Ag@TiO nanogranular films by gas phase synthesis as hybrid SERS platforms.

The synthesis of hybrid metallic-dielectric substrates as reliable SERS platforms relies on core-shell nanoparticles, obtained by wet chemistry, with an outer dielectric shell composed of SiO or TiO. Apart from the shell composition, the nanoparticle density and aggregation type strongly affect the surface-enhanced SERS. Going beyond a single layer by building random aggregates of hybrid NPs would result in a step forward in the production of reliable hybrid SERS platforms.

Photo-induced heat generation in non-plasmonic nanoantennas.

Light-to-heat conversion in non-plasmonic, high refractive index nanoantennas is a key topic for many applications, including Raman sensing, laser writing, nanofabrication and photo-thermal therapy. However, heat generation and propagation in non-plasmonic antennas is increasingly debated and contradictory results have been reported so far. Here we report a finite element analysis of the steady-state temperature distribution and heat flow in SiO2/Si core/shell systems (silicon nanoshells) irradiated with different continuous wave lasers (λ = 532, 633 and 785 nm), under real working conditions.

Non-Plasmonic SERS with Silicon: Is It Really Safe? New Insights into the Optothermal Properties of Core/Shell Microbeads.

Silicon is one of the most interesting candidates for plasmon-free surface-enhaced Raman scattering (SERS), because of its high-refractive index and thermal stability. However, here we demonstrate that the alleged thermal stability of silicon nanoshells irradiated by conventional Raman laser cannot be taken for granted. We investigated the opto-thermal behavior of SiO/Si core/shell microbeads (Si-rex) irradiated with three common Raman laser sources (λ = 532, 633, 785 nm) under real working conditions.

Highly sensitive biosensors based on all-dielectric nanoresonators.

Biosensing based on nanophotonic structures has shown a great potential for cost-efficient, high-speed and compact personal medical diagnostics. While plasmonic nanosensors offer high sensitivity, their intrinsically restricted resonance quality factors and strong heating due to metal absorption impose severe limitations on real life applications. Here, we demonstrate an all-dielectric sensing platform based on silicon nanodisks with strong optically-induced magnetic resonances, which are able to detect a concentration of streptavidin of as low as 10 M (mol L) or 5 ng mL, thus pushing the current detection limit by at least two orders of magnitudes.

"RaMassays": Synergistic Enhancement of Plasmon-Free Raman Scattering and Mass Spectrometry for Multimodal Analysis of Small Molecules.

SiO/TiO core/shell (T-rex) beads were exploited as "all-in-one" building-block materials to create analytical assays that combine plasmon-free surface enhanced Raman scattering (SERS) and surface assisted laser desorption/ionization (SALDI) mass spectrometry (RaMassays). Such a multi-modal approach relies on the unique optical properties of T-rex beads, which are able to harvest and manage light in both UV and Vis range, making ionization and Raman scattering more efficient. RaMassays were successfully applied to the detection of small (molecular weight, M.

Plasmon-free SERS detection of environmental CO2 on TiO2 surfaces.

SiO2/TiO2 core/shell beads (T-rex) were designed, fabricated and tested for Raman detection of environmental CO2 under real-working conditions, as those encountered, for example, in solar-to-fuel conversion reactions. The exploitation of light trapping and morphology dependent resonances was crucial for extending the limit of detection of CO2 adsorbed on TiO2 surfaces. T-rex beads allowed for achieving surface enhanced Raman scattering (SERS) without using plasmonic metals showing high-efficiency, fast response and reproducibility in CO2 detection in both air and solvents.

Probing the spatial extension of light trapping-induced enhanced Raman scattering in high-density Si nanowire arrays.

This paper reports an experimental investigation of surface-enhanced Raman scattering in high-density Si nanowire arrays obtained by electroless etching. A direct relationship between light trapping capabilities of Si nanowires and enhanced Raman scattering was demonstrated. Optimized arrays allowed for a remarkable increase of Raman sensitivity in comparison to reference planar samples.