-active nanogaps between two layers of nanoparticle arrays, and a molecule harvester to enrich molecules of interest viaπ-π interaction. In particular, the molecule harvesting capability of the tGO nanospacer and the stealth properties of PEG coating on the plasmonic nanoparticles collectively lead to preferential positioning of selective targets such as aromatic molecules and single-stranded DNA at the SERS-active nanogap hotspots. We have demonstrated that an SERS assay based on the PEGylated trilayered substrate, in combination with magnetic separation, allows for sensitive, multiplexed "signal-off" detection of DNA sequences of bacterial pathogens.

Hybrid nanostructures of metal/two-dimensional nanomaterials for plasmon-enhanced applications

“…77 Recently, a sandwiched metal NP/graphene/metal film hybrid system has received increased attention due to its promise of being used in SERS applications. 284,297,303,[353][354][355][356] As shown in Fig. 14(a), the sandwiched hybrid structure is composed of Ag NPs with a diameter of 20 nm residing on an ultrathin graphene spacer layer covering an Ag film.…”

Surface Enhanced Raman Spectroscopy for DNA Biosensors—How Far Are We?

“…Briefly, thiolated single-stranded DNA with a specific sequence is attached to plasmonic nanoparticles or plasmonic and magnetic nanoparticles [43][44][45][46][47][48][49][50]. Due to hybridization, in the presence of the target DNA, nanoparticles form agglomerates (Figure 3), which can be easily detected from the increase in the intensity of the measured SERS signal in the case of plasmonic agglomerates (the SERS enhancement factor is especially large for species located in the narrow slit between plasmonic structures), or from the formation of the plasmonic-magnetic agglomerates, which can concentrate by the magnetic field [51]. The formation of the agglomerates indicates the presence of the target DNA.…”

Advances in Medical Wearable Biosensors: Design, Fabrication and Materials Strategies in Healthcare Monitoring

“…Duan et al (2015) developed a multilayered PEGylated (PEG: polyethylene glycol) nanosheet for multiplexed DNA detection, in particular for bacterial pathogens. Even with the wide range of research available on graphene-based sensors [ 118 ], there is still a long way ahead before they can be popularly integrated into day-to-day life, given the complexity, cost, and optimization required. Nonetheless, graphene-based materials offer high-quality sensing, which is worth the investment in terms of time, money, and resources.…”