scholarly journals Thiol-mediated degradation of DNA adsorbed on a colloidal gold surface

2003 ◽  
Vol 78 (4) ◽  
pp. 471-473 ◽  
Author(s):  
Shalu Mittal ◽  
Frederic Bushman ◽  
Leslie E Orgel
Keyword(s):  
Colloidal Gold ◽  
Gold Surface

Part III: Surface-Enhanced Raman Scattering of Amino Acids and Their Homodipeptide Monolayers Deposited onto Colloidal Gold Surface

2005 ◽  
Vol 59 (12) ◽  
pp. 1516-1526 ◽  
Author(s):  
Edyta Podstawka ◽  
Yukihiro Ozaki ◽  
Leonard M. Proniewicz
Keyword(s):  
Amino Acids ◽  
Raman Scattering ◽  
Colloidal Gold ◽  
Gold Surface ◽  
Surface Enhanced Raman Scattering ◽  
Competitive Interactions ◽  
Surface Geometry ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

Surface-enhanced Raman scattering (SERS) spectra were measured for monolayers of various amino acids: L-methionine (Met), L-cysteine (Cys), L-glycine (Gly), L-leucine (Leu), L-phenylalanine (Phe), and L-proline (Pro) and their homodipeptides (Met-Met, Cys-Cys, Gly-Gly, Leu-Leu, Phe-Phe, and Pro-Pro) deposited onto a colloidal gold surface. Orientation of amino acids and their homodipeptides, as well as specific-competitive interactions of their functional groups with the gold surface, were predicted by detailed spectral analysis of the obtained SERS spectra. The analysis performed allowed us to propose a particular surface geometry for each amino acid and homodipeptide on the gold surface. In addition, we compared the structures of these molecules adsorbed on colloidal gold and silver surfaces.

Immunolabeling efficiency of protein A-gold complexes.

1990 ◽  
Vol 38 (11) ◽  
pp. 1523-1530 ◽  
Author(s):  
L Ghitescu ◽  
M Bendayan
Keyword(s):  
Colloidal Gold ◽  
Colloidal Particle ◽  
Protein A ◽  
Particle Diameter ◽  
Gold Surface ◽  
Scatchard Analysis ◽  
Particle Sizes ◽  
Adsorption Parameters ◽  
High Affinity ◽  
Low Concentrations

A systematic study of the adsorption of protein A on colloidal gold particles varying in size from 5-16 nm was performed at different protein concentrations. The number of protein A molecules bound per colloidal particle was evaluated and the Scatchard analysis of the adsorption parameters was applied for each size of the colloid. The binding of protein A to the colloidal gold surface exhibited the same affinity pattern for all of the particle sizes. At low concentrations of stabilizing protein, adsorption took place with high affinity (Kd 1.96-3.3 nM) and the maximum number of protein A molecules attached with this affinity correlated well with the surface of the particle. At higher concentrations of protein A, adsorption exhibited a significantly lower affinity (Kd 530-800 nM), and no saturation was recorded. Competition by albumin did not reveal a preferential removal of the "low-affinity" bound protein A molecules, contradicting the model of successive shells of stabilizing protein around the colloidal particle. The immunolabeling efficiency of conjugates having the same size of gold nucleus but carrying different numbers of protein A molecules was comparatively investigated by quantitative post-embedding immunocytochemistry. Protein A-gold formed with 5-10-nm colloids gave the highest intensity of labeling when carrying the maximum number of protein A molecules that could be adsorbed with high affinity. Overloading as well as underloading these complexes resulted in a significant decrease of their immunoreactivity. The most efficient conjugates were obtained when stabilization was performed with 6 micrograms protein A/ml gold sol of 5 and 10 nm particle diameter, and 15 micrograms protein/ml of 15-nm colloid.

Backscattered-electron imaging of the colloidal gold surface marker

1984 ◽  
Vol 42 ◽  
pp. 254-255
Author(s):  
E. de Harven ◽  
R. Leung ◽  
H. Christensen
Keyword(s):  
Colloidal Gold ◽  
High Efficiency ◽  
Human Peripheral Blood ◽  
Gold Surface ◽  
Blood Leukocytes ◽  
Backscattered Electron Imaging ◽  
Carbon Coated ◽  
Backscattered Electron ◽  
Electron Imaging ◽  
Gold Marker

A variety of markers have been used for surface labeling with the scanning electron microscope (1). They are all recognized in the secondary electron imaging (SEI) mode on the basis of their characteristic sizes and shapes. This makes it difficult, however, to recognize unambiguously markers of small size (smaller than 40 nm). Unfortunately, markers of such size are needed if one wishes to minimize steric hindrance phenomena (2) and therefore obtain high efficiency labeling. We have found that the atomic number contrast of the colloidal gold marker, expressed in the backscattered electron imaging (BEI) mode, alleviates this difficulty to a significant extent (3).Human peripheral blood leukocytes, separated by sedimentation in presence of Dextran, were attached to poly-1-lysine pretreated carbon coated grids. The cells were then fixed for 5 min with 0.25% solution of buffered glutaraldehyde, pH 7.2, extensively rinsed with 0.1% glycine in PBS, and incubated for 30 min, at room temperature with an IgM monoclonal antibody (D2) specifically recognizing, a surface antigen of mature granulocytes.

Origin of Laser-Induced Colloidal Gold Surface Oxidation and Charge Density, and Its Role in Oxidation Catalysis

2020 ◽  
Vol 124 (38) ◽  
pp. 20981-20990 ◽  
Author(s):  
Anna R. Ziefuß ◽  
Ina Haxhiaj ◽  
Stefan Müller ◽  
Mustafa Gharib ◽  
Olga Gridina ◽  
...  
Keyword(s):  
Charge Density ◽  
Colloidal Gold ◽  
Surface Oxidation ◽  
Gold Surface ◽  
Oxidation Catalysis

3-D organization of fibrinogen receptors using computer reconstruction and whole-mount microscopy

1988 ◽  
Vol 46 ◽  
pp. 30-31
Author(s):  
E. T. O'Toole ◽  
R. R. Hantgan ◽  
J. C. Lewis
Keyword(s):  
Whole Blood ◽  
Colloidal Gold ◽  
Blood Platelets ◽  
Cell Contact ◽  
Computer Assisted ◽  
Adherent Cells ◽  
Differential Centrifugation ◽  
Computer Reconstruction ◽  
Sds Page ◽  
Whole Mount

Thrombocytes (TC), the avian equivalent of blood platelets, support hemostasis by aggregating at sites of injury. Studies in our lab suggested that fibrinogen (fib) is a requisite cofactor for TC aggregation but operates by an undefined mechanism. To study the interaction of fib with TC and to identify fib receptors on cells, fib was purified from pigeon plasma, conjugated to colloidal gold and used both to facilitate aggregation and as a receptor probe. Described is the application of computer assisted reconstruction and stereo whole mount microscopy to visualize the 3-D organization of fib receptors at sites of cell contact in TC aggregates and on adherent cells.Pigeon TC were obtained from citrated whole blood by differential centrifugation, washed with Ca++ free Hank's balanced salts containing 0.3% EDTA (pH 6.5) and resuspended in Ca++ free Hank's. Pigeon fib was isolated by precipitation with PEG-1000 and the purity assessed by SDS-PAGE. Fib was conjugated to 25nm colloidal gold by vortexing and the conjugates used as the ligand to identify fib receptors.

The Application of Protein A-Gold Immunocytochemistry to Studies of Protein Secretion

1985 ◽  
Vol 43 ◽  
pp. 426-429
Author(s):  
George H. Herbener ◽  
Antonio Nanci ◽  
Moise Bendayan
Keyword(s):  
Tissue Section ◽  
Colloidal Gold ◽  
Unit Area ◽  
Protein A ◽  
Extracellular Proteins ◽  
Gold Complex ◽  
Second Step ◽  
Igg Antibodies ◽  
Tissue Sections ◽  
Antigenic Sites

Protein A-gold immunocytochemistry is a two-step, post-embedding labeling procedure which may be applied to tissue sections to localize intra- and extracellular proteins. The key requisite for immunocytochemistry is the availability of the appropriate antibody to react in an immune response with the antigenic sites on the protein of interest. During the second step, protein A-gold complex is reacted with the antibody. This is a non- specific reaction in that protein A will combine with most IgG antibodies. The ‘label’ visualized in the electron microscope is colloidal gold. Since labeling is restricted to the surface of the tissue section and since colloidal gold is particulate, labeling density, i.e., the number of gold particles per unit area of tissue section, may be quantitated with ease and accuracy.

Comparative strengths and weaknesses of peroxidase and colloidal gold in pre- and post-embedding immunolabeling techniques

1987 ◽  
Vol 45 ◽  
pp. 1002-1005
Author(s):  
D. R. Abrahamson ◽  
P. L. St.John ◽  
E. W. Perry
Keyword(s):  
Electron Microscopy ◽  
Horseradish Peroxidase ◽  
Light Microscopy ◽  
Colloidal Gold ◽  
Light Microscope ◽  
Ultrastructural Localization ◽  
The Other ◽  
Quantitative Studies ◽  
Dense Suspension ◽  
Antigen Localization

Antibodies coupled to tracers for electron microscopy have been instrumental in the ultrastructural localization of antigens within cells and tissues. Among the most popular tracers are horseradish peroxidase (HRP), an enzyme that yields an osmiophilic reaction product, and colloidal gold, an electron dense suspension of particles. Some advantages of IgG-HRP conjugates are that they are readily synthesized, relatively small, and the immunolabeling obtained in a given experiment can be evaluated in the light microscope. In contrast, colloidal gold conjugates are available in different size ranges and multiple labeling as well as quantitative studies can therefore be undertaken through particle counting. On the other hand, gold conjugates are generally larger than those of HRP but usually can not be visualized with light microscopy. Concern has been raised, however, that HRP reaction product, which is exquisitely sensitive when generated properly, may in some cases distribute to sites distant from the original binding of the conjugate and therefore result in spurious antigen localization.

Intralysosomal Accumulation of Colloidal Gold-Low Density Lipoprotein Conjugates in Chloroquine-Treated Fibroblasts

1985 ◽  
Vol 43 ◽  
pp. 546-547 ◽  
Author(s):  
Dean A. Handley ◽  
Cynthia M. Arbeeny ◽  
Larry D. Witte
Keyword(s):  
Colloidal Gold ◽  
Cultured Cells ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Coated Vesicle ◽  
Low Density ◽  
Cholesterol Esters ◽  
Cultured Fibroblasts ◽  
Surface Receptors ◽  
Ldl Particles

Low density lipoproteins (LDL) are the major cholesterol carrying particles in the blood. Using cultured cells, it has been shown that LDL particles interact with specific surface receptors and are internalized via a coated pit-coated vesicle pathway for lysosomal catabolism. This (Pathway has been visualized using LDL labeled to ferritin or colloidal gold. It is now recognized that certain lysomotropic agents, such as chloroquine, inhibit lysosomal enzymes that degrade protein and cholesterol esters. By interrupting cholesterol ester hydrolysis, chloroquine treatment results in lysosomal accumulation of cholesterol esters from internalized LDL. Using LDL conjugated to colloidal gold, we have examined the ultrastructural effects of chloroquine on lipoprotein uptake by normal cultured fibroblasts.

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