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At least 19 recordsLinked to original sources
PubMed1989

Neuronal imaging with colloidal gold.

Colloidal gold is easily prepared, and readily adsorbs to a number of immunoreagents and other proteins for a wide variety of uses for neuronal visualization. Gold probes serve a role as immunolabels for both light and electron microscopy. As an ultrastructural immunocytochemical marker for detection of proteins, peptides or amino acids, gold can be used for immunostaining thick or thin sections prior to embedding, or for immunostaining ultrathin sections after embedding tissue in conventional or unusual embedding matrices. By virtue of its particulate nature, gold as an immunolabel facilitates a semi-quantitative analysis of relative antigen densities on ultrathin sections. Various combinations of different size gold particles or dual immunolabelling with enzymatic immunolabels together with colloidal gold or silver-intensified gold serve well for ultrastructural immunocytochemical localization of two antigens in the same tissue section. Colloidal gold can be detected with light microscopy, transmission and scanning electron microscopy, and with confocal laser microscopy. Silver intensification allows detection of gold at both the light and electron microscope level, and increases the sensitivity of immunogold procedures. Colloidal gold is useful as a tracer for physiological studies of transport and internalization in neurons in vivo and in vitro; computer-assisted video imaging techniques allow detection and tracking of single gold particles in living cells.

Animals↗
PubMed2004

Resonance light scattering properties of Eu3+ in gold colloid.

Gold colloidal containing rare-earth ions Eu3+ were prepared at room temperature. Fluorescence spectra and resonance light scattering (RLS) spectra of Eu3+ ions and gold colloid containing Eu3+ were measured. For solution containing Eu3+, RLS features show two peaks at the edges of the visible light wavelength region. The short wavelength peak takes place at about 400 nm and the longer wavelength peak is the corresponding 1/2 fraction frequency RLS peak, which takes place at about 780 nm. When gold colloids were added to the solution containing Eu3+, both these two RLS peaks were enhanced. We believe that the energies, which are absorbed by the surface plasmon resonance in the gold nanoparticles, are efficiently transferred into the Eu3+ ions to cause the increased scattering.

Cations↗
PubMed1984

Ultrastructural localization of rotavirus antigens using colloidal gold.

Colloidal gold was used to localize six of the ten known proteins of the simian rotavirus SA11 within infected cells by ultrastructural immunocytochemistry. Monospecific or monoclonal antibodies to selected structural and nonstructural proteins were the primary antisera. The major outer capsid glycoprotein, VP7, was associated with nonenveloped particles, with particles de-enveloped by Triton X-100 and with both nuclear and cytoplasmic inclusions. The protease-sensitive outer capsid protein, VP3, was also found on nonenveloped and de-enveloped particles. The major inner capsid protein, VP6, was accessible to antibodies on some of the nonenveloped particles (presumably single-shelled particles) and on the de-enveloped particles. A monospecific antibody to the gene 11 product, believed to be a precursor to a minor structural protein, VP9, reacted strongly with viroplasmic inclusions. Virus particles were weakly labeled by this antibody. NS35, a nonstructural SA11 protein, was found only in the viroplasms. NS29, a nonstructural glycoprotein, was localized to the cytoplasmic side of the endoplasmic reticulum membrane and to the inside of enveloped virus particles. These data support the hypothesis that NS29 facilitates budding of the virus particles and acquisition of the outer capsid layer.

Animals↗
PubMed1992

Transport of particles of colloidal gold within and from rat lung after local deposition by alveolar microinjection.

Because inhalation and intratracheal instillation deposit particles throughout the respiratory tract, these methods of administration give little information on the movement of particles within the lung and no direct information on the clearance kinetics from locally defined sites within alveolar tissue. Approximately 0.05 microL of 195Au-labeled gold colloid was administered to 32 rats by microinjection into a small volume of subpleural alveoli. Its fate was studied by whole-body counting and serial sacrifice over 15 months. The kinetics of clearance from the subpleural deposition site showed that there was no rapid removal of particles, and the main clearance process was defined by an exponential term with a half-time averaging 583 days. There was a wide variation between individual animals. The distribution of 195Au at sacrifice showed that the gold colloid was nearly all retained within the respiratory tract. The particles were not appreciably redistributed throughout the lung volume, so most of the material not cleared from the lung remained close to the deposition site. At the later times after microinjection, much of the gold colloid was associated with thickened pleura and adjoining septae.

Animals↗
PubMed1984

Platelet-derived growth factor labeled to colloidal gold for use as a mitogenic receptor probe.

Studies by others utilizing 125I-PDGF have indicated that target cells express a high affinity surface receptor for PDGF. We have bound purified platelet-derived growth factor (PDGF) to gold colloid particles to explore the interaction of PDGF with mouse 3T3 cells. The gold-PDGF complex consists of approximately 26 PDGF molecules electrostatically absorbed to gold colloid (approximately 14.1 nm). The gold-PDGF complex induced mitogenic stimulation similar to unbound PDGF, although a 5 to 6 fold greater amount of complexed PDGF was required for the same effect. Incubation of the gold-PDGF complex with 3T3 cells for 4 h at 4 degrees C revealed that 98% of the membrane binding was randomly distributed on the cell surface with respect to coated pits, with each cell binding 7000 to 11000 complexes. Addition of a 20-fold excess of unlabeled PDGF reduced surface binding of the gold-PDGF complex by 87% (1230 probes/cell). Warming to 37 degrees C followed by time-interval fixation permitted visualization of endocytosis of the complexes in coated vesicles (1-3 min), internalization (3-15 min) and lysosomal accumulation (15-60 min). Pretreatment of cultures with monensin (2 h, 10 microM) abolished receptor binding, internalization and subsequent mitogenesis of the gold-PDGF complex. These studies support the suggestion that PDGF requires a surface receptor to elicit mitogenesis.

Animals↗
PubMedDate not supplied

On the preparation, characterization, and enzymatic activity of fungal protease-gold colloid bioconjugates.

We present herein details pertaining to the preparation of bioconjugates of colloidal gold with aspartic protease from the fungus Aspergillus saitoi (F-prot) and their characterization and enzymatic activity. Simple mixing of the colloidal gold and protein solutions under protein-friendly conditions (pH = 3) followed by centrifugation (to remove uncomplexed gold nanoparticles and protein molecules) results in the formation of the fungal protease-gold nanoparticle conjugates. The protein-gold nanoparticle bioconjugate was redispersed in buffer solution and indicated the formation of efficient bioconjugates with intact native protein structures. The bioconjugates in solution were characterized by UV-vis spectroscopy, fluorescence spectroscopy, and biocatalytic activity measurements while drop-dried bioconjugate films on Si (111) substrates were characterized by scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX), and X-ray diffraction (XRD) measurements. Microscopy images do show some aggregate formation, but the intactness of the native structure of the enzyme in the bioconjugate material was verified by fluorescence and biocatalytic activity measurements. The enzyme retains substantial biocatalytic activity in the bioconjugate material and was comparable to that of free enzyme in solution.

Aspartic Acid Endopeptidases↗
PubMed1982

Effects of particle size and perfusate composition on the uptake of colloidal gold by the rabbit thoracic aorta perfused in situ.

The influence has been investigated of particle size on the uptake of radioactive gold colloid by the rabbit thoracic aorta perfused in situ. Particles ranging in diameter from 14 nm to 40 nm were suspended in 0.9% NaCl and infused either at a pressure of 15 mm Hg for times of between 2 1/2 and 60 min or at pressure of between 15 and 160 mm Hg for 5 min. Uptake by the whole intima-media increased with perfusion time and hydrostatic pressure but did not depend on particle size. Radioactive assay of serial sections across the aortic wall also showed that particle size did not influence the distribution of tracer. An effect of perfusate composition on uptake was demonstrated in further experiments in which particles either 14 or 40 nm in diameter were suspended in pooled rabbit serum and infused at pressures of between 15 and 140 mm Hg for 5 min. Uptake and transmural distribution were again independent of particle size, but uptake was 4-5-fold less than when the particles were perfused in saline. Under all perfusion conditions radioactivity fell steeply across the intima and then rose gradually across the media and adventitia. Radioactivity in the outer media and adventitia increased with perfusion time but little change could be detected in intimal activity. In transmission electron micrographs, particles in the intima were not seen to penetrate the internal elastic lamella and in the outer media particles remained extracellular and did not enter collagen bundles. Autoradiographs showed that particles in the intima were uniformly distributed around the circumference of the vessel but in the outer media and adventitia particles usually clustered close to the vasa vasorum.

Animals↗
PubMed2004

Electrophoretic properties of DNA-modified colloidal gold nanoparticles.

Oligonucleotide-modified gold nanoparticles are used in various kinds of colorimetric DNA targeting biosensors and nanoparticle assembly techniques. Herein we focus on how the size of 13 nm gold colloids changes upon DNA modification. We have performed a series of electrophoresis experiments of particles modified both thiol specifically and nonspecifically with single- and double-stranded oligonucleotides of different lengths (12- and 25-mers). Both unmodified and DNA-modified particles migrated at constant velocity in different concentrations of Metaphor agarose gels. Linear Ferguson plots were obtained for all samples, and on the basis of the Ogston model approach, we present how the particle size increases in different amounts depending on the oligonucleotide length, secondary structure, and type of modification (specific or nonspecific). Thiol specifically modified particles obtain a thicker DNA layer since the oligonucleotides are only anchored to the particle in one end and thus stand up from the surface more compared to nonspecifically modified ones, where the oligonucleotides tend to lay more or less flat on the surface with multiple adsorption points. However the thickness of the DNA layer for the thiol specifically modified particles is smaller than the length of a corresponding stretched oligonucleotide, suggesting a flexibility of the thiol-bound strands allowing them to tilt relative to the particle surface.

Electrophoresis↗
PubMed1991

Suitability of different silver enhancement methods applied to 1 nm colloidal gold particles: an immunoelectron microscopic study.

In order to exploit the recently introduced 1 nm gold colloids in routine electron microscopic labeling experiments, an efficient enhancement step for a better visualization of this small marker is a prerequisite. Efficiency and reproducibility of enhancement as well as growth homogeneity of gold particles were evaluated for three different silver intensifying solutions: silver lactate/hydroquinone/gum arabic (Danscher, 1981), Ilford L4/Metol (Bienz et al., 1986), and the commercially available IntenSE M silver enhancement kit (Janssen Pharmaceutica). The best results were obtained by using the silver lactate/hydroquinone/gum arabic mixture. The quality of enhancement of the IntenSE M kit was considerably increased by the addition of the protective colloid gum arabic.

Bacterial Outer Membrane Proteins↗
PubMed1996

The silver anniversary of gold: 25 years of the colloidal gold marker system for immunocytochemistry and histochemistry.

Since 1971, when W.P. Faulk and G.M. Taylor published "An immunocolloid method for the electron microscope", colloidal gold has become a very widely used marker in microscopy. It has been used to detect a huge range of cellular and extracellular constituents by in situ hybridization, immunogold, lectin-gold, and enzyme-gold labeling. Besides its use in light microscopic immunogold and lectin-gold silver staining, colloidal gold remains the label of choice for transmission electron microscopy studying thin sections, freeze-etch, and surface replicas, as well as for scanning electron microscopy. The year 1996 is the 25th anniversary of the introduction of colloidal gold as a marker in immunoelectron microscopy and this overview outlines some of the major milestones in the development of the colloidal gold marker system.

Animals↗
PubMed2000

Conductimetric membrane strip immunosensor with polyaniline-bound gold colloids as signal generator.

For point-of-care examination, an immuno-chromatographic assay system based on conductimetric detection was investigated by utilizing, as signal generator, colloidal gold with polyaniline bound on the metal surface. Although the gold is a widely used label for antibodies to produce colorimetric signals, the tracer does not lend itself for a suitable electric conduction along the gold particles due to the presence of protein barriers (e.g. immunoglobulin and blocking agent) against electron transfer. To overcome this problem, we introduced a conducting polymer, for instance, polyaniline, as a conductivity-modulating agent on the gold surface after immobilizing an antibody specific to human albumin used as model analyte. This novel signal generator amplified the conductimetric signal 4.7 times compared with the plain gold, and the signal was also maximum 2.3-fold higher than that from the photometric system under the same analytical conditions. The latter effect resulted from an exponential pattern in the dose-response curve of the electric signal that was different from the conventional sigmoidal shape.

Aniline Compounds↗
PubMed1980

A review of the colloidal gold marker system.

Colloidal gold can be used as a particulate marker for the detection and localization of target molecules by various modes of microscopy (light and fluorescent microscopy, scanning and transmission electron microscopy) using both direct and indirect labeling approaches. Several techniques are available for the preparation of gold markers in a size range of 5nm to 150nm, their mean size and shape characteristics and absorption spectra varying with particle size. Under appropriate conditions, colloidal gold will bind macromolecules by non-covalent electrostatic adsorption with little change in the specific activity of the bound macromolecule. This interaction is influenced by a number of factors including ionic concentration, pH conditions (in correlation with the protein pI values) and protein stabilizing levels. Presence of reactive protein on probes can be demonstrated and quantitated by direct and indirect radioactive binding assays and agglutination assays. These assays provide convenient procedures for characterizing stability, and behaviour in storage, of gold probes. Stability of gold probes under conditons where competing proteins are present, under freeze-thaw cycles and under SEM preparation conditions have been evaluated in this paper. Some of the basic procedures in the application of gold probes to cell labeling are briefly discussed together with certain limitations of the colloidal gold marker system. A bibliography of gold probe cell labeling studies is included.

Animals↗
PubMed1992

Cationic colloidal gold--a probe for light- and electron-microscopic characterization of acidic glycoconjugates using poly-L-lysine gold complex.

Cationic colloidal gold (CCG) was used to characterize acidic glycoconjugates in semithin and ultrathin sections of rat large intestine and salivary glands embedded in hydrophilic Lowicryl K4M resin. It was prepared from poly-L-lysine and 10 nm colloidal gold solution. The staining of CCG in semithin sections was amplified after photochemical silver reaction using silver acetate as a silver ion donor and examined under bright-field and epi-illumination microscopy. CCG adjusted to various pH levels was tested on various rat tissues whose histochemical characteristics with regard to acidic glycoconjugates are well known. At pH 2.5 CCG labelled tissues containing sialylated and sulphated acidic glycoconjugates such as the apical cell surface, mucous cells in the distal and proximal colon, and acinar cells of the sublingual gland. In contrast, CCG at pH 1.0 labelled tissues containing sulphated acidic glycoconjugates such as mucous cells in the upper crypt of the proximal colon and mucous cells in the whole crypt of the distal colon. This specificity of CCG was verified by the alteration of CCG staining following several types of cytochemical pretreatment. These results were further confirmed by electron microscopy. CCG staining is thus a useful postembedding procedure for the characterization of acidic glycoconjugates at both the light- and electron-microscopic levels.

Cations↗