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Gold NPs (gold + np)

Distribution by Scientific Domains

Polymers and Materials Science	75%

Selected Abstracts

Use of Reversal Nanoimprinting of Nanoparticles to Prepare Flexible Waveguide Sensors Exhibiting Enhanced Scattering of the Surface Plasmon Resonance

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2010
Dehui Wan
Abstract A flexible surface plasmon resonance (SPR)-based scattering waveguide sensor is prepared by directly imprinting hollow gold nanoparticles (NPs) and solid gold NPs onto flexible polycarbonate (PC) plates,without any surface modification,using a modified reversal nanoimprint lithography technology. Controlling the imprinting conditions, including temperature and pressure, allows for the fine adjustment of the depths of the embedded metal NPs and their SPR properties. This patterning approach exhibits a resolution down to the submicrometer level. A 3D finite-difference time domain simulation is used to examine the optical behavior of light propagating parallel to the air/substrate interface within the near-field regime. Consistent with the simulations, almost an order of magnitude enhancement in the scattering signal after transferring the metal NPs from the glass mold to the PC substrate is obtained experimentally. The enhanced signal is attributed to the particles' strong scattering of the guiding-mode waves (within the waveguide) and the evanescent wave (above the waveguide) simultaneously. Finally, the imprinting conditions are optimized to obtain a strongly scattering bio/chemical waveguide sensor. [source]

Investigations on the Structural Damage in Human Erythrocytes Exposed to Silver, Gold, and Platinum Nanoparticles

ADVANCED FUNCTIONAL MATERIALS, Issue 8 2010
P. V. Asharani
Abstract Human erythrocytes or red blood cells (RBCs), which constitute 99% of blood cells, perform an important function of oxygen transport and can be exposed to nanoparticles (NPs) entering into the human body during therapeutical applications involving such NPs. Hence, the haemocompatibility of the Ag, Au, and Pt NPs on human RBCs is investigated. The parameters monitored include haemolysis, haemagglutination, erythrocyte sedimentation rate, membrane topography, and lipid peroxidation. The findings suggest that platinum and gold NPs are haemocompatible compared to Ag NPs. Erythrocytes exhibit significant lysis, haemagglutination, membrane damage, detrimental morphological variation, and cytoskeletal distortions following exposure to Ag NPs at a concentration of 100,µg,mL,1. Exposure of Ag+ to RBCs shows no lysis or deterioration, implying that the observed toxicity is solely due to NPs. The haemolyzed erythrocyte fraction has the ability to induce DNA damage in nucleated cells. Additionally, multiple pits and depressions are observed on RBC membrane following exposure to Ag NPs (50,µg,mL,1 onwards). Hence, it is apparent that Ag NPs exhibit toxicity on RBCs and on other cells that are exposed to NP-mediated haemolyzed fractions. [source]

Synthesis of Au@SiO2 Core/Shell Nanoparticles and their Dispersion into an Acrylic Photocurable Formulation: Film Preparation and Characterization

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 22 2008
Marco Sangermano
Abstract Au core/silica shell (Au@SiO2) nanoparticles were synthesized by coating gold NPs with sol/gel silica in alcoholic solution. The alcoholic dispersion was added, in the range of 1,5 wt.-%, to TPGDA and photocured by means of UV light. Transparent coatings were obtained and they can find suitable applications. It was shown that the NPs can restrict the segmental motion and decrease the free volume of the polymer network, with a consequent increase in glass transition temperature. TEM analysis put in evidence that the particles are well dispersed without any macroscopic agglomeration, and many particles are present as isolated particles. [source]

Bimetallic Au,Ni Nanoparticles Embedded in SiO2 Nanospheres: Synergetic Catalysis in Hydrolytic Dehydrogenation of Ammonia Borane

CHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2010
Hai-Long Jiang Dr.
Abstract Gold,nickel nanoparticles (NPs) of 3,4,nm diameter embedded in silica nanospheres of around 15,nm have been prepared by using [Au(en)2Cl3] and [Ni(NH3)6Cl2] as precursors in a NP-5/cyclohexane reversed-micelle system, and by in situ reduction in an aqueous solution of NaBH4/NH3BH3. Compared with monometallic Au@SiO2 and Ni@SiO2, the as-synthesized Au,Ni@SiO2 catalyst shows higher catalytic activity and better durability in the hydrolysis of ammonia borane, generating a nearly stoichiometric amount of hydrogen. During the generation of H2, the synergy effect between gold and nickel is apparent: The nickel species stabilizes the gold NPs and the existence of gold helps to improve the catalytic activity and durability of the nickel NPs. [source]