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At least 163 records · Page 9Linked to original sources
PubMed1991

Light microscopic localization of silver-enhanced liposome-entrapped colloidal gold in mouse tissues.

Silver-enhanced liposome-entrapped colloidal gold was developed for light microscopic localization of liposomes. Preparation of colloidal gold entrapped in liposomes was achieved by a modified method of Hong, et al. (1983) Biochim. Biophys. Acta 732, 320-323). In this report, a gold chloride/citrate solution of low pH (3.4) was used to inhibit the formation of gold granules during the liposome preparation. The diameter of most liposomes ranged from 80 to 100 nm. Following liposome preparation, the pH was adjusted to 6, and the temperature increased to 55 degrees C. The majority of the liposomes contained one to three gold particles. Liposomes were injected into mice via tail vein; 24 h later, tissues were collected. Sections were processed for silver enhancement of the gold particles and examined by light microscopy. Silver-enhanced gold particles were clearly observed in both liver and implanted tumor. Localization was confirmed by electron and fluorescence microscopy. Thus, we have shown that silver enhancement of colloidal gold liposomes is a direct and sensitive method for tracing the fate of liposomes in vivo, providing minimal background interference and a good definition of various cell types.

Animals↗
PubMed1988

Preparation of colloidal gold for staining proteins electrotransferred onto nitrocellulose membranes.

This paper describes a simple method of preparing colloidal gold for staining protein blots. Colloidal gold was prepared from 0.005 or 0.01% HAuCl4 by the addition of formalin as a reductant and potassium hydroxide. Staining of small cell carcinoma tissue extract blotted onto nitrocellulose membranes with this colloidal gold solution resulted in the appearance of a large number of clear wine-red bands. The sensitivity of gold staining was 60 times higher than that of Coomassie brilliant blue staining and almost comparable to that of silver staining of proteins in polyacrylamide gel. The sensitivity of this method was also satisfactory in comparison with that of enzyme immunoblotting. The colloidal gold prepared by this method is usable for routine work.

Blotting, Western↗
PubMed1992

Colloidal gold uptake as a marker for monocyte differentiation and maturation in normal and leukemic cells.

The uptake of colloidal gold particles by human monocytes was studied by electron microscopy, with special emphasis on changes in this uptake during the differentiation and maturation of these cells. The way in which leukemic cells of childhood acute non-lymphocytic leukemia (ANLL) can function in this gold uptake was also examined. In monocytes, microendocytosis was temperature-dependent; colloidal gold uptake increased as temperatures rose from 4 degrees C to 37 degrees C. It appeared that gold particles first adhered to the cell surface membrane, were then incorporated into the cytoplasmic vesicles, and then were transported into the granules. Original HL-60 cells and retinoic acid (RA)-treated HL-60 cells, which were differentiating and maturing along the granulocyte lineage, did not ingest colloidal gold particles, but 1,25(OH)2D3-treated HL-60 cells showed colloidal gold uptake during their differentiation and maturation along the monocyte lineage: 68.6% of the cells contained gold particles. Gold uptake was demonstrated in 27.3% of original U937 cells; the percentage increased to 70.3% when they were induced to mature by RA. In 15 specimens of childhood ANLL, none of the M1, M2 or M3 cells showed colloidal gold uptake, whereas 76-97% of M4 and M5 cells showed this uptake. These findings indicate that colloidal gold uptake is a marker of monocyte differentiation and maturation and can provide additional information for ANLL cytology.

Adolescent↗
PubMed1986

Silver-enhanced colloidal gold as a cell surface marker for photoelectron microscopy.

Colloidal gold labeling in conjunction with silver enhancement was investigated as a labeling technique for photoelectron microscopy (PEM). PEM uses UV-stimulated electron emission to image uncoated cell surfaces, and markers for cell surfaces need to be sufficiently photoemissive to be clearly visible against this background. Label contrast provided by 6 nm or 20 nm colloidal gold markers alone was compared to that provided by 6 nm markers after silver enhancement, using both direct and indirect labeling methods for fibronectin on human fibroblast cell surfaces. In all cases, details of the fibrillar fibronectin labeling distribution which were barely discernible before silver enhancement became highly visible against the cellular surface features. Two factors evidently contribute to the pronounced increase in label contrast with silver enhancement: (1) Increased particle size, which was documented by transmission electron microscopy, and (2) increased photoemission resulting from a silver coating on the enhanced gold markers, compared with the protein coating on the unenhanced gold markers. These data demonstrate that silver enhancement of colloidal gold labeling patterns in PEM images is a highly effective method for localization of specific sites on cell surfaces.

Cell Membrane↗
PubMed1994

A general method for plasma membrane isolation by colloidal gold density shift.

A general method for isolating plasma membranes is described. Vegetative amoebae of Dictyostelium discoideum were allowed to directly adsorb raw colloidal gold of particle diameter 10-20 nm. After quenching the gold surface, the cells were lysed and the lysates were diluted in 60% sucrose and centrifuged through a 65% sucrose cushion to selectively pellet the gold-laden membranes. Three generally applicable exogenous cell surface markers were used to follow the plasma membranes: intercalated [3H]cholesterol, octadecylrhodamine, and the adsorbed gold colloid itself. The isolates routinely contained approximately 60% of these tags, enriched approximately 15-fold with respect to protein. The recovery and degree of enrichment of contaminating markers in the plasma membrane fraction were lysosomes (3% and 1-fold); mitochondria (11% and 3-fold); rough endoplasmic reticulum, as reflected by RNA (3% and 0.7-fold); and DNA (9% and 4-fold). Membrane proteins and lipids were quantitatively solubilized from the gold by detergents. We conclude that this methodology provides an approach to the isolation of plasma membranes which compares favorably to existing techniques with respect to yield, purity, and ease.

Cell Membrane↗
PubMed2005

Surface-enhanced Raman spectroscopy substrate composed of chemically modified gold colloid particles immobilized on magnetic microparticles.

In this paper, immobilization of gold colloidal particles onto amine-modified magnetic microparticles is demonstrated. Once immobilized, the gold was then reacted with pentachlorothiophenol (PCTP) to form a self-assembled monolayer. The PCTP-gold colloid on magnetic microparticles was then used to extract naphthalene from aqueous samples. A magnet was used to concentrate the microparticles onto the side of the sample vial, allowing detection of naphthalene by surface-enhanced Raman spectroscopy. Using the PCTP-gold colloid on magnetic microparticles the limit of detection for naphthalene achieved was 0.3 microg mL(-1). Multiple extractions can be done with the PCTP-gold colloid on magnetic microparticles to further lower the detection limit.

Journal Article↗
PubMedDate not supplied

Colloidal gold: a novel nanoparticle vector for tumor directed drug delivery.

Colloidal gold, a sol comprised of nanoparticles of Au(0), has been used as a therapeutic for the treatment of cancer as well as an indicator for immunodiagnostics. However, the use of these gold nanoparticles for in vivo drug delivery has never been described. This communication outlines the development of a colloidal gold (cAu) nanoparticle vector that targets the delivery of tumor necrosis factor (TNF) to a solid tumor growing in mice. The optimal vector, designated PT-cAu-TNF, consists of molecules of thiol-derivatized PEG (PT) and recombinant human TNF that are directly bound onto the surface of the gold nanoparticles. Following intravenous administration, PT-cAu-TNF rapidly accumulates in MC-38 colon carcinoma tumors and shows little to no accumulation in the livers, spleens (i.e., the RES) or other healthy organs of the animals. The tumor accumulation was evidenced by a marked change in the color of the tumor as it acquired the bright red/purple color of the colloidal gold sol and was coincident with the active and tumor-specific sequestration of TNF. Finally, PT-cAu-TNF was less toxic and more effective in reducing tumor burden than native TNF since maximal antitumor responses were achieved at lower doses of drug.

Animals↗
PubMed2003

[Study on the clinical use of alpha-fetoprotein (AFP) colloidal gold diagnostic strip].

OBJECTIVE: To test the sensitivity and specificity of alpha-fetoprotein (AFP) colloidal gold diagnostic strip as compared with RIA-AFP diagnostic kit. METHODS: Double blind method was used to test sera from 426 healthy people and 1567 patients selected in two general hospitals and a cancer hospital. Each serum was measured by RIA-AFP and AFP colloidal gold diagnostic strip on the same day. RIA-AFP diagnostic results was identified as true positive or negative. RESULTS: Among 426 healthy people, all the RIA-AFP test showed negative result (serum AFP concentration less than 25 IU/ml), but the AFP colloidal gold diagnostic strip had 1.88% false positive. When comparing the result from 1567 patients measured by RIA-AFP, the sensitivity and specificity of AFP colloidal gold diagnostic strip were 99.3%, and 97.2%, respectively. The crude correspondence rate between the two diagnostic regents was 97.6%. CONCLUSION: AFP colloidal gold diagnostic strip showed very good result and could be used as a screening diagnostic kit in clinic and hospital settings.

Biomarkers, Tumor↗
PubMed1999

Colloidal gold filtrates as metal substrates for surface-enhanced infrared absorption spectroscopy.

A new method for obtaining surface-enhanced infrared absorption (SEIRA) spectra of antibodies and antibody/antigen complexes has been developed. Antibodies attached to colloidal gold particles and then collected by filtration onto porous polyethylene membranes show enhanced spectral bands at 1080 and 990 cm-1 regardless of the antibody specificity. Attachment of a model antigen, glucose oxidase, to its specific antibody/colloid complex prior to collection produces enhanced bands at 1540, 1395, and 1250 cm-1. Similarly, when the antigen Salmonella is attached to its specific antibody/colloid complex prior to collection, a new enhanced band is observed at 1015 cm-1. Similarities and differences of the SEIRA spectra obtained on gold colloid are compared to previous work on gold films.

Antibodies↗
PubMedDate not supplied

[Effect of colloid gold on physiologic-biochemical processes in Escherichia coli 1257].

The influence of colloid gold on the growth processes, ATP-ase activity and extrusion of protons in Escherichia coli 1257 was studied. The particles of colloid gold exert nonmonotonous influence on these processes with different direction is such a way that small concentration of this metal (5 x 10(-7)-5 x 10(-6) mg/ml) exert stimulative effect, while higher concentrations of colloid gold result in the suppression of biological activity of the bacterial cells. The discovered peculiarities of colloid gold influence of E. coli strain may be determined by specificity of contact interaction of metal particles with the surface of bacterial cells.

Adenosine Triphosphatases↗