Publications by authors named "Stephanie Lau-Truong"

Article Synopsis
  • * SLRs offer advantages like narrower bandwidths and enhanced electric fields compared to LSPs, which are essential for creating efficient optical devices, with grazing diffracted orders playing a key role in their properties.
  • * The study utilizes both experimental and theoretical methods, including simulations of gold disk arrays, to show that SLR characteristics are closely linked to the efficiency of diffracted modes, emphasizing the importance of inter-particle spacing for optimizing performance in photonic applications.
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Self-organized spatial patterns are increasingly recognized for their contribution to ecosystem functioning. They can improve the ecosystem's ability to respond to perturbation and thus increase its resilience to environmental stress. Plastic pollution has now emerged as major threat to aquatic and terrestrial biota.

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When assembled in periodic arrangements, metallic nanostructures (NSs) support plasmonic surface lattice (SL) resonances resulting from long-range interactions these surface lattice resonances differ radically from localized surface plasmon (LSP). Similarly to the hybridization of LSP resonances, observed in short-range interactions, we demonstrate the possibility to generate a hybridization of surface lattice (SL) plasmon resonances, by the excitation of grazing order diffraction within the metasurface. This hybridization leads to the emergence of and modes.

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Long-range interaction in regular metallic nanostructure arrays can provide the possibility to manipulate their optical properties, governed by the excitation of localized surface plasmon (LSP) resonances. When assembling the nanoparticles in an array, interactions between nanoparticles can result in a strong electromagnetic coupling for specific grating constants. Such a grating effect leads to narrow LSP peaks due to the emergence of new radiative orders in the plane of the substrate, and thus, an important improvement of the intensity of the local electric field.

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Localized surface plasmon resonance (LSPR) excitation on the photochromic reaction of a diarylethene derivative (DE) was studied by surface enhanced Raman scattering (SERS). UV and visible light irradiations transform reversibly DE between open-form (OF) and closed-form (CF) isomers, respectively. A mixture of PMMA and DE (either OF or CF isomer) was spin-coated onto gold nanorods (GNRs) arrays, designed by electron beam lithography, with two localized surface plasmon resonances (LSPR) at distinct wavelengths, due to their anisotropy.

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In this work, the preparation of magneto-plasmonic granular nanostructures and their evaluation as efficient substrates for magnetically assisted surface enhanced Raman spectroscopy (SERS) sensing are discussed. These nanostructures consist of star-shaped gold Au shell grown on iron oxide FeO multicores. They were prepared by seed-mediated growth of anisotropic, in shape gold nanosatellites attached to the surface of polyol-made iron oxide polycrystals.

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A common challenge in nanotechnology is the conception of materials with well-defined nanoscale structure. In recent years, virus capsids have been used as templates to create a network to organize 3D nano-objects, building thus new functional nanomaterials and then devices. In this work, we synthetized 3D gold nanoclusters and we used them as Surface Enhanced Raman Scattering (SERS) sensor substrates in solution.

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Site-selective surface functionalization of anisotropic gold nanoparticles represents a major breakthrough for fully exploiting nanoparticle anisotropy. In this paper, we explore an original strategy for the regioselective functionalization of lithographically designed gold nanorods (AuNRs), based a combination of photo-induced plasmon excitation and aryl diazonium salt chemistry.

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Article Synopsis
  • The study demonstrates that using oriented arrays of smectic A defects, termed smectic oily streaks, can effectively orient gold nanorods (GNRs) across a range of sizes and ligands.
  • It was found that increasing the density of small GNRs led to the formation of oriented end-to-end chains, revealing their alignment predominantly along the oily streaks.
  • The research also highlights the electromagnetic coupling of the GNRs, showing that their orientation influences their luminescence and interaction, which is further affected by van der Waals forces and steric repulsion between them.
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Tetrafluoroborate salts of diazotized Azure A (AA-N), Neutral Red (NR-N) and Congo Red (CR-N) dyes were prepared and reacted with multiwalled carbon nanotubes (MWCNTs) at room temperature, in water without any reducing agent. The as-modified MWCNTs were examined by IRATR, Raman spectroscopy, XPS, TGA, TEM, and cyclic voltammetry. The diazonium band located at ∼2350 cm in the diazotized dye IR spectra vanished after attachment to the nanotubes whereas the Raman D/G peak ratio slightly increased after dye covalent attachment at a high initial diazonium/CNT mass ratio.

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The controlled assembly of anisotropic plasmonic nanoparticles (NPs) into highly SERS-active substrates remains particularly challenging for the production of long-term stable NP assemblies in suspension. In this work, we report a simple and efficient strategy to assemble gold nanorods (AuNRs) into dimers. The pH-dependent assembly was triggered using the bifunctional molecular linker BPE (1,2-bis(4-pyridyl)ethylene) and quenched with silver nitrate.

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A smart and highly SERS-active plasmonic platform was designed by coupling regular arrays of nanotriangles to colloidal gold nanorods via a thermoresponsive polymer spacer (poly(N-isopropylacrylamide), PNIPAM). The substrates were prepared by combining a top-down and a bottom-up approach based on nanosphere lithography, surface-initiated controlled radical polymerization, and colloidal assembly. This multistep strategy provided regular hexagonal arrays of nanotriangles functionalized by polymer brushes and colloidal gold nanorods, confined exclusively on the nanotriangle surface.

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Article Synopsis
  • - This study introduces a new method for creating molecularly imprinted polymers around gold nanorods using diazonium salt chemistry combined with the iniferter technique.
  • - The approach allows for precise control over the imprinting process on a nanoscale, enhancing the effectiveness of the polymers.
  • - The resulting product is water-soluble plasmonic nanosensors, which could have various applications in sensing technologies.
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The chemisorption of 1,3,4-oxadiazole-2-thiol (ODT) on gold nanorods has been investigated by using surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT). Although most of the SERS spectra have remarkable similarity to the normal Raman spectra of the pure analyte, the adsorption of ODT on a gold surface leads to a drastic change in its Raman spectrum and distinct vibrational features are obtained with gold nanorods and spherical nanoparticles. Simulated Raman spectra for hybrid systems that consist of an oxadiazole moiety coordinated to a Au20 gold cluster provided valuable information about the coordination mode and enabled us to assign vibration modes.

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In this paper, we demonstrate the template-assisted deposition of cetyltrimethylammonium bromide (CTAB) stabilized gold nanorods at lithographically defined positions on a substrate. Overcoating of the nanoparticles with polystyrenesulfonate allows to switch the original nanoparticles positive surface charge to negative and to apply the template-assisted deposition technique developed for citrate-capped gold nanoparticles also to CTAB stabilized nanoparticles. The successful, selective deposition of gold nanorods in trenches with widths down to 50 nm is demonstrated.

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3D nanostructured transparent indium tin oxide (ITO) electrodes prepared by glancing angle deposition (GLAD) were used for the spectroelectrochemical characterization of cytochrome c (Cyt c) and neuroglobin (Nb). These small hemoproteins, involved as electron-transfer partners in the prevention of apoptosis, are oppositely charged at physiological pH and can each be adsorbed within the ITO network under different pH conditions. The resulting modified electrodes were investigated by UV-visible absorption spectroscopy coupled with cyclic voltammetry.

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