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PubMedDate not supplied

Lack of effect of gold salts on acetylcholine or histamine contraction of canine tracheal and bronchial smooth muscle.

In vitro gold salt incubation with proximal and distal canine airway smooth muscle was compared to untreated canine airway muscle with respect to histamine and acetylcholine-induced contraction. Gold chloride and gold sodium thiomalate had no effect on either proximal or distal canine airway smooth muscle agonist-induced contraction. Gold chloride in concentrations greater than 10(-5) M had a direct contractile effect. These results differ from previous studies which showed an inhibition of the histamine response of guinea-pig tracheal smooth muscle following in vitro preincubation with gold salts. This difference suggests that the mechanism(s) of the beneficial effects of long-term gold salt therapy on human asthma cannot be reliably studied with short-term in vitro animal preparations without first assessing species differences with respect to the effects of therapeutic agents. Human airway smooth muscle preparations would be the best means of addressing this question.

Acetylcholine↗
PubMed1985

In vitro inhibition of myelopoiesis by gold salts and D-penicillamine.

Leukopenia is one of the more serious side effects of gold and D-penicillamine therapy. We report that gold salts (gold thiomalate, gold chloride and gold thioglucose) and D-penicillamine suppressed the in vitro development of colonies of myeloid cells (macrophage, granulocyte and megakaryocyte) from progenitor cells in murine bone marrow; these drugs were also effective in inhibiting the development of macrophage and granulocytic colonies in human bone marrow. The drugs generally required concentrations of 10(-5) M in the murine system, whereas they were active at 10(-7)-10(-8) for the human progenitor cells. The disease suppressive activity of gold salts and D-penicillamine could result in part from the reduction of cell numbers in arthritic lesions; our findings would provide a mechanism for this possibility.

Animals↗
PubMed1998

Preparation, use, and enlargement of ultrasmall gold particles in immunoelectron microscopy.

The introduction of ultrasmall (approximately 1-3 nm) colloidal gold markers in immunoelectron microscopy (IEM) in 1989 has considerably improved the sensitivity of this marker system. Ultrasmall gold markers have opened the field of pre-embedding labeling studies to gold markers without the need of harsh permeabilizing steps. They are recommended for the detection of scarce antigens in ultrathin cryosections which may otherwise escape immunodetection. However, reports concerning the preparation of ultrasmall gold colloids, their conjugation to proteins, and their use in high-resolution studies (without an additional enlargement step) are very limited. Also, the available enlargement techniques necessary for the use of this marker in conventional electron microscopy require detailed discussion to clarify the large number of contradictory observations. The present review summarizes and discusses the findings accumulated within the last 10 years on the application of ultrasmall gold markers in IEM with regard to their merits, limitations, detection sensitivity, and suitability for different labeling techniques. It should provide practical hints for the use of ultrasmall gold colloids and discusses problems arising with enlargement techniques such as silver enhancement and gold toning procedures.

Image Enhancement↗
PubMed2001

Adsorption of 1,4-Benzenedithiol on Gold and Silver Surfaces: Surface-Enhanced Raman Scattering Study.

The adsorption behavior of 1,4-benzenedithiol (1,4-BDT) on colloidal gold and silver surfaces has been investigated by means of surface-enhanced Raman scattering (SERS). 1,4-BDT chemisorbed dissociatively on both gold and silver surfaces but as mono- and dithiolate, respectively. Regardless of the bulk concentration of 1,4-BDT, only a monolayer was assembled on the silver surface with a flat orientation by forming two Ag-S bonds. On the gold surface, the monothiolate species,1,4-BDT(-1), appeared to assume a rather flat orientation at a very low surface coverage, but as the surface coverage was increased, the adsorbate took a perpendicular orientation. Furthermore, when the bulk concentration of 1,4-BDT was close to that required for a full-monolayer coverage limit, a band assignable to the S-S stretching vibration appeared at approximately 536 cm(-1) in the gold sol SERS spectra. A separate ellipsometry measurement performed with vacuum-evaporated gold substrates revealed that up to tetralayers could be assembled on gold in 1 mM n-hexane solution of 1,4-BDT while at best a bilayer formed in either methanol or ethanol solution. The different adsorbate structure of 1,4-BDT on gold and silver was overall quite comparable to that of p-xylene-alpha,alpha'-dithiol. Copyright 2001 Academic Press.

Journal Article↗
PubMed2002

Nanostructured gold hollow microspheres prepared on dissolvable ceramic hollow sphere templates.

Fifty and one-hundred micrometer diameter nanostructured gold hollow microspheres (GHSs), in >98% purity, have been prepared by using ceramic hollow spheres, CHSs, as templates. Tennanometer diameter gold nanoparticles were covalently linked to the thiol moiety of (3-mercaptopropyl)trimethoxysilane, which had been self-assembled onto the CHSs. Greater structural strength was obtained by the generation of additional gold nanoparticles, in situ on the gold nanoparticle coated CHSs (by immersing the gold nanoparticle coated CHSs into an aqueous mixture of hydroxylamine and gold chloride). GHSs were obtained by dissolving the CHSs templates. The sizes, shapes, surface areas (185.3 m2/g for CHSs and 182.9 m2/g for GHSs), pore diameters (7.7 nm for CHSs and 7.8 nm for GHSs), and pore volumes (0.41 cm3/g for CHSs and 0.36 cm3/g for GHSs) of GHSs were quite similar to their CHSs counterparts. Significantly, GHSs showed surface plasmon bands whose maximum (644 nm) shifted from that observed for the parent 10-nm gold nanoparticles (522 nm).

Journal Article↗
PubMed1992

Versatility of anti-horseradish peroxidase antibody-gold complexes for cytochemistry and in situ hybridization: preparation and application of soluble complexes with streptavidin-peroxidase conjugates and biotinylated antibodies.

In previous studies we have employed a gold-labelled, affinity-purified polyclonal antibody against horseradish peroxidase (anti-HRP--gold) in the avidin-biotin peroxidase complex (ABC) technique and indirect labelled avidin-biotin methods. The gold-labelled antibody was used as final revealing reagent to replace the 3,3'-diaminobenzidine (DAB) reaction by immunogold silver staining. The anti-HRP--gold reagent proved to be advantageous since blocking of endogenous peroxidase activity in the tissue sections was not further required and staining of superior contrast and resolution could be achieved in paraffin sections. In the present study we have optimized this technique by combining the last two incubation steps, i.e. HRP-conjugated streptavidin and anti-HRP--gold. Different ratios of the two reagents were tested empirically to establish the conditions for the formation of a soluble complex with optimal staining properties. Quantitative evaluation by densitometry of the staining intensity showed that the soluble streptavidin-HRP/anti-HRP--gold complex and the indirect labelled avidin-biotin method employing the gold-labelled anti-HRP antibody performed equally well. Thus, the availability of this complex simplifies the streptavidin-biotin immunogold technique for immunohistochemistry, lectin histochemistry and in situ hybridization and further demonstrates the versatility of anti-HRP--gold complexes.

Antibodies↗
PubMed2005

Column preconcentration of gold by adsorbing AuCl4- onto methyltrioctyl ammonium chloride-naphthalene and subsequent atomic absorption spectrometric determination.

A sensitive, selective and simple preconcentration method for ultra-trace gold determination has been developed that uses naphthalene-methyltrioctyl ammonium chloride (Aliquat 336s) as an adsorbent. Gold, in the form of AuCl4-, was retained by the adsorbent in the column at a flow rate of 1 ml min(-1). After filtration, the solid mass consisting of the gold complex and naphthalene was dissolved out of the column with 5 ml of N,N-dimethylformamide (DMF), and the metal was then determined by atomic absorption spectrometry. In the initial solution, the calibration graph of absorbance versus gold concentration was found to be linear in the range 0.5-150 ng ml(-1) Au(III) with r=0.997 (n=9), and the 3 s detection limit was 0.428 ng ml(-1). The relative standard deviation for eight replicate measurements of 20 microg of gold was 2.14%. Preconcentration factors of 390 and 650 were achieved using 5 ml and 3 ml of DMF, respectively. The proposed method was successfully applied to the determination of gold in wastewater, processed pool water, slurry pool water, and raw well-water from the Moteh gold mine, and synthetic samples.

Journal Article↗
PubMed1991

Neurons with access to the general circulation in the central nervous system of the rat: a retrograde tracing study with fluoro-gold.

Central nervous system neurons which have access to the general circulation were identified by injecting the retrograde tracer Fluoro-Gold peripherally. Fluoro-Gold does not penetrate the blood-brain barrier but is taken up by nerve terminals which project to areas supplied by fenestrated capillaries or to the periphery. Fluoro-Gold-accumulating neurons were present in the following regions or cell groups of the central nervous system: diagonal band of Broca; medial preoptic area; organum vasculosum of the lamina terminalis; subfornical organ; anterior periventricular area; paraventricular nucleus; arcuate nucleus; accessory magnocellular nuclei of the hypothalamus; motor neurons of cranial nerves III-VII, and IX-XII in the brainstem and spinal cord; autonomic ganglionic cells of cranial nerve III (Westphal-Edinger nucleus) in the mesencephalon and the intermediolateral column of the spinal cord; sensory ganglia of the cranial nerve V (mesencephalic trigeminal nucleus); and the C1-C2 and A2 adrenergic cell groups in the medulla. In addition, Fluoro-Gold-accumulating neurons were seen in the sensory ganglia of cranial and spinal nerves. Retrograde labeling with Fluoro-Gold can be combined with immunocytochemistry to identify the chemical messengers within Fluoro-Gold-labeled perikarya. Although a large number of neurons are labeled in the central nervous system with Fluoro-Gold when it is administered peripherally, this technique in combination with immunocytochemistry can be a powerful tool to identify selected neuronal systems in the central nervous system.

Animals↗
PubMed1991

Persistence of fluoro-gold following degeneration of labeled motoneurons is due to phagocytosis by microglia and macrophages.

When the neural tracer Fluoro-Gold is used to retrogradely label a population of axotomized neurons, cellular labeling can persist in the axotomized nucleus even when Nissl staining indicates that the injured neurons have degenerated. In order to determine the identity of the labeled cells that remain, this study combines retrograde transport of Fluoro-Gold with immunocytochemical methods for identification of specific non-neuronal cell types following peripheral axotomy and Fluoro-Gold labeling of motoneurons in the dorsal motor nucleus of the vagus in neonatal and adult rats. Fourteen days following cervical vagotomy in neonatal rats, Nissl staining revealed a virtually complete loss of vagal motoneurons. Fourteen days after cervical vagotomy in adult rats, vagal motoneuronal loss was not yet extensive but chromatolysis had clearly begun. Injection of Fluoro-Gold into the vagus nerve just prior to the vagotomy led to Fluoro-Gold labeling of remaining vagal motoneurons. In addition, many other small, brightly labeled cells were present in the lesioned vagal nuclei of all rats. Immunofluorescent identification of astrocytes with anti-glial fibrillary acidic protein and microglia and macrophages with OX42 (anti-C3bi complement receptor) and ED1 (anti-monocyte/macrophage cytoplasmic antigen) demonstrated that the small, bright Fluoro-Gold-labeled cells were non-neuronal, non-astrocytic phagocytes, including microglia. These results indicate that phagocytic microglia and other macrophages sequester Fluoro-Gold in the axotomized dorsal motor nucleus of the vagus of neonatal and adult rats, leading to persistence of fluorescent cellular labeling following the loss of retrogradely labeled axotomized neurons.

Age Factors↗
PubMed1996

Combined use of malachite green fixation and PLA2-gold complex technique to localize phospholipids in areas of early calcification of rat epiphyseal cartilage and bone.

Two cytochemical methods (malachite green fixation and PLA2-gold complex technique) were combined in order to detect the presence and ultrastructural distribution of phospholipids in epiphyseal cartilage and metaphyseal bone of 25-day-old rats. Chondrocytes and osteoblasts showed a more intense PLA2-gold complex labeling of rough endoplasmic reticulum than mitochondria and plasma membranes. Roundish osmiophilic, electron-dense, lightly labeled structures were visible at the periphery of the cells. In areas of early mineralization of cartilage, not all the matrix vesicles were labeled by PLA2-gold complex. Calcification nodules showed intense labeling in comparison with the surrounding, lightly labeled uncalcified matrix; gold particles were chiefly found at their periphery. Calcification nodules of metaphyseal bone were deeply electron-dense after glutaraldehyde-malachite green fixation; PLA2-gold labeling was mainly found in connection with crystals, whereas the uncalcified matrix was weakly labeled. Calcified bone matrix showed a heavy labeling with randomly scattered gold particles. When pre-embedding decalcification was carried out in the presence of malachite green, a good preservation of organic component was obtained. The PLA2-gold positivity of decalcified areas of cartilage and bone confirmed the presence of phospholipids in mineralized matrix.

Animals↗
PubMed2004

IgE sensitization profiles toward green and gold kiwifruits differ among patients allergic to kiwifruit from 3 European countries.

BACKGROUND: Kiwifruits have become a major elicitor of plant food allergy. Until recently, the only species of kiwifruit grown commercially was the common green-fleshed Actinidia deliciosa cv Hayward. In 1999, the yellow-fleshed cultivar Actinidia chinensis cv Hort16A was introduced into the international market. OBJECTIVE: We compared the allergen compositions of green and gold kiwifruits and assessed the sensitization patterns of patients with kiwifruit allergy toward both varieties. METHODS: Sera from 90 patients with kiwifruit allergy from Austria, central Italy, and the Netherlands were tested for IgE binding to green and gold kiwifruit protein extracts and to purified actinidin, the major kiwifruit allergen, by ELISA. In addition, ELISA inhibitions and immunoblots were performed with selected sera. Relevant allergens were identified by N-terminal sequencing and immunoblotting with allergen-specific antibodies. RESULTS: IgE immunoblotting showed marked differences in the allergen compositions of green and gold kiwifruit extracts. Phytocystatin, a novel plant food allergen, and a thaumatin-like protein were identified as allergens common for both cultivars. Two allergens with homologies to chitinases were found in gold kiwifruits, whereas actinidin was detected exclusively in green kiwifruits. Patients from Central Europe and central Italy showed distinct sensitization profiles toward green and gold kiwifruit extracts as well as actinidin. Whereas sera from Austrian and Dutch patients mainly recognized green kiwifruit extract and actinidin, almost all Italian sera showed IgE binding to both kiwifruit species, but only half of them contained actinidin-specific IgE. Green and gold kiwifruit extracts were shown to be highly cross-reactive as determined by IgE ELISA inhibition. CONCLUSION: The presence of common allergens and the IgE cross-reactivity to green kiwifruit qualifies gold kiwifruit as a potential new allergen source for patients allergic to green kiwifruits.

Actinidia↗
PubMed2006

Experimental (SERS) and theoretical (DFT) studies on the adsorption of p-, m-, and o-nitroaniline on gold nanoparticles.

Surface-enhanced Raman scattering (SERS) spectra of p-, m-, and o-nitroaniline (PNA, MNA, and ONA) adsorbed on gold nanoparticles were studied, respectively, in a gold colloidal solution and on dried gold-coated filter paper. Significant changes were found in the SERS spectra of p-, m-, and o-nitroaniline molecules adsorbed on the two substrates, indicating that the behavior of p-, m-, and o-nitroaniline adsorbed on gold nanoparticles coated on filter paper was different from that in gold aqueous colloids. Moreover, on the filter paper it was found that the SERS spectra of the PNA molecules changed with the coverage density of the gold nanoparticles, while the MNA and ONA did not evidently change. The analyses showed that the origins of these changes were the different adsorption behavior of molecules adsorbed on the gold nanoparticles and that the adsorption behavior of molecules was greatly affected by the surface characteristic of the substrate and the surface configuration of the adsorbate. In addition, the vibrational frequencies and Raman scattering intensities of the three nitroanilines were calculated by use of the density functional theory (DFT-B3LYP/6-31G(d)) method. The combination of SERS spectroscopy and DFT calculation is quite useful for studies of adsorption orientation of a molecule on a metal nanoparticle.

Journal Article↗
PubMed1998

Correlative Instrumental Neutron Activation Analysis, Light Microscopy, Transmission Electron Microscopy, and X-ray Microanalysis for Qualitative and Quantitative Detection of Colloidal Gold Spheres in Biological Specimens.

: Colloidal gold, conjugated to ligands or antibodies, is routinely used as a label for the detection of cell structures by light (LM) and electron microscopy (EM). To date, several methods to count the number of colloidal gold labels have been employed with limited success. Instrumental neutron activation analysis (INAA), a physical method for the analysis of the elemental composition of materials, can be used to provide a quantitative index of gold accumulation in bulk specimens. Given that gold is not naturally found in biological specimens in any substantial amount and that colloidal gold and ligand conjugates can be prepared to yield uniform bead sizes, the amount of label can be calculated in bulk biological samples by INAA. Here we describe the use of INAA, LM, transmission EM, and X-ray microanalysis (EDX) in a model to determine both distribution (localization) and amount of colloidal gold at the organ, tissue, cellular, and ultrastructural levels in whole animal systems following administration. In addition, the sensitivity for gold in biological specimens by INAA is compared with that of inductively coupled plasma-mass spectrometry (ICP-MS). The correlative use of INAA, LM, TEM, and EDX can be useful, for example, in the quantitative and qualitative tracking of various labeled molecular species following administration in vivo.

Journal Article↗
PubMed2000

An electrochemical metalloimmunoassay based on a colloidal gold label.

A novel, sensitive electrochemical immunoassay has been developed using a colloidal gold label that, after oxidative gold metal dissolution in an acidic solution, was indirectly determined by anodic stripping voltammetry (ASV) at a single-use carbon-based screen-printed electrode (SPE). The use of disposable electrodes allows for simplified measurement in 35 microL of solution. The method was evaluated for a noncompetitive heterogeneous immunoassay of an immunoglobulin G (IgG) and a concentration as low as 3 x 10(-12) M was determined, which is competitive with colorimetric ELISA or with immunoassays based on fluorescent europium chelate labels. The high performance of the method is related to the sensitive ASV determination of gold(III) at a SPE (detection limit of 5 x 10(-9) M) and to the release of a large number of gold(III) ions from each gold particle anchored on the immunocomplex (e.g., 1.7 x 10(5) gold atoms are theoretically contained in a 18-nm spherical gold particle).

Journal Article↗
PubMed2001

Characterization of silane-modified immobilized gold colloids as a substrate for surface-enhanced Raman spectroscopy.

Immobilized gold colloid particles coated with a C-18 alkylsilane layer have been characterized as a substrate for surface-enhanced Raman scattering (SERS) studies of adsorption onto hydrophobic surfaces. Atomic force microscopy images, optical extinction spectra, and SERS measurements are reported as a function of accumulation of gold colloid on glass. As the metal particles become increasingly aggregated on the surface, the SERS enhancement increases until the plasmon resonance shifts to wavelengths longer than the excitation laser. The gold colloid substrates are stable and exhibit reproducible SERS enhancement. When octadecyltrimethoxysilane is self-assembled over the gold, the metal surface is protected from exposure to solution-phase species, as evidenced by the inhibition of chemisorption of a disulfide reagent to the overcoated gold surface. The results show that interactions with gold can be blocked by a silane layer so as not to significantly influence physisorption of molecules at the C-18/solution interface. The SERS enhancement from these C-18-overcoated gold substrates is reproducible for different films prepared from the same colloidal suspension; the substrates are also stable with time and upon exposure to laser irradiation.

Journal Article↗
PubMed2005

Gold nanoparticle-catalyzed luminol chemiluminescence and its analytical applications.

Gold colloids with nanoparticles of different sizes were found to enhance the chemiluminescence (CL) of the luminol-H2O2 system, and the most intensive CL signals were obtained with 38-nm-diameter gold nanoparticles. UV-visible spectra, X-ray photoelectron spectra, and transmission electron microscopy studies were carried out before and after the CL reaction to investigate the CL enhancement mechanism. The CL enhancement by gold nanoparticles of the luminol-H2O2 system was supposed to originate from the catalysis of gold nanoparticles, which facilitated the radical generation and electron-transfer processes taking place on the surface of the gold nanoparticles. The effects of the reactant concentrations, the size of the gold nanoparticles. and some organic compounds were also investigated. Organic compounds containing OH, NH2, and SH groups were observed to inhibit the CL signal of the luminol-H2O2-gold colloids system, which made it applicable for the determination of such compounds.

Journal Article↗
PubMed2000

Electrochemical pretreatment of polycrystalline gold electrodes to produce a reproducible surface roughness for self-assembly: a study in phosphate buffer pH 7.4

It has been emphasized in several studies that the state of the surface, including the surface roughness, is very important for the reproducible formation of high-quality self-assembled monolayers on gold. The pulsed-potential pretreatment procedure described in this paper can, in a reproducible way, reduce the surface roughness of mechanically polished polycrystalline gold electrodes by a factor 2. The developed procedure, in which the gold is alternately oxidized and reduced, has been optimized for use in a flow system (100 mM phosphate buffer pH 7.4). The influence of the pretreatment procedure on the surface roughness of the electrodes has been studied by in-situ oxygen adsorption measurements using cyclic voltammetry. The most effective pulse regime in producing a gold surface with a reproducible and relatively low surface roughness is a triple-potential pulse waveform, with potentials of +1.6, 0.0, and -0.8 Vvs SCE and pulse widths of 100 ms for each potential. Prolonged pulsing for 2000-5000 s with the gold working electrode in a flow-through cell showed an electropolishing effect, i.e., a decrease of the roughness in time. Flow conditions are very important: the roughness decreased faster at higher flow rates, while an increase was observed without flow. A process of reconstruction and dissolution of gold during application of the potential pulses under flow conditions is assumed to account for the observed phenomena. A self-assembled monolayer of thioctic acid with reproducible characteristics, determined with impedance measurements, could be formed on a pretreated gold surface.

Journal Article↗
PubMed2000

Synthesis, structure, luminescence, and theoretical studies of tetranuclear gold clusters with phosphinocarborane ligands.

Treatment of the tetranuclear gold cluster [Au4((PPh2)2C2B9H10)2(AsPh3)2] (1), which contains the nido-carborane-diphosphine [7,8-(PPh2)2C2B9H10]-, with various tertiary phosphines leads to derivatives [Au4((PPh2)2C2B9H10)2-(PR3)2] (PR3 = PPh3 (2), P(4-MeC6H4)3 (3), P(4-OMeC6H4)3 (4)). The X-ray crystal structure of complex 4 shows a tetrahedral framework of gold atoms, two of which are chelated by the diphosphine, and two are coordinated to one monophosphine ligand each. These compounds are very stable and are obtained in high yield. MP2 calculations suggest that the two types of chemically nonequivalent gold atoms can be formally assigned as Au(I) (those attached to the arsines or phosphines) and Au(0) (those bonded to the anionic diphosphine) and emphasize the role of correlation in the gold-gold interactions. The compounds are luminescent. The emission is assigned to a gold-centered spin-forbidden transition; the assignment of the oxidation state of the gold centers on this basis leads to results coincident with those obtained by theoretical calculations.

Journal Article↗