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PubMed1988

The effect of three variables on adsorption of rabbit IgG to colloidal gold.

The purpose of this investigation was to (a) begin to evaluate the coagulation curve as a means of selecting the minimal quantity of IgG required to stabilize colloidal gold (Au); (b) determine the effect of the quantity of IgG added, the pH of adsorption, and the isoelectric point (pI) range of the IgG on the quantity of IgG bound and the stability of the IgG-Au complex with respect to desorption; and (c) discuss these results with respect to current theory on the effect of pH on adsorption of IgG to surfaces. No absolute minimal value required to prevent coagulation could be determined despite the high reproducibility of the values obtained; approximate values were selected. Each variable had an effect on the quantity of IgG bound: as the quantity of IgG added increased, the quantity bound increased; as the pH of adsorption became more alkaline, the quantity bound decreased; and as the pI range of the IgG became more alkaline, the quantity bound increased. IgG-Au complexes with a variable number of bound IgG molecules, depending on the three variables selected, can be produced. Production of IgG-Au composed of uniform numbers of IgG is discussed. A modification of the current theory on the effect of pH on adsorption of IgG is proposed.

Adsorption↗

PubMed1991

Visualization of nimodipine (NIM) binding sites of rat brain by means of a NIM-colloidal gold complex (1-2).

It is described a new method to visualize the binding sites of the Ca(2+)-antagonist nimodipine (NIM) on brain cryostatic sections. NIM was bridged to colloidal gold sols by a suitable amphophilic detergent, and used according to autoradiographic procedures. A detailed mappage of vascular and neuronal NIM binding sites was allowed by silver-intensification of the NIM-gold complex bound to the nervous tissue. Selective distribution patterns were visualized in the main cerebral and cerebellar areas, suggesting that the drug potentially may act on multiple, different targets in the CNS.

Animals↗

PubMedDate not supplied

Photoelectron microscopy of erythrocyte ghosts: imaging of lectin binding sites with colloidal gold markers.

Images of human red cell ghosts have been obtained by photoelectron microscopy (photoemission electron microscopy or PEM) without any staining, metal coating or shadowing. Membrane folding, when it occurs in these collapsed structures, shows up clearly even though the membrane itself is only 5-10 nm in thickness. Using red cell ghosts as a model system, it is shown that colloidal gold can act as a photoemissive marker. Specific lectin binding sites on the cell surface were labeled with a colloidal gold-wheat germ agglutinin complex. The gold particles were readily detectable against the weaker emission from the cell surface.

Colloids↗

PubMed2005

Colloidal gold nanoparticle modified carbon paste interface for studies of tumor cell adhesion and viability.

A non-toxic biomimetic interface for immobilization of living cells and electrochemical exogenous effect study of cell viability was constructed by mixing colloidal gold nanoparticles in carbon paste. A new approach to study the effects of anti-tumor drug and other exogenous factors on cell viability was proposed. The nanoparticles were efficient for preserving the activity of immobilized living cells and preventing their leakage from the electrode surface. The immobilized living AsPC-1 cells (pancreatic adenocarcinoma cells derived from ascites) exhibited an irreversible voltammetric response related to the oxidation of guanine. The presence of guanine was verified by liquid chromatography-mass spectrometry. The contents of guanine in cytoplasm of each AsPC-1 and normal pancreatic cell were detected to be 370 and 22amol, respectively. The cytotoxic effect of adriamycin resulted in a decrease in peak current of guanine. The optimal exogenous factors that affected cell viability, including pH, temperature and salt concentration of electrolyte, were just consistent with cell growth conditions in culture. This simple and rapid method could be applied for the electrochemical investigation of exogenous effect and characterization of the viability of living cells.

Antineoplastic Agents↗

PubMed1991

[The use of RNAse A-colloidal gold complexes for research on RNA-containing cell structures: the effect of different factors on the specificity of the labelling].

Effects of various factors on the specificity and intensity of labelling of RNA-containing structures on the ultrathin sections by RNase A--colloidal gold complexes were studied. The data obtained show that at the optimal choice and standard conditions of labelling the reproducibility of the results is achieved up to 10-20%. It makes it possible to use RNase A-gold method for the quantitative analysis of RNA distribution in the cells at various stages of cell cycle.

Animals↗

PubMed1981

alpha 2-macroglobulin adsorbed to colloidal gold: a new probe in the study of receptor-mediated endocytosis.

alpha 2-Macroglobulin (alpha 2 M) was adsorbed to colloidal gold and used as a new tool in the study of receptor-mediated endocytosis. alpha 2 M-gold is easy to prepare and is clearly visualized at the electron microscope level. When cells were incubated with alpha 2 M-gold at 0 degrees C, gold was visualized both diffusely over the cell surface and concentrated in coated pits. After cells to which alpha 2 M-gold had been bound at 0 degrees C were warmed, the gold was rapidly internalized into uncoated vesicles, previously termed receptosomes. After 30 min of incubation or longer, gold was found in small lysosomes and, later, in large lysosomes and very small vesicles in the region of the Golgi complex. This pattern of localization is similar to that previously described, using peroxidase-labeled anti-alpha 2 M antibodies. By incubating cells with both alpha 2 M-gold and vesicular stomatitis virus (VSV), we studied the internalization of these two markers simultaneously. VSV and alpha 2 M-gold rapidly clustered in the same coated pits and were internalized in the same receptosomes. Proteins and hormones adsorbed to gold may be useful in the study of receptor-mediated endocytosis.

Animals↗

PubMed2003

Enhanced photostability of ICG in close proximity to gold colloids.

Photobleaching of fluorophores frequently limits their detectability or observation time. We examined Indocyanine green (ICG) which is widely used in medical testing and is highly unstable. We showed that spatial localization of ICG near metallic gold colloids resulted in increased photostability. This suggests the use of fluorophore-metal conjugates in situations adversely affected by photobleaching.

Gold Colloid↗

PubMed1993

Assay of D-dimer based on immunofiltration and staining with gold colloids.

In this immunofiltration assay of D-dimer in plasma samples, the antigens are captured by a monoclonal antibody on a porous membrane, and labeled with the same antibody conjugated to gold colloids. The assay time is < 2 min, and a color of intensity proportional to the concentration of D-dimer is left on the membrane. The reference range (mean +/- 2 SD) was 0.336 +/- 0.133 mg/L (n = 69). Linearity was found up to 10 mg/L. Comparison with ELISA results (x) for 198 patients' samples demonstrated a linear regression equation of y = 0.99(+/- 0.05)x + 0.68(+/- 0.07) and a mean square error of 0.503. Comparison of visual reading of the color signal (y) vs reflectometric measurements (x) for 220 patients' samples demonstrated a linear regression equation of y = 2.5(+/- 0.06)x -0.22(+/- 0.04) and a mean square error of 0.095. Bilirubin, hemoglobin, fibrinogen, soluble fibrin, and fibrinogen degradation products and freezing/thawing of samples did not interfere. Some interference from rheumatoid factor, heparin, and the presence of cells or large lipid particles was seen. The variance (CV) was 8-12% within run, 10-18% between runs, and 13-20% between persons. The new assay constitutes a rapid and reliable analytical tool combining simplicity equivalent to that of latex tests with analytical information approaching that of ELISA.

Drug Stability↗

PubMed1997

Optical slicing and 3-D characterization of hippocampal capillaries in the rat visualized by autometallographic silver enhancement of colloidal gold particles.

In order to visualize the vascular system of the rat brain, 10 Wistar rats were perfused transcardially with glutaraldehyde and a 40 degrees C gold-gelatine solution. The brains were post-fixed with glutaraldehyde and vibratomized into 100-micron-thick slices, and the gold particles were developed by autometallography. In this way, the colloidal gold particles in the vessels became encased in silver and thereby made visible. The developed gold staining is stable and does not interfere with further dehydration and counterstaining. Images were frame grabbed during optical slicing, and classic stereograms and 'shadow' 3-D images were produced. We found a high variation of capillary density in the hippocampal region reflecting known subregional structures. The silver-enhanced vessels acted as natural markers and made it possible to study and measure aspects of the complexity of dehydration and staining artifacts. We found a non-linear shrinking of 13-17% in the x- and y-directions and a spatial shrinking up to 50% in some regions after the dehydration and staining process. This observation may be of interest not only in relation to tissue subjected to this fixation protocol but also to other fixation procedures. The gold-gelatine autometallographic technique and the present stereograms can release data for stereological use as well.

Animals↗

PubMed1982

An electron microscopic demonstration of immune complexes of hepatitis B e-antigen using colloid gold as a marker.

Immune complexes of the hepatitis B e-antigen (HBeAg) could be labeled and thus visually identified in the electron microscope by using antibody to HBeAg (anti-HBe) tagged with colloidal gold particles. Circulating immune complexes of HBeAg were detected in sera from patients with acute hepatitis B infections as well as from asymptomatic carriers of hepatitis B surface antigens (HBsAg). Sera positive for rheumatoid factor frequently contained mixed aggregates in which immune complexes of HBsAg were closely bound to immune complexes of HBeAg.

Antibodies, Viral↗

PubMed1981

Binding of bovine factor VIII-coated colloidal gold particles to receptors on platelet membranes.

Bovine factor VIII/platelet aggregating factor was adsorbed into gold granules and the protein-gold complex added to either formalin-fixed or fresh washed human platelets. Following aggregation, binding of gold granules to the platelets was measured by monitoring the optical density of colloidal gold remaining in the supernatant. Scatchard analysis of binding data indicated that multiple classes of binding sites were present. The number of high affinity binding sites per formalin-fixed platelet depended on the concentration of ristocetin: 420 gold granules were calculated to bind at 1.4 mg/ml of ristocetin, 610 at 0.6 mg/ml of ristocetin and 875 when no ristocetin was added. Fresh washed platelets bound 1350 granules per cell in the absence of ristocetin. We conclude that during platelet aggregation, induced by bovine factor VIII, the binding sites on the platelet surface are only partially occupied.

Animals↗

PubMed1989

[An experimental investigation on application of silver-intensification technique to immunoelectron microscopy with colloidal gold probe].

The value of silver-intensification technique to immunoelectron microscopy being displayed with colloidal gold probe was evaluated through ultrastructural study on localization of cardionatrin in the atrial cardiocytes of rat. The results indicate that this technique is simple and feasible. It enables rapid screening of positively labelled sites at low magnification, and more information will be available. Further more, it offers better contrast and this technique may be of practical value.

Animals↗

PubMed1984

[Relation of proliferating to nonproliferating spleen cell populations during the development of Rauscher leukemia and after loading the mononuclear phagocyte system with colloidal gold].

Undulatory changes in the ratio of proliferating to quiescent spleen cells of (C57BL/6j X DBA/2)F1 male mice were revealed in the course of Rauscher's leukemia development by means of nucleoprotein-celite chromatography. Administration of colloidal gold particles for the purpose of the functional loading of the mononuclear phagocyte system (MPS) induced a temporary diminution (for several hours) of the proliferating cell percentage and the DNA synthesis rate. Then the number of proliferating cells returned to normal (by 24 hours), with the DNA synthesis rate exceeding the basic level. The data obtained point to the dependence of tumor cell proliferation on the MPS in Rauscher's leukemia.

Animals↗

PubMed1988

Bioapplication of colloidal gold in microbiological immunocytochemistry.

Microbiological organisms are an ubiquitous group of animals encompassing bacteria, viruses, protozoa, algae and fungi. They are adapted for survival in many diverse habitats and exert a profound effect on man and his environment. Colloidal gold electron immunocytochemistry is a useful technique for studying these organisms and may be applied in several ways. The post-embedding technique is used to detect internal antigens, whilst the pre-embedding technique is employed for the detection of external antigens. In contrast the immuno-negative stain technique is applied to detect antigens on structures such as viruses or bacterial pili which may be dried down onto an electron microscope grid and immunolabelled in situ. In addition the immunoreplica technique allows the examination of cell surfaces for the appearance of antigens. Together these techniques have yielded valuable information concerning microbiological organisms.

Bacteria↗

PubMed1976

The effect of colloidal gold on blood coagulation.

Coagulation tests were carried out in rabbits after the intravenous administration of 2 mg/kg colloidal gold. Among the clotting factors, platelet Factor 3 and Factor XIII were found to be inhibited by the gold preparation. Gold at 2 mg/ml concentration induced an overall antithrombotic state in spite of an increased tendency to platelet aggregation. These experiments suggest a new possibility for the inhibition of Factor XIII and platelet Factor 3.

Animals↗

PubMed1990

Colloidal gold immunolabeling of immunoglobulin-binding sites and beta antigen in group B streptococci.

We have characterized the immunoglobulin A (IgA)-Fc-binding properties and beta-antigen expression of several strains of group B streptococci by using ultrastructural immunocytochemistry. Colloidal gold-labeled tracers were used with intact and sectioned bacteria in order to gain information regarding the location and distribution of cell surface and cytoplasmic IgA-Fc-binding molecules and beta antigen. Colloidal gold (5- or 15-nm particles) was conjugated to IgA to characterize IgA-binding properties and to IgG to test for IgG binding. Rabbit anti-beta antiserum was reacted with the bacteria and then with protein G labeled with 15-nm colloidal gold particles. A double-labeling technique was used for simultaneous localization of IgA-Fc- and anti-beta-antibody-binding properties on sectioned bacteria. The data corroborated previous results which indicated that (i) IgA-Fc-binding and IgA-Fc-nonbinding forms of beta antigen can be secreted by strains which do not express beta antigen on the cell surfaces (HG806, VC75); (ii) differences in levels of expression of beta antigen and/or IgA-Fc-binding proteins can be detected among various group B isolates; (iii) group B streptococci do not express human IgG-Fc-binding proteins; and (iv) not all forms of beta antigen are capable of binding human IgA.

Animals↗

PubMed1991

Simultaneous visualization of chromosome bands and hybridization signal using colloidal-gold labeling in electron microscopy.

Electron microscopy (EM) is seldom used with in situ hybridization to localize DNA sequences because banding methods for chromosome identification could not be coupled to EM techniques. We have applied an immunochemical replication-banding method specific for EM to solve this problem. A thymidine synchronization/BrdUrd release protocol allows BrdUrd incorporation only into late replicating bands. A biotinylated DNA probe is hybridized in situ to its complementary sequence. The biotinylated probe and the BrdUrd-substituted DNA are simultaneously localized by different reporter/detection systems using different-sized colloidal gold particles as electron-dense tags. We demonstrate the high precision of this mapping procedure by localizing on long prophase chromosomes (greater than 1000 bands per haploid set) the pXBR-1 sequence to a small subregion of the centromeric subband Xp11.1-Xq11.1. This localization to a part of an individual prophase subband is the most precise localization ever reported on human banded mitotic chromosomes.

Cells, Cultured↗

PubMed1988

Location and identification of colloidal gold particles on the cell surface with a scanning electron microscope and energy dispersive analyzer.

The use of colloidal gold particles for locating cell surface components by scanning electron microscopy (SEM) has been restricted due to difficulties in the identification of these gold particles under SEM. It is shown here how the gold particles bound to cell surfaces can be located and identified under SEM using the secondary electron imaging (SEI) mode with an energy dispersive X-ray microanalyzer (EDS). This enables reliable identification of gold particles and good quality micrographs of the cells to be achieved at the same time. The distribution of receptors for two lectins, concanavalin A (ConA) and wheat germ agglutinin (WGA), on the surface of cultured Raji cells and human erythrocytes is presented as an example. Raji cells and erythrocytes were fixed with glutaraldehyde, post-fixed with a glutaraldehyde-tannic acid mixture and then incubated with ConA- or WGA-coated gold particles. After dehydration and critical point drying, the specimen filters were mounted on copper stubs and coated with carbon. The cells were examined on a JEOL TEMSCAN 100CX II electron microscope. The gold particles could be identified with the EDS analyzer, which was able to detect the Au spectrum when the electron beam was focused on single gold particles using a magnification of 100,000 or more. High-resolution photographs of the same cells were obtained up to the same magnification of 100,000.

Cell Line↗