TiO2/Ag nanostructured coatings as recyclable platforms for surface-enhanced Raman scattering detection
Abstract
The surface-enhanced Raman scattering (SERS) has become irreplaceable for the direct detection of organic chemicals and biomolecules. However, the SERS-active platforms need to meet certain requirements for routine use.
Among them, the most important are low detection limit, spectra reproducibility, and the possibility of being re-used. In this study, we investigate and compare the SERS performance of Ag/TiO2 coatings with three different architectures -planar, tubular and nanoparticle-based - prepared by means of plasma-assisted techniques.
In all three cases, the nanoislands, made of plasmonic Ag, enhance the SERS signal, while the TiO2 provides degra-dation of surface contaminants after UV irradiation. The latter relates to the natural photoactivity of titania, which enables the recycling of the substrates.
As shown, nanopatterning of surfaces offers a good compromise between the high detection limit and re-cyclability of those nanostructured Ag/TiO2 coatings with larger active surface area; here, namely TiO2 nanoparticle films decorated with silver nanoislands behave promisingly. Such nanostructured Ag/TiO2 films allow not only the detection of methylene blue (MB) at concentrations down to 5 x 10-9 M, but also may be easily cleaned by UV radiation in a reasonable time scale.