Surface-enhanced raman scattering platforms on the basis of assembled gold nanorods

SERS substrates formed by gold nanorods deposited on colloidal silica films

“…The structure of such substrates is shown in Additional file 1: Figure S1. In particular, the fractal-like GNR assemblies were shown to have a maximum SERS enhancement in comparison with single-particle and densely packed monolayers [33]. For dilute GNR sols, the GNR assemblies demonstrated an island structure after deposition on a silicon wafer and drying in air (see, for example, Additional file 1: Figure S2).…”

“…This process was repeated several times to attain the desired surface and volume densities of the GNRs embedded in and deposited on the OPC film. For comparative purposes, we also fabricated SERS substrates by depositing GNR sols differing in concentration directly on plain silicon wafers as described previously in [33]. …”

“…Such GNR-OPC substrates combine the increased specific surface, owing to the multilayer nanosphere structure, and various spatial GNR configurations, including those with possible plasmonic hot spots [5,51]. We demonstrate here the existence of the optimal GNR deposition density for the maximal SERS effect, which turned out to be higher than that for the thick random GNR assemblies [33] formed directly on a plain silicon wafer.…”

“…The fabricated SERS substrate should ensure several key features [33,36]: (1) high SERS enhancement and sensitivity, (2) large-scale uniformity, with the integral SERS enhancement variations over the entire substrate surface being less than 10% to 20%, (3) high stability and reproducibility between fabrication runs, and (4) low fabrication costs.…”

“…One of the obvious advantages of plasmonic nanopowders is that they retain their plasmonic properties under usual conditions; they can be easily dispersed in water to obtain sols of the desired concentration in a matter of seconds without any sonication, heating, etc. In particular, we have already utilized GNR powders to fabricate monolayer and fractal-like plasmonic films for SERS applications [33]. However, these substrates demonstrated a moderate analytical enhancement [42] averaged over the probe laser beam spot.…”