In vitro study on the competitive reactions between arsenite and selenite with glutathione.

Exposure to arsenic can cause various biological effects by increasing the production of reactive oxygen species (ROS). Selenium acts as a beneficial element by regulating ROS and limiting heavy metal uptake and translocation. There are studies on the interactive effects of As and Se in plants, but the antagonistic and synergistic effects of these elements based on their binding to glutathione (GSH) molecules have not been studied yet.

Evaluation of colloidal platinum on cytotoxicity, oxidative stress and barrier permeability across the gut epithelium.

Colloidal platinum (Pt) is widely consumed due to its health promoting benefits. However, the exact biological effects of these nanoparticles have not been studied in detail, particularly in the gut. In the present study we observed that colloidal Pt was not cytotoxic towards three different epithelial colon cancer cell lines.

'Fairy Chimney'-shaped tandem metamaterials as double resonance SERS substrates.

A highly tunable design for obtaining double resonance substrates to be used in surface-enhanced Raman spectroscopy is proposed. Tandem truncated nanocones composed of Au-SiO(2)-Au layers are designed, simulated and fabricated to obtain resonances at laser excitation and Stokes frequencies. Surface-enhanced Raman scattering experiments are conducted to compare the enhancements obtained from double resonance substrates to those obtained from single resonance gold truncated nanocones.

Tunable surface plasmon resonance on an elastomeric substrate.

In this study, we demonstrate that periods of metallic gratings on elastomeric substrates can be tuned with external strain and hence are found to control the resonance condition of surface plasmon polaritons. We have excited the plasmon resonance on the elastomeric grating coated with gold and silver. The grating period is increased up to 25% by applying an external mechanical strain.

Plasmonic band gap structures for surface-enhanced Raman scattering.

Surface-enhanced Raman Scattering (SERS) of rhodamine 6G (R6G) adsorbed on biharmonic metallic grating structures was studied. Biharmonic metallic gratings include two different grating components, one acting as a coupler to excite surface plasmon polaritons (SPP), and the other forming a plasmonic band gap for the propagating SPPs. In the vicinity of the band edges, localized surface plasmons are formed.

Effect of solvent refractive index on the surface plasmon resonance nanoparticle optical absorption.

Optical properties of plasmon coupled silver and gold nanoparticles were studied as a function of the refractive index of the surrounding medium. Our studies confirmed that the effect of changes in the refractive index of the surrounding medium was more difficult to demonstrate from an experimental point of view, because of the very high susceptibility of nanoparticles to aggregate in aqueous and organic solvents. Whereas the position of the absorption bands of triiodide in these solvents shows a clear dependence on medium's refractive index, the surface plasmon band position of silver and gold nanoparticles do not exhibit the same dependence.

Electrothermal atomic absorption spectrometric determination of gold by vapor formation and in situ trapping in graphite tubes.

Gold was determined in ore samples following generation, separation, collection on a graphite cuvette inner wall, and atomization of its volatile species formed by combining an acidified sample solution with an aqueous sodium tetrahydroborate solution at room temperature. A detection limit of 2.6 microg L(-1) (3sigma) was obtained with a 5.

Differentiation of domains in composite surface structures by charge-contrast X-ray photoelectron spectroscopy.

An external bias is applied to two samples containing composite surface structures, while recording an XPS spectrum. Altering the polarity of the bias affects the extent of differential charging in domains that are chemically or electronically different to create a charge contrast. By utilizing this charge contrast, we show that two distinct silicon nitride and silicon oxynitride domains are present in one of the composite samples.

Interference effect of iron on the determination of gold in geological samples using the vapor generation technique and preconcentration in a graphite furnace.

A vapor generation procedure for the production of volatile species of Au was studied using electrothermal atomic absorption spectrometry (ETAAS). The interference effects of iron in solution and in the gas phase in a quartz T-tube were studied for the first time in detail. A dual vapor generation system was used for a single heated quartz tube atomizer, so that it was possible to study interferences and classify them regarding their origins.

X-ray-induced production of gold nanoparticles on a SiO(2)/Si system and in a poly(methyl methacrylate) matrix.

Prolonged exposure to X-rays of HAuCl(4) deposited from an aqueous solution onto a SiO(2)/Si substrate or into a poly(methyl methacrylate) (PMMA) matrix induces reduction of the Au(3+) ions to Au(0) and subsequent nucleation to gold nanoclusters as recorded by X-ray photoelectron spectroscopy. The corresponding major oxidation product is determined as chlorine {HAuCl(4)(ads) + X-rays --> Au(ads) + (3/2)Cl(2)(ads) + HCl(ads)}, which is initially adsorbed onto the surface but eventually diffuses out of the system into the vacuum. The reduced gold atoms aggregate (three-dimensionally) into gold nanoclusters as evidenced by the variation in the binding energy during X-ray exposure, which starts as 1.