Direct and one-step synthesis of polythiophene/gold nanoparticles thin films through liquid/liquid interfacial polymerization.

This work demonstrates a simple and one-step synthesis of polythiophene/gold nanoparticles (PT/Au) nanocomposite thin films, through a liquid-liquid (L/L) interfacial polymerization route. Starting from an aqueous solution of tetrachloroauric acid (acting both as metallic gold source and oxidizing agent to start the oxidative polymerization of thiophene), and a solution of thiophene in n-hexane, a biphasic L/L system was originated. In the following, the interface acted as a meeting-point for the reactants, and the polymerization reaction took place, leading to self-assembled PT/Au film between the two immiscible liquids.

Matching long-period grating modes and localized plasmon resonances: effect on the sensitivity of the grating to the surrounding refractive index.

The sensitivity and dynamical range of an optical-fiber transducer consisting of a long-period grating coated with gold nanoparticles is investigated. For a grating with an 80 μm spatial periodicity, the resonances close to the turning point lie within the 450-900 nm spectral range. Employing a bottom-up production route, the localized surface plasmon resonance of gold nanoparticles is matched to the grating resonances; it is shown that this results in an increase in the refractive index sensitivity of the device.

Plasmonic optical fiber sensors: enhanced sensitivity in water-based environments.

In this work, we demonstrate a refractometric fiber sensor with improved sensitivity for refractive indices ranging from 1.3629 to 1.4479.

Thin and transparent films of graphene/silver nanoparticles obtained at liquid-liquid interfaces: preparation, characterization and application as SERS substrates.

We report here the synthesis and characterization of transparent and homogeneous thin films of reduced graphene oxide/silver nanoparticles (rGO/AgNPs) nanocomposites, starting from graphene oxide (GO) or reduced graphene oxide (rGO), directly obtained at a water/toluene liquid-liquid interface. Different films (obtained by varying the Ag/rGO or Ag/GO ratio) were prepared, deposited over glass or plastic substrates, and characterized by X-ray diffraction, UV-Vis and Raman spectroscopy, thermal analysis, transmission and scanning electron microscopy. Samples were evaluated as substrates for surface-enhanced Raman spectroscopy (SERS), using dilute solutions (1×10(-7) mol L(-1)) of a common probe molecule, 4-aminothiophenol (4-ATP).