Monoclinic BiVO 4 powders have been synthesized by means of homogeneous coprecipitation, followed by calcination at different temperatures. The effect of the calcination temperature on the changes in the physicochemical parameters has been evaluated. It has been deduced that the crystallite size and band gap are responsible for water oxidation. The effect of calcination temperatures on the variations, such as lone pair distortions on Bi 3+ and changes in the V−O bond length in the local structure of BiVO 4 , has also been confirmed from the changes in the intensities and the shift of the peak position in the Raman analysis.

Ag nanoparticles synthesized on porous silicon samples were studied and applied as substrates for surface‐enhanced Raman scattering (SERS). The metallic nanostructures prepared by immersion plating were characterized by UV–Vis reflectance spectroscopy and scanning electron microscopy. SERS activity of the substrates was tested using Cyanine dye 1,3,3,1′,3′,3′‐esamethyl‐5,5′‐dimethoxyindodicarbocyanine iodide (Cy5‐OCH3) as a probe molecule. The Raman spectra obtained for different excitation wavelengths indicate amplifications ascribed to plasmonic resonances with an enhancement factor up to 107. CGIYRLRS peptides were chemisorbed on the Ag nanoparticles with the plasmonic resonance tuned at the excitation energy. Such oligopeptides were used as baits for a specific polyclonal antibody. The overall Raman enhancement allowed to evidence a good selectivity to the target analyte as required by most of the SERS applications on biological assays. Copyright © 2011 John Wiley & Sons, Ltd.

In this study, a novel SERS sensor has been developed for repeatable detection of organic molecules and biological assays. Vertically oriented titania nanotube (TiO 2 NT) arrays were grown by ultra-fast anodic oxidation of flexible titanium foils and then decorated with Ag nanoparticles (NPs) through d.c.sputtering deposition at room temperature. A parametric study was carried out taking into account the effect of sputtering parameters on the Ag NP arrangements on the NT surface. The structure morphology was investigated by means of scanning and transmission electron microscopy, evidencing the formation of hexagonal close-packed TiO 2 NTs coated with Ag nanoparticles showing tunable diameter and distribution. The substrates were employed in a SERS optofluidic device, consisting of a polydimethylsiloxane cover irreversibly sealed to the silver-coated TiO 2 NTs, able to detect Rhodamine molecules in ethanol over a wide range of concentrations down to 10 À14 M, taking advantage of both electromagnetic and chemical enhancements. In order to evaluate the performances of the SERS substrates in terms of biosensing, an optimized protocol for the immobilization of oligonucleotide probes on the metal-dielectric surfaces was developed for verifying the hybridization events.

Metal-dielectric nanostructures consisting of Ag nanoparticles synthesized within a mesoporous silicon matrix are exploited for single molecule detection by surface-enhanced resonance Raman scattering (SERRS). The morphology is controlled yielding plasmonic resonances in the visible-near-infrared range. Enhanced Raman activity of the substrates are tested using Cy3 and R6G dyes as probe molecules. Tuning the particle plasmonic resonance close to the molecule electronic resonance, we demonstrate Raman enhancements larger than 1010. Time resolved Raman spectroscopy at very low molecule concentration yields intensity fluctuations which can be mainly ascribed to a charge transfer-enhancement mediated by the molecules diffusion between different sites on Ag particles.

Stretchable plasmonic nanostructures constituted by Ag nanoparticles on flexible elastomeric matrices are synthesized and used as surface-enhanced Raman scattering (SERS) substrates.