A new procedure for the preparation of biocompatible gold nanoparticles using bioflavonoids: rutin, quercetin, and luteolin
as reducing agents and stabilizers was proposed. On varying the bioflavonoid concentration, nanoparticles of different size
are formed. By the combined use of spectroscopy and atomic force microscopy, the nanoparticle size was estimated (40–50 nm).
Uniform and highly dispersed gold nanoparticles were obtained at Au: rutin ratios of 1: 1, 2: 1, and 4: 1 and Au: quercetin
ratios of 2: 1 and 4: 1. The nanoparticle yield remains almost constant as the Au: rutin ratio varies over a broad range from
1: 1 to 12: 1. It was suggested that complete reduction of AuIII to Au0 with a large excess of Au is accompanied by extensive oxidation of bioflavonoid involving an intermediate oxidant formed
in the system due to the high oxidative capacity of AuIII. For elucidating the catalytic role of bioflavonoids in the formation of gold nanoparticles, quantum chemical modeling of
the process was performed. 相似文献
We use colloidal Au to enhance the DNA immobilization amount on a gold electrode and ultimately lower the detection limit of our electrochemical DNA biosensor. Self-assembly of approximately 16-nm diameter colloidal Au onto a cysteamine modified gold electrode resulted in an easier attachment of an oligonucleotide with a mercaptohexyl group at the 5′-phosphate end, and therefore an increased capacity for nucleic acid detection. Quantitative results showed that the surface densities of oligonucleotides on the Au colloid modified gold electrode were approximately (1–4)×1014 molecules cm−2. Hybridization was induced by exposure of the ssDNA-containing gold electrode to ferrocenecarboxaldehyde labeled complementary ssDNA in solution. The detection limit is 5×10−10 mol l−1 of complementary ssDNA, which is much lower than our previous electrochemical DNA biosensors. The Au nanoparticle films on the Au electrode provide a novel means for ssDNA immobilization and sequence-specific DNA detection. 相似文献
A sensitive competitive flow injection chemiluminescence (CL-FIA) immunoassay for immunoglobulin G (IgG) was developed using gold nanoparticle as CL label. In the configuration, anti-IgG antibody was immobilized on a glass capillary column surface by 3-(aminopropyl)-triethoxysilane and glutaraldehyde to form immunoaffinity column. Analyte IgG and gold nanoparticle labeled IgG were passed through the immunoaffinity column mounted in a flow system and competed for the surface-confined anti-IgG antibody. CL emission was generated from the reaction between luminol and hydrogen peroxide in the presence of Au (III), generated from chemically oxidative dissolution of gold nanoparticle by an injection of 0.10 mol L−1 HCl–0.10 mol L−1 NaCl solution containing 0.10 mmol L−1 Br2. The concentration of analyte IgG was inversely related to the amount of bound gold nanoparticle labeled IgG and the CL intensity was linear with the concentration of analyte IgG from 1.0 ng mL−1 to 40 ng mL−1 with a detection limit of 5.2 × 10−10 g mL−1. The whole assay time including the injections and washing steps was only 30 min for one sample, which was competitive with CL immunoassays based on a gold nanoparticle label and magnetic separation. This work demonstrates that the CL immunoassay incorporation of nanoparticle label and flow injection is promising for clinical assay with sensitivity and high-speed. 相似文献
Patterned arrays of gold nanoparticles were fabricated using a simple dipping method that makes use of their specific interactions with nano-domains of carboxylic acid on a block copolymer template. Polystyrene-block-poly(tert-butyl acrylate) on the SU-8 photoresist pattern was selectively transformed to polystyrene-block-poly(acrylic acid). Au nanoparticles are selectively immobilized on the resulting carboxylic acid patterns to produce well-defined patterned Au nanoparticle arrays. This stable and robust template can be used to obtain any patterned nonaggregated metal or inorganic nanoparticle arrays. 相似文献
In our work, the photonuclear production of 198,199Au isotopes for nuclear medicine purposes was studied, and a method for their recovery from irradiated mercury was developed. The yields of the corresponding nuclear reactions were determined, and a comparison of various methods of obtaining gold radioisotopes was provided. New sorbents based on benzo-15-crown-5, which selectively binds gold, were studied, and the optimal conditions for Au recovery with a high degree of purification from mercury were found. It was established that, for the fast and quantitative recovery of Au isotopes, it was necessary to add at least 0.1 mg of the carrier. As a result, the developed method can be regularly used to obtain 198,199Au for the research of radiopharmaceuticals based on them. 相似文献
Gold nanoparticles were fabricated by reduction of highly concentrated Au(III) ions (200 mM) with casein proteins from milk. The gold nanoparticles were converted to nanoparticle-powders after washing and subsequent vacuum drying without aggregation. The nanoparticle-powders completely re-dispersed in aqueous solution, and stable colloidal gold nanoparticles were obtained. UV-vis extinction spectra and dynamic light scattering (DLS) measurements revealed that large assemblies (size, ca. 3 μm) and subaggregates (size, <0.5 μm) composed of gold nanoparticle-casein protein chain-Au(III) ion were dynamically formed and disintegrated over the course of the growth of the gold nanoparticles. Fourier transform infrared (FT-IR) spectra indicated conformational changes of casein proteins induced by the interaction of casein protein-Au(III) ion and -gold nanoparticle. Finally, rapid, one-pot, and highly concentrated synthetic procedures of gold and silver nanoparticle powders protected by casein (mean diameters below 10 nm) were successfully developed using 3-amino-1-propanol aqueous solutions as reaction media. Dense colloidal gold (40 g L(-1)) and silver (22 g L(-1)) nanoparticle aqueous solutions were obtained by re-dispersing the metal nanoparticle powders. 相似文献
The determination of Ir and Pt in rhodium neutron monitors was investigated via192Ir and199Au after neutron activation, via191Pt and194Au–196Au after proton activation. Ir was determined by instrumental NAA. A chemical separation of gold, with a yield measurement method by a radioactive tracer, was developed for platinum determination after neutron or proton irradiation. 相似文献
A single nanoparticle (NP) attached to a nanoelectrode is a very useful system in understanding the relationship between the size of nanoparticles and their electrochemical properties. In this study, a single Au NP was spontaneously formed on a Pt nanoelectrode. The potential measured on such a system can be employed to study the effect of size of an Au nanoparticle on the Nernst potential of the reaction, AuCl4− +3e → Au(s) +4Cl−. Moreover, the nucleation period and the growth period can be distinguished from the potential graph, and the nucleation rate of the spontaneously formed Au NP can be evaluated. 相似文献
The adsorption structure and mechanism of 4,4′-bipyridine (BiPy) on gold nanoparticle surfaces has been investigated by means of surface-enhanced Raman scattering (SERS). The aromatic ring of BiPy appeared to assume a perpendicular orientation with respect to the gold surface from the presence of the ν(CH) band at ∼3060 cm−1. The SERS intensities of several vibrational modes of BiPy on Au were found to vary as the bulk concentration. The SERS intensities for BiPy on Au could be ascribed to both the electromagnetic (EM) and charge transfer (CT) enhancement mechanism. 相似文献
An easy method of preparation of polymer/metal–nanoparticle composites is reported. KAu(CN)2 and pyrrole do not react (redox reaction) in solutions of moderate pH. The gold complex, due to its inertness, is stable in the presence of 10 μM CN? for weeks. Therefore the electrodeposition of controlled amounts of polypyrrole and Au nanoparticles on the graphite surface can be done in one solution by applying a sequence of 0.75 and ? 1.6 V potentials. Pulse deposition of both components leads to substantial improvement of the layer smoothness and homogenous distribution of Au nanocrystallites. 相似文献
A method is described for the determination of traces of gold in copper and cadmium by neutron activation analysis, using
anion exchange resin as a preconcentration agent: gold was separated from large amount of copper or cadmium with Cl-form Dowex
1X8 AG, 100–200 mesh, resin. To reduce the interfering activities, the resin was irradiated in NO
3−
-form and washed with dilute hydrochloric acid after irradiation.198Au in the resin was then counted with a Ge(Li) or NaI(Tl) detector. The chemical yields were more than 99%. The concentration
factors of gold for copper and cadmium samples were 1.1×108 and 2.7×106, respectively. The analytical results of gold in 99.99% copper and 99.999% cadmium were 65 and 0.15 ppb, respectively. The
blank was 0.05 ng Au per 200 mg of wet resin. 相似文献
Gold nanoparticle is an important nanomaterial and has been investigated widely owing to its special physical and chemical property[1―5]. In recent years it has been found that the multiple-component nano- structure assembly containing metal, semiconduct… 相似文献
We performed computational and experimental studies of the feasibility of the gold bearing ore assay utilizing the 197Au(γ,n)196Au photonuclear reaction. Gold bearing silicate samples were irradiated using bremsstrahlung produced by an electron accelerator with endpoint energies ranging from 25 to 40 MeV. 196Au yield simulations were benchmarked and experimental results were in good agreement with the predictions. Optimum electron beam energy for photon activation analysis was found to be around 32 MeV which corresponded to a detection limit of 80 ppb. Two-hour gamma-spectroscopy measurements were repeated every 24 h and the optimum sample cooling time was found to be about 100–160 h. 相似文献
The geometrical structure of the Au‐Fe2O3 interfacial perimeter, which is generally considered as the active sites for low‐temperature oxidation of CO, was examined. It was found that the activity of the Au/Fe2O3 catalysts not only depends on the number of the gold atoms at the interfacial perimeter but also strongly depends on the geometrical structure of these gold atoms, which is determined by the size of the gold particle. Aberration‐corrected scanning transmission electron microscopy images unambiguously suggested that the gold particles, transformed from a two‐dimensional flat shape to a well‐faceted truncated octahedron when the size slightly enlarged from 2.2 to 3.5 nm. Such a size‐induced shape evolution altered the chemical bonding environments of the gold atoms at the interfacial perimeters and consequently their catalytic activity. For Au particles with a mean size of 2.2 nm, the interfacial perimeter gold atoms possessed a higher degree of unsaturated coordination environment while for Au particles with a mean size of 3.5 nm the perimeter gold atoms mainly followed the atomic arrangements of Au {111} and {100} facets. Kinetic study, with respect to the reaction rate and the turnover frequency on the interfacial perimeter gold atom, found that the low‐coordinated perimeter gold atoms were intrinsically more active for CO oxidation. 18O isotopic titration and Infrared spectroscopy experiments verified that CO oxidation at room temperature occurred at the Au‐Fe2O3 interfacial perimeter, involving the participation of the lattice oxygen of Fe2O3 for activating O2 and the gold atoms for CO adsorption and activation. 相似文献
Molecular dynamics simulations were carried out to investigate the structure of a gold‐nanoparticle including 169 Au atoms coated by 42 thiol terminated hydroquinonyl oligoether chains. Three nanoparticle systems were constructed and investigated for structural comparison. The simulation showed that in all three nanosystems thiol‐chains self‐assembled on the surface of the gold cluster to form a stable gold nanoparticle. The configurations of the thiol chains and stacking of the phenylene rings were analyzed. The thiol‐chains are bundled into groups. Each group contains no more than four chains, in which phenylene rings in the thiol‐chains are correlated in parallel and perpendicular forms. Simple quantum mechanical calculations are carried out to elucidate the correlation of the phenylene rings.
Stable colloidal solutions of gold nanoparticles surface-derivatized with a thiol monolayer have been prepared using two-phase (water–nitrobenzene) reduction of AuCl4− by sodium borohydride in the presence of 2-mercapto-3-n-octylthiophene (MOT). This kind of surface-functionalized gold nanoparticles can be easily incorporated into the poly(3-octylthiophene) (POT) films on electrode in the process of electrochemical polymerization leading to POT–gold nanoparticle (POT–Au) composite films. Scanning probe microscopy (SPM) and X-ray photoelectric spectroscopy (XPS) have been employed to characterize the surface-derivatized particles and the resulting films. The method of incorporation of nanoparticles into polymer by surface-derivatization and in situ polymerization can also be employed to prepare many other polymer–nanoparticle compostie materials. 相似文献
Sulfonated graphene nanosheet/gold nanoparticle (SGN/Au) hybrid was synthesized by electrostatic self-assembly of anionic SGN and positively charged gold nanoparticles. Due to the well-dispersivity of SGN in aqueous solution and its adequate negative charge, Au nanoparticles were assembled uniformly on graphene surface with high distribution. With the advantages of both graphene and Au nanoparticles, SGN/Au hybrid showed enhanced electrocatalytic activity towards O2 reduction. Furthermore, it provided a conductive and favorable microenvironment for the glucose oxidase (GOD) immobilization and thus promoted its direct electron transfer at the glassy carbon electrode. Based on the consumption of O2 caused by glucose at the interface of GOD electrode modified with SGN/Au hybrid, the modified electrode displayed satisfactory analytical performance, including high sensitivity (14.55 μA mM?1 cm?2), low detection limit (0.2 mM), an acceptable linear range from 2 to 16 mM, and also the prevention from the interference of some species. These results indicated that the prepared SGN/Au hybrid is a promising candidate material for high-performance glucose biosensor. 相似文献