Colloidal Gold Nanoparticles (colloidal + gold_nanoparticle)

Distribution by Scientific Domains


Selected Abstracts


Multilayer Assembly of Hemoglobin and Colloidal Gold Nanoparticles on Multiwall Carbon Nanotubes/Chitosan Composite for Detecting Hydrogen Peroxide

ELECTROANALYSIS, Issue 19 2008
Shihong Chen
Abstract Chitosan (CS) was chosen for dispersing multi-wall carbon nanotubes (MWNTs) to form a stable CS-MWNTs composite, which was first coated on the surface of a glassy carbon electrode to provide a containing amino groups interface for assembling colloidal gold nanoparticles (GNPs), followed by the adsorption of hemoglobin (Hb). Repeating the assembly step of GNPs and Hb resulted in {Hb/GNPs}n multilayers. The assembly of GNPs onto CS-MWNTs composites was confirmed by transmission electron microscopy. The consecutive growth of {Hb/GNPs}n multilayers was confirmed by cyclic voltammetry and UV-vis absorption spectroscopy. The resulting system brings a new platform for electrochemical devices by using the synergistic action of the electrocatalytic activity of GNPs and MWNTs. The resulting biosensor displays an excellent electrocatalytic activity and rapid response for hydrogen peroxide. The linear range for the determination of H2O2 was from 5.0×10,7 to 2.0×10,3 M with a detection limit of 2.1×10,7 M at 3, and a Michaelis,Menten constant KMapp value of 0.19,mM. [source]


Nanoarrays: Cooperative Near-Field Surface Plasmon Enhanced Quantum Dot Nanoarrays (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 16 2010
Mater.
Abstract Fluorescence from quantum dots (QDs) sandwiched between colloidal gold nanoparticles and lithographically created metal nanoarrays is studied using engineered peptides as binding agents. For optimized structures, a 15-fold increase is observed in the brightness of the QDs due to plasmon-enhanced fluorescence. This enhanced brightness is achieved by systematically tuning the vertical distance of the QD from the gold nanoparticles using solid-specific peptide linkers and by optimizing the localized surface plasmon resonance by varying the geometric arrangement of the patterned gold nanoarray. The size and pitch of the patterned array affect the observed enhancement, and sandwiching the QDs between the patterned features and colloidal gold nanoparticles yields even larger enhancements due to the increase in local electromagnetic hot spots induced by the increased surface roughness. The use of bifunctional biomolecular linkers to control the formation of hot spots in sandwich structures provides new ways to fabricate hybrid nanomaterials of architecturally induced functionality for biotechnology and photonics. [source]


Cooperative Near-Field Surface Plasmon Enhanced Quantum Dot Nanoarrays

ADVANCED FUNCTIONAL MATERIALS, Issue 16 2010
Kirsty Leong
Abstract Fluorescence from quantum dots (QDs) sandwiched between colloidal gold nanoparticles and lithographically created metal nanoarrays is studied using engineered peptides as binding agents. For optimized structures, a 15-fold increase is observed in the brightness of the QDs due to plasmon-enhanced fluorescence. This enhanced brightness is achieved by systematically tuning the vertical distance of the QD from the gold nanoparticles using solid-specific peptide linkers and by optimizing the localized surface plasmon resonance by varying the geometric arrangement of the patterned gold nanoarray. The size and pitch of the patterned array affect the observed enhancement, and sandwiching the QDs between the patterned features and colloidal gold nanoparticles yields even larger enhancements due to the increase in local electromagnetic hot spots induced by the increased surface roughness. The use of bifunctional biomolecular linkers to control the formation of hot spots in sandwich structures provides new ways to fabricate hybrid nanomaterials of architecturally induced functionality for biotechnology and photonics. [source]


Gastrointestinal persorption and tissue distribution of differently sized colloidal gold nanoparticles

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2001
Julián F. Hillyer
Abstract The gastrointestinal uptake of micro- and nanoparticles has been the subject of recent efforts to develop effective carriers that enhance the oral uptake of drugs and vaccines. Here, we used correlative instrumental neutron activation analysis and electron microscopy to quantitatively and qualitatively study the gastrointestinal uptake and subsequent tissue/organ distribution of 4, 10, 28, and 58 nm diameter metallic colloidal gold particles following oral administration to mice. In our quantitative studies we found that colloidal gold uptake is dependent on particle size: smaller particles cross the gastrointestinal tract more readily. Electron microscopic studies showed that particle uptake occurred in the small intestine by persorption through single, degrading enterocytes in the process of being extruded from a villus. To our knowledge this is the first report, at the ultrastructural level, of gastrointestinal uptake of particulates by persorption through holes created by extruding enterocytes. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1927,1936, 2001 [source]


Positron Annihilation Lifetimes in Cucurbiturils: Evidence of Internal Inclusion of Gold in CB[7]

CHEMPHYSCHEM, Issue 5 2009
Pedro Montes-Navajas
Abstract Positron lifetime spectroscopy serves to determine the void volumes of cucurbituril (CB) capsules, which are not amenable to standard gas adsorption methods. In the case of the host,guest complex Au§CB[7], it also provides evidence of the inclusion of gold nanoparticles in the CB cavity (see space-filling model; Au golden, C gray, H cyan, N blue, O red). Positron annihilation lifetime (PAL) measurements are carried out to determine the cavity dimensions of hydrated and dehydrated cucurbiturils (CB[n]; n=5,6,7,8). In the case of hydrated samples, the dimensions of the cavity are unrelated to the number of glycoluril units of the CB, whereas for dehydrated samples the cavity dimensions measured by PAL follow the expected order, although the experimental values obtained by PAL are significantly smaller than the dimensions of each CB determined by crystallography. For a host,guest complex in which colloidal gold nanoparticles are assumed to be included inside CB[7], a significant reduction of the cavity size is measured. This represents an experimental evidence of the inclusion of gold inside CB[7], which complements previous high-resolution transmission electron microscopy (TEM) images. [source]