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PubMed1987

Solid core liposomes with encapsulated colloidal gold particles.

Solid core liposomes with encapsulated colloidal gold particles were prepared through four major steps: Preparation of prevesicles with encapsulated solid cores of agarose-gelatin by emulsification of agarose-gelatin sol in organic solvent containing emulsifiers followed by cooling. Extraction of lipophilic components from prevesicles to obtain microspherules of agarose-gelatin. Introducing colloidal gold particles into microspherules and coating with protein molecules. Encapsulation of colloidal gold-bearing microspherules with the modified organic solvent spherule evaporation method for preparation of liposomes (Kim et al. (1983) Biochim. Biophys. Acta 728, 339-348 and Kim et al. (1984) Biochim. Biophys. Acta 812, 793-801). Electron micrographs showed that if liposomes were prepared by using a lipid mixture containing dioleoylphosphatidylcholine/cholesterol/dioleoylphosphatidylglycerol/tri olein (molar ratio 4.5:4.5:1:1), there was only a single continuous bilayer membrane for each solid core liposome. However, if no triolein was added to the lipid mixture, it would cause the formation of multilamellar liposomes. In both cases, there were hundreds to thousands of colloidal gold particles within each solid core liposome.

Cholesterol↗
PubMed2003

Colloidal gold submonolayer-coated thin-film glass plates for waveguide-coupled surface plasmon resonance sensors.

A novel optical sensor based on spectroscopic measurement of the plasmon absorption of a colloidal gold submonolayer immobilized upon a planar waveguide has been developed for label-free detection of biomolecular interactions at the sensor's surface. We fabricated the sensor by locally modifying a 50-microm-thick glass plate with hemoglobin (Hb) and then self-assembling gold colloids from the aqueous solution onto the Hb-modified area of the glass plate. Polychromatic light from a xenon-arc lamp was launched into the thin-film glass plate by use of a broadband fiber-coupling method. With the use of a CCD detector to monitor the light beam emitted from an end face of the glass plate, the plasmon absorption spectrum of the colloidal gold submonolayer was determined to depend on the polarization states of the guided light and to change with the refractive index of the medium in contact with the colloids. In addition to simplicity of fabrication and the ease of use, the sensor yields a larger absorbance sensitivity than the normal transmission measurement.

Journal Article↗
PubMed1986

Cationic colloidal gold--a new probe for the detection of anionic cell surface sites by electron microscopy.

Particles of colloidal gold were coated with poly-L-lysine to prepare cationic colloidal gold. Monodispersed colloidal gold with a particle diameter of 5, 8, or 15 nm and poly-L-lysine with a molecular weight of 350,000 or 1500-8000 were used. The resulting complexes were used to label red blood cell membranes. The labeling was sensitive to neuraminidase treatment or acid hydrolysis, demonstrating that cationic colloidal gold binds preferentially to anionic cell surface constituents. Cationic colloidal gold can be used at physiological pH values and ionic strength, as well as at low pH values, making it a flexible probe for detection of anionic cellular components.

Erythrocyte Membrane↗
PubMedDate not supplied

Use of colloidal gold in diagnostic surgical pathology.

Colloidal gold immuno-electron microscopy is a powerful tool for defining antigenicity at the subcellular level. Such studies permit correlation with cell fractionation studies. They also allow one to assess the specificity of a particular antibody. The most useful reagent for immuno-electron microscopy is colloidal gold stabilized by a binding protein, either staphylococcal protein A or immunoglobulin. This method permits highly discrete labeling, and the system is useful for most antibodies used in diagnostic pathology.

Antigens↗
PubMed1999

Kinetic Study on the Formation of Colloidal Gold in the Presence of Acetylenic Glycol Nonionic Surfactant.

The formation of colloidal gold was kinetically studied using the monomer or micelle form of the acetylenic glycol nonionic surfactant Surfynol 465, which functions as a reducing and stabilizing agent. When two equal volumes of aqueous solution of Au(III) and Surfynol 465 were mixed, absorbance at the peak around 300 nm due to Au(III) rapidly decreased with time exponentially. A new peak began to appear around 530 nm, whose height sigmoidally increased with time, showing the formation of colloidal gold. From the variation in absorbance at 300 or 530 nm with time, colloidal gold formation would appear to occur through consecutive first-order reactions, Au(III) --> Au(I) --> Au(0) --> gold particle, for monomer and micelle systems. As for Au(I), the complex between Au(I) and &bond;C&tbond;C&bond; of Surfynol 465 was assigned based on reactions previously proposed for the Raman spectra of colloidal gold (Sato, S., Colloid Polym. Sci. 274, 1161 (1996)). The reaction, Au(0) --> gold particle, proceeded quickly. The overall rate of reaction was slower in the micelle system than in the monomer system. For both systems, the rate constant of the reaction Au(III) --> Au(I) exceeded the constant of the reaction Au(I) --> Au(0), and the activation energies of the two reactions were 58 kJ mol(-1). From the agreement with the activation energy of formation of colloidal gold by another method, consecutive first-order reactions, Au(III) --> Au(I) --> Au(0) --> gold particle, were considered valid for the formation of colloidal gold in the presence of Surfynol 465. Copyright 1999 Academic Press.

Journal Article↗
PubMed2004

Resonance light scattering spectroscopy study of interaction between gold colloid and thiamazole and its analytical application.

In this paper, we used resonance light scattering (RLS) spectroscopy to study the interaction between thiol-containing pharmaceutical-thiamazole and gold colloid. At pH 5.2, the resonance light scattering spectrum of gold nanoparticles has a maximum peak at 555 nm and the RLS intensity is enhanced by trace amount of thiamazole due to the interaction between thiamazole and gold colloid. The binding of colloidal gold to thiamazole results in ligand-induced aggregation of colloidal gold, which was characterized by RLS spectrum, ultraviolet-visible (UV-Vis) spectrum, and transmission electron microscopy (TEM). Based upon the study, we proposed a highly sensitive, gold colloid-based assay using RLS spectrum to detect pharmaceuticals for the first time. The mechanism of binding interaction between Au colloid and thiamazole was also discussed.

Absorption↗
PubMed1983

Colloidal gold: a pluripotent receptor probe.

Colloidal gold is an electron-dense, lyophobic colloid that readily forms a stable electrostatic interaction with a variety of macromolecules. Monodispersed colloids ranging from 3-150 nm in diameter can be produced to provide the researcher with flexibility in selecting the optimally sized probe. Gold labeling of antibodies and lectins has been extensively used to study surface antigens and cell components. Recently, the use of gold labeling has been extended to study receptor-ligand binding, enzyme-substrate reactions, and transcellular pathways. Published applications include gold labeling of metabolites (low-density lipoproteins), enzymes (DNAase and RNAase, RNA polymerase, thrombin, collagenase, elastase), hormones (insulin, epidermal growth factor, glucagon), circulating plasma proteins (asialoglycoprotein, alpha 2-macroglobulin, factor VIII-von Willebrand factor), and endotoxins (tetanus toxin, cholera toxin). This broad spectrum of applications emphasizes the versatility and usefulness of colloidal gold as a probe in areas of cell biology related to receptors, endocytosis, transport, and functions of proteins.

Animals↗
PubMed1990

Analysis of colloidal gold probes by isoelectric focusing in agarose gels.

Colloidal gold particles of different size (3-20 nm in diameter) were prepared by tannic acid-citrate and citrate reduction methods. From these colloids, different probes were prepared using sheep anti-rabbit antiserum, sheep anti-rabbit IgG, bovine serum albumin, polyethylene glycol, and protein A as the primary stabilizers and polyethylene glycol and/or bovine serum albumin as secondary and tertiary stabilizers, in different combinations. The probes were analyzed by isoelectric focusing in agarose gels, which allow the migration of particles in the size range 3-20 nm. (P. Sewer and S. J. Hayes, 1986, Anal. Biochem. 158, 72-78). Isoelectric focusing revealed that the surface charge of colloidal gold probes is dependent upon the size of the gold particle, the reduction method used, the primary ligand, and the pH at which this is adsorbed, as well as upon the secondary and tertiary stabilizers used. It is proposed that such differences in surface charge may underlie the different results which may sometimes be observed in colloidal gold labeling, especially when novel ligands are used.

Colloids↗
PubMed2000

Applications of gold cluster compounds in immunocytochemistry and correlative microscopy: comparison with colloidal gold.

In this review, we discuss the immunocytochemical literature with respect to a comparison between conventional colloidal gold and gold cluster compounds as immunoprobes. The relative advantages and disadvantages of each of these types of particle for immunocytochemical applications are discussed. We present results from our own laboratories and those of others on the comparison of these immunoprobes in selected experimental situations. These results show the use of gold cluster compounds at both light and electron microscope levels. At the ultrastructural level, gold cluster compounds have been used in pre-embedding labelling of cultured cells, and for labelling of ultrathin cryosections and freeze-fracture preparations. Recently, fluorescently tagged gold cluster compounds have become available. Using ultrathin cryosections of human neutrophils as a model system, we demonstrate that a single immunoprobe (i.e. a fluorescently tagged gold cluster compound) is a robust probe for correlative fluorescence and electron microscopy.

Gold Colloid↗
PubMed1991

[A new method for immunological detection of fecal blood, using colloidal gold labeled with anti-human hemoglobin monoclonal antibody].

Application of colloidal gold agglutination to detection of fecal blood was done. Colloidal gold labeled with monoclonal antibody recognized human hemoglobin was agglutinated with hemoglobin and changed the color from red to gray. The color that diminished rapidly with an antigen was unchangeable from 30 min to 4 hr. Reaction was single step, and positive tests were easily distinguished from negative tests. Detectable hemoglobin concentration was 0.5 micrograms/ml. Comparison of colloidal gold agglutination with other methods, as low as latex agglutination and RPHA, showed good agreements in 1409 fecal samples. Colloidal gold agglutination method is superior in easiness of judgement and unnecessity of keeping time, and will be suitable for mass screening for colorectal cancer using 96 well microplate.

Agglutination Tests↗