SERS under magnetic control

Magnetic tuning of SERS hot spots in polymer-coated magnetic–plasmonic iron–silver nanoparticles

“…20 To date, hot spot tuning has been achieved in different ways: by supporting plasmonic NPs in elastic substrates which can be mechanically deformed to change the interparticle distance; 21 by using thermosensitive or pH responsive matrixes; 22,23 by using focused laser beams in a uid matrix to optically pinch and manipulate the NPs; 24 by chemical transformation of metal NPs in arrays by growing or shrinking their size; 3,25 and by using a magnetic eld in magnetic-plasmonic nanostructures. [26][27][28] In particular, the nal approach has been considered frequently, due to the various magnetic-plasmonic nanostructures proposed in the literature, such as nanoshells with a magnetic core coated with a noble metal shell, [29][30][31] core-satellite NPs, 18,20,[32][33][34][35] dumbbells or heterostructures made of magnetic and plasmonic components, 36 and dielectric matrixes embedding mixtures of noble metals and iron oxides. 19 Another advantage of magnetic-plasmonic NPs is the possibility to control their position in the liquid phase as well as on a substrate, by removal of the dispersing liquid aer magnetic assembly.…”

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

“…[36,51] However,our experiments showed that light scattering and absorption in the plasmonic spot could be detrimental to SERS analysis, if ac ritical NP concentration threshold was exceeded in the solution depositedfor the magnetic assembly. In this way,w eo bserved a2 8-foldi ncrement of the SERS signal collectedf rom the plasmonic spots, relative to the same NPs spotted on the glass slide without magnetic assembly or to ar eference of nonmagnetic pure Ag NPs.…”

“…The increment in SERS signal is due to increased scattering of light in the plasmonic substrate and to ah igherc oncentration of electromagnetic hot spots in the magnetically induced aggregates. [36,51] However,our experiments showed that light scattering and absorption in the plasmonic spot could be detrimental to SERS analysis, if ac ritical NP concentration threshold was exceeded in the solution depositedfor the magnetic assembly.…”

“…[19][20][21][22][23] Hence, as ingle nanostructure with the plasmonic responseo fs ilver and the magnetic properties of iron is exploitable as ap owerful SERS substrate that can be manipulated and controlled by externalm agnetic fields. [36] Interestingly,t heses ubstrates are achievable in ar eproducible ands calable way,a llowing the preparation of arrays of variable dimensions (varying the The widespreada pplication of surface-enhanced Raman scattering (SERS) would benefit from simple and scalable self-assembly procedures for the realization of plasmonic arrays with ah igh density of electromagnetic hot-spots. 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.…”

“…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. [36] Interestingly,t heses ubstrates are achievable in ar eproducible ands calable way,a llowing the preparation of arrays of variable dimensions (varying the The widespreada pplication of surface-enhanced Raman scattering (SERS) would benefit from simple and scalable self-assembly procedures for the realization of plasmonic arrays with ah igh density of electromagnetic hot-spots. 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.…”