Magnetic separation and SERS observation of analyte molecules on bifunctional silver/iron oxide composite nanostructures

Abstract

We report the preparation of bifunctional silver–iron oxide composite nanostructures (Ag@Fe2O3) and demonstrate their magnetic separation with an analyte molecule from silver nanoparticles in a mixed solution. Magnetic and non‐magnetic plasmonic nanostructures and their separation are monitored by the surface‐enhanced Raman scattering (SERS) spectra of two different analytes attached to each kind of particles. In general, such separation experiments can provide insight into basic phenomena of adsorption and exchange of adsorbed molecules which are of strong interest in SERS. The formation of stable Ag@Fe2O3 nanoparticle–molecule complexes suggests small magnetic SERS labels without additional protective layers for application in analytical assays. The magnetic plasmonic nanostructures have great promise for targeted imaging and sensing in biological structures by directing nanosensors to places of interest using magnetic fields. The option of magnetic separation and collection of plasmonic particles improves the analytical capabilities of SERS. Copyright © 2012 John Wiley & Sons, Ltd.

Semiconductor materials in analytical applications of surface‐enhanced Raman scattering

“…The discussion in this section will center on new efforts in the fabrication and application of metal/semiconductor heterostructures. In addition, the core–shell structured magnetic nanostructures are in principle excluded from this review because these works generally emphasize the magnetic separation and enrichment of targets, rather than the semiconductor‐mediated effect for SERS . In fact, we believe that the magnetic core may have some contribution to SERS, but it is difficult to identify at the present stage.…”

“…In fact, we believe that the magnetic core may have some contribution to SERS, but it is difficult to identify at the present stage. On the other hand, this is a subject treated in many articles, and we will not repeat here the detailed accounts given in the specialized literature …”

“…On the other hand, this is a subject treated in many articles, and we will not repeat here the detailed accounts given in the specialized literature. [75][76][77][78]…”

Magnetically Assembled SERS Substrates Composed of Iron–Silver Nanoparticles Obtained by Laser Ablation in Liquid

“…[1,6,14,15] On the other hand, transition metals, such as iron, are of limited interest for SERS, [14][15][16][17][18] due to the absence of plasmon resonance in the visible region and instability in air,b ut their magnetic properties find multiple analytical applications, for instance, in the realization of responsive nanotools for the separation of analytes in complex mixtures. [24,25] For instance,m ultiple analytes,s uch as viral biomarkers, [26,27] dopamine, [28] melamine, [29,30] arylthiols, [31] aromatic pollutants, [32] toxic molecules, [33,34] or targeted cells, [35] have been separated and detected by SERS with magnetic-plasmonic substrates. [24,25] For instance,m ultiple analytes,s uch as viral biomarkers, [26,27] dopamine, [28] melamine, [29,30] arylthiols, [31] aromatic pollutants, [32] toxic molecules, [33,34] or targeted cells, [35] have been separated and detected by SERS with magnetic-plasmonic substrates.…”

“…On the other hand, the application of externalm agnetic fields can be used to direct the assembly of magnetic-plasmonic NPs into arrays of SERS substrates. [41][42][43] All of these studies concerned hybrid structures composed of magnetic NPs with an oble-metalm oiety,s uch as heterostructures [27,28,31,35,42] or core-shells, [26,30,38,40,41,[44][45][46][47][48][49][50] whichr equire multiphase synthesis. To this aim, the exploitation of iron-doped silver nanoparticles (NPs) synthesized by laser ablation of abulk bimetallic iron-silver target immersedi ne thanol is described.…”