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At least 109 records · Page 6Linked to original sources
PubMed1994

Gold dermatitis due to ear piercing: correlations between gold and mercury hypersensitivities.

A case of allergic contact dermatitis due to gold pierced earrings is reported. The patient developed recurring redness and swelling on her earlobes a month after the wearing of pierced-type gold earrings, which was followed by the appearance of reddish nodules around the puncture marks. Patch tests revealed positive reactions to 0.1% mercuric chloride, 1% gold sodium thiomalate and 0.2% chloroauric acid. We also demonstrated that guinea pigs contact-sensitized with a mercuric compound developed positive patch test reactions to both mercuric and gold compounds. These results suggest that there may be correlations between gold and mercury hypersensitivities.

Adult↗
PubMed2003

Aurophilicity-coordination interplay in the design of cyano-bridged nickel(II)-Gold(I) bimetallic assemblies: structural and computational studies of the gold(I)-gold(I) interactions.

Two polymorphic cyano-bridged Au(I)-Ni(II) bimetallic complexes of formulas [Ni(en)2Au(CN)2][Au(CN)2] (1) and [Ni(en)2[Au(CN)2]2] (2) have been prepared from the 1:2 reaction between [Au(CN)2]- and either [Ni(en)2Cl2]Cl or [Ni(en)3]Cl2.2H2O, respectively. The structure of 1 consists of polymeric cationic chains of alternating [Au(CN)2]- and [Ni(en)2]2+ units running along the a axis and [Au(CN)2]- anions lying between the chains. The noncoordinated dicyanoaurate anions are aligned perpendicular to the ac plane and involved in aurophilic interactions with the bridging dicyanoaurate groups, ultimately leading to a 2D bimetallic grid. The structure of 2 consists of trinuclear molecules made of two [Au(CN)2]- anions linked to [Ni(en)2]2+ unit in trans configuration. Trinuclear units are joined by aurophilic interactions to form 1D zigzag chains. The magnetic properties of these compounds are strongly dominated by the local anisotropy of the octahedral Ni(II) ions, thus indicating that the magnetic exchange interaction mediated by dicyanoaurate bridging groups, if it exists, is very weak. To get insight into the electronic properties of the inter- and intramolecular interactions of the [Au(CN)2]- building blocks, the structures of different aggregates of dicyanogold units were optimized and then analyzed by making use of atoms-in-molecules (AIM) theory. Moreover, bond indices were calculated by methods based upon nonlinear population analysis.

Journal Article↗
PubMed2006

Electrochemical formation of crooked gold nanorods and gold networked structures by the additive organic solvent.

Crooked gold nanorods (CGNRs) and gold network structures are fabricated using a simple electrochemical approach. The growth solution is prepared by surfactant solution as micelle templates with isopropanol (IPA) solvent. The shape of crooked nanorods and networks structure depend on the amount of added IPA solvent. To investigate the influence of isopropanol solvent on the CGNRs, the amount of IPA was varied in the range from 0.05 to 0.2 mL. It was found that the aspect ratios (gamma) of CGNRs were in the range from 1.06 to 1.46, and the UV-vis absorption measurement revealed a pronounced red-shift of the surface plasmon resonance (SPR) band from 532 to 560 nm. High-resolution transmission electron microscopy (HRTEM) showed that the formation of crooked nanorod structure was induced by aggregation of many small gold nuclei between the several large gold nanoparticles during growth, causing the small gold nuclei to link the gold nanoparticles. The CGNRs have a polycrystalline structure via the analysis from selected-area electron diffraction (SAED).

Journal Article↗
PubMed2005

Direct evidence of oxidized gold on supported gold catalysts.

Supported gold catalysts have drawn worldwide interest due to the novel properties and potential applications in industries. However, the origin of the catalytic activity in gold nanoparticles is still not well understood. In this study, time-of-flight secondary ion mass spectroscopy (TOF-SIMS) has been applied to investigate the nature of gold in Au (1.3 wt %)/gamma-Al2O3 and Au (2.8 wt %)/TiO2 catalysts prepared by the deposition-precipitation method. The SIMS spectrum of the supported gold catalysts presented AuO-, AuO2-, and AuOH- ion clusters. These measurements show direct evidence for oxidized gold on supported gold catalysts and may be helpful to gaining better understanding of the origin of the catalytic activity.

Letter↗
PubMed2005

Size-selective synthesis and stabilization of gold organosol in C(n)TAC: enhanced molecular fluorescence from gold-bound fluorophores.

Gold nanoparticles of variable sizes have been synthesized in toluene employing two-phase (water-toluene) extraction of AuCl4- followed by its reduction with sodium borohydride in the presence of a series of cationic surfactants of a homologous series having the general formula C(n)TAC. The solubility features of the gold particles in the organic solvent have been accounted qualitatively by calculating the van der Waals interaction potential between the particles. The effect of thermal energy and medium dielectric constant on the stability of metal particles has been studied by measuring the surface plasmon resonance. The stabilization of surfactant-mediated gold particles as hydrosol or organosol has been elucidated by considering the double-layer interaction as a function of the dielectric constant of the solvent medium. The influence of the counterion of the phase transfer reagent and stabilizing ligand on the photochemical stability of the gold colloids has been investigated. The fluorescence probe 1-methylaminopyrene (MAP) was considered for the surface functionalization of the gold particles, and it has been found that there is an enhancement of molecular fluorescence from the gold-probe assembly.

Journal Article↗
PubMed2004

Hyper-Rayleigh scattering of gold nanorods and their relationship with linear assemblies of gold nanospheres.

The surface plasmon enhanced hyper-Rayleigh scattering light collected from an aqueous solution of gold nanorods is reported. A non negligible part of the signal is attributed to a photoluminescence background attributed to the electron hole recombination following multiphoton excitation of d-valence band electrons into the sp-conduction band. This radiative relaxation process is likely favored by the presence of the organic species adsorbed at the surface of the nanorods. The absolute value for the hyperpolarisability of nanorods is also compared by the external reference method to that of para-nitroaniline and found to be rather large although an absolute value cannot be given because the exact number density of the gold nanorods is unaccessible. This value is however compared with values reported for linear assemblies of gold spherical nanoparticles and further support the simple model of gold metal ellipsoids to describe the hyper-Rayleigh light intensities. The polarisation analysis of the hyper-Rayleigh scattering light is also determined for gold nanorods and compared to the expected one for gold nanospheres. For the latter spheres, the weakness of the signal intensities precludes a definite comparison with the model. On the opposite, for the nanorods, the polarisation dependence of the hyper-Rayleigh scattered light clearly deviates from the one expected for nanospheres.

Journal Article↗
PubMed2003

Theoretical analysis of gold-deposited optical fiber sensor and characterization of the gold film.

Gold-deposited optical fiber sensors with film thicknesses from 30 to 60 nm were prepared, and the responses to a wide range of a refractivity (1.33-1.54 refractive index (RI) units) were investigated both experimentally and theoretically. The response curve of the sensor has two minima in the refractivity range from 1.33 to 1.44 and at 1.462 RI units. The former minimum is due to surface plasmon resonance (SPR) in the thin gold film, and shifts to a lower refractivity as the film becomes thicker. The response curves of the sensors with film thicknesses of 45 and 60 nm agreed well with those calculated from SPR theoretical equations. Morphology observations of the surfaces of deposited gold films on glass by atomic force microscopy (AFM) and a variation in resistance of the films with various thicknesses show the structure of the gold films. We concluded that the thin deposited gold films have many defects, and that the core of the gold-deposited optical fiber leaks light through the defects to the sample solution with the same refractivity (1.462 RI units) as that of the core.

Journal Article↗
PubMed1986

Characterization of protein-bound gold in rat urine following aurothiomalate administration and of rat and human albumin-gold-thiomalate.

The metabolites of gold in the urine of rats given the antiarthritic drug aurothiomalate were investigated by gel permeation chromatography, electrophoresis, and chemical studies. Following a single dose of aurtothiomalate, the excreted gold was protein-bound in the high-molecular-weight (greater than or equal to 150,000 dalton) and serum albumin fractions. Electrophoresis confirmed the presence of albumin, but showed that the other proteins present differ from those in normal or in vitro aurothiomalate-incubated rat sera. The pattern of the proteins establishes that the proteinuria was of the glomerular type. The alterations in the gold distribution produced by incubation of the urine with the low-molecular-weight thiol penicillamine and with exogenously added aurothiomalate indicated the existence of a labile equilibrium of gold among protein binding sites in the urine. Incubation of rat and human sera and commercially prepared serum albumins with aurothiomalate increased the electrophoretic mobility of the albumin. The significance of this change in electrophoretic mobility with respect to two models of gold binding by serum albumin is discussed.

Animals↗
PubMed1975

Accumulation of gold in various organs of mice injected with gold thioglucose.

The response of either male or female mice to the administration of gold thioglucose (GTG) was observed in food intake, in body and organ weights, and in gold accumulation in respective organs. Male mice were more sensitive to GTG toxicity than females. During 103 days after GTG administration, the adipose tissues of the females and males increased in weight 15 times and 2.5 times as high as those of control mice, respectively. The weights of heart, lung, and brain were not affected by GTG administration. In the respective organs, gold concentrations, which were determined by neutron activation analysis, were high in liver, kidney, spleen, adrenal, and adipose tissue (especially in female) within a shorter time after the GTG injection. In various organs of nonobese mice, the concentrations of GTG were significantly less than those in the typical obese mice. Even after more than 100 days after injection, gold was detected in the respective organs. In the control mice without any GTG administration, no gold could be detected.

Adipose Tissue↗
PubMed1983

Proteinuria with gold therapy: when should gold be permanently stopped?

The treatment records of patients on gold therapy have been studied with particular respect to the development of proteinuria. This was classified as mild (up to 0.3 g/l), moderate (0.4-2 g/l), or heavy (more than 2.0 g/l). Particular attention was paid to the mode of onset and prognosis of the proteinuria and to subsequent gold administration. Twenty-seven patients with moderate or heavy proteinuria were identified. Two were suffering from psoriatic arthropathy, the rest were diagnosed as having rheumatoid arthritis, although three were persistently sero-negative. There was a direct correlation between the degree of proteinuria and its duration. Heavy proteinuria persisted for at least three months, whereas moderate proteinuria cleared within this period. No patient developed permanent renal impairment. Nine of 10 patients with heavy proteinuria had preceding mild or moderate proteinuria during which period gold administration had been continued. Fourteen of 17 patients with moderate proteinuria had their gold injections continued or re-started and none of these subsequently developed heavy proteinuria. It is suggested that moderate proteinuria should lead to cessation of gold therapy until the urine is clear but that subsequently treatment may be safely re-started.

Adult↗
PubMed1989

The effect of continuing penicillamine and gold treatment on the course of penicillamine and gold nephropathy.

The effect of continuing penicillamine or gold treatment was examined in 53 patients with biopsy proven penicillamine (32) or gold (21) nephropathy. Thirty-two patients stopped penicillamine or gold treatment as soon as proteinuria was detected whilst 21 patients continued treatment for periods of 2-11 months. The 24-hour creatinine clearance and urinary protein excretion were measured serially for a median period of 6 years. No significant differences were observed in the initial or maximum proteinuria, the duration of the proteinuria or in the initial or latest creatinine clearances between the groups of patients. These results indicate that penicillamine or gold treatment may be continued for short periods under close supervision despite moderate proteinuria without causing permanent renal damage. As several alternative non-nephrotoxic agents are available for the treatment of rheumatoid arthritis, continued treatment with penicillamine or gold despite proteinuria is seldom indicated.

Aged↗
PubMed2006

Biomineralization of gold: biofilms on bacterioform gold.

Bacterial biofilms are associated with secondary gold grains from two sites in Australia. 16S ribosomal DNA clones of the genus Ralstonia that bear 99% similarity to the bacterium Ralstonia metallidurans-shown to precipitate gold from aqueous gold(III) tetrachloride-were present on all DNA-positive gold grains but were not detected in the surrounding soils. These results provide evidence for the bacterial contribution to the authigenic formation of secondary bacterioform gold grains and nuggets.

Bacteria↗
PubMed1992

[A case of gold-induced pneumonitis showing a positive reaction in the drug lymphocyte stimulation test (DLST) for gold].

A case of acute interstitial pneumonia developing during gold therapy is reported. A 67-year-old female with rheumatoid arthritis for about twenty years who received a total dose of 80 mg of gold thiomalate (Shiosol) for about two months, developed high fever and dry cough. Exertional dyspnea developed and chest roentgenogram showed diffuse small nodular and reticular shadows. RA and RAPA tests were positive. Drug lymphocyte stimulation test (DLST) for Shiosol was positive. The dyspnea resolved on administration of methylprednisolone. Chest roentgenogram and CT-scan showed improvement. A total dose of 80 mg of gold thiomalate, as administered in this case, is the minimum dose previously reported in Japan. It has been recently reported that allergic reaction is the mechanism of gold lung. In the present case, positive DLST indicated the existence of many activated lymphocytes, and was very useful in the diagnosis of gold lung.

Aged↗
PubMed1987

The mechanism of acute cytotoxicity of triethylphosphine gold(I) complexes. I. Characterization of triethylphosphine gold chloride-induced biochemical and morphological changes in isolated hepatocytes.

Triethylphosphine gold complexes are effective therapeutic agents used for the treatment of rheumatoid arthritis. Many of those molecules are also highly cytotoxic in vitro and can inhibit DNA and protein synthesis. Preliminary experiments have indicated that triethylphosphine gold chloride (TEPAu) may induce the peroxidative decomposition of cellular membrane lipids. The purpose of these investigations therefore was to evaluate the role of lipid peroxidation in the mechanism of acute cytotoxicity of a gold(I) coordination complex, TEPAu, and to examine the early morphological and biochemical changes induced by TEPAu in suspensions of freshly isolated rat hepatocytes. TEPAu caused a rapid loss of cell viability at concentrations above 25 microM which was significantly different from that of control by 60 min and complete by 180 min of incubation. TEPAu also depleted cells of reduced glutathione (GSH) and increased the formation of malondialdehyde (MDA) by 60 min. Incubation of cells with either of the antioxidants, N,N'-diphenyl-p-phenylenediamine (DPPD) or promethazine blocked the formation of MDA but did not alter the time course of cell death or GSH depletion induced by TEPAu. TEPAu also caused a decrease in cellular NADPH and NADH by 10 min. Electron microscopy of hepatocytes exposed to TEPAu revealed early (5 min) formation of flocculent electron-dense precipitates within condensed mitochondria. These changes characteristically preceded cell death. Energy-dispersive electron-probe microanalysis indicated that the electron-dense precipitates did not contain detectable amounts of gold. TEPAu also caused a concentration-dependent decrease in cellular ATP and oxygen consumption in isolated rat hepatocytes. These data suggest that lipid peroxidation, as indicated by the formation of MDA, is probably not a major mechanism by which triethylphosphine gold complexes lethally injure cells. These data, therefore, suggest that mitochondria may be target organelles in TEPAu-induced toxicity to isolated rat hepatocytes.

Animals↗
PubMed2005

Synthesis and X-ray structures of dinuclear and trinuclear gold(I) and dinuclear gold(II) amidinate complexes.

The structures of the trinuclear gold(I), [Au(3)(2,6-Me(2)-form)(2)-(THT)Cl], the dinuclear [Au(2)(2,6-Me(2)-form)(2)], and the oxidative-addition product [Au(2)(2,6-Me(2)-form)(2)Cl(2)] formamidinate complexes are reported. The trinuclear complex is stable with gold-gold distances 3.01 and 3.55 A. The gold-gold distance in the dinuclear complex decreases upon oxidative-addition with halogens from 2.7 to 2.5 A, similar to observations made with the dithiolates and ylides.

Journal Article↗
PubMed2006

Synthesis and solution- and solid-state characterization of gold(I) rings with short Au...Au interactions. Spontaneous resolution of a gold(I) complex.

We report the synthesis and solution- and solid-state characterization of gold(I) rings with short 1,9-transannular Au...Au interactions. The 9- and 16-membered gold(I) rings were prepared by reacting 9,9-dimethyl-4,5-bis(diphenylphosphino)-xanthene and (Me2S)AuCl in the presence of AgNO3 in the molar ratio of 1:0.5:1 and 1:1:1, respectively. X-ray crystallographic measurements in conjunction with solution X-ray diffraction and NMR methods have been used to determine the structure of gold(I) rings, and we also gained insight into the dynamics. The nine-membered gold(I) ring is chiral, and the crystal contains only one of the two enantiomers, either right- or left-handed. To the best of our knowledge this represents the first example of crystallization-induced spontaneous resolution of a binuclear gold(I) cycle. The 16-membered ring with 1,9-transannular Au...Au interaction is in a figure-eight conformation.

Journal Article↗