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PubMed1989

Effects of amphotericin B on the excretory function and the colloid clearance capacity of the perfused rat liver.

The effects of amphotericin B (AmB) on the hepatic excretory function and the colloid clearance capacity were investigated in the perfused rat liver. AmB at 5 or 10 microM caused dose-dependent reductions in bile and perfusate flow rates and in biliary bile acid (BA) excretion. BA concentration in bile tended to increase, due to a prominent reduction in bile water induced by the drug. At 5 microM, AmB also caused an increase in [14C]sucrose clearance by the liver and a release of hepatocytic enzymes into the perfusate. These alterations were not related to the decrease in the perfusate flow induced by AmB. In addition, the drug, at 5 microM, caused a significant decrease in the colloidal carbon clearance by the liver. In this case also, the effect was independent of the reduction in the perfusate flow induced by the drug. The toxic effects of AmB on the rat liver could be interpreted as a derangement of the cell membrane functional integrity, which causes cholestasis, enzyme leakage and an impairment of the reticuloendothelial system function. This latter effect deserves careful evaluation of its clinical implications.

Amphotericin B↗
PubMed1982

Effects of haemorrhage on colloid osmotic pressure in the pigeon.

1. Colloid osmotic pressure, plasma osmolality and plasma protein concentration, percentage composition and A/G ratio were measured before and after haemorrhage in the pigeon. 2. Colloid osmotic pressure, total protein, albumin and beta-globulin concentrations decreased significantly immediately post-haemorrhage, but were significantly elevated after one week. 3. Osmolality and A/G ratio values were significantly increased post-haemorrhage. 4. The results are discussed in relation to fluid exchange across capillaries.

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↗
PubMed1996

A characterisation of dark-field imaging of colloidal gold labels in a scanning transmission X-ray microscope.

While X-ray microscopes provide images of biological specimens for which the contrast is mainly due to the difference in the absorption of carbon and oxygen when X-rays transmitted through the specimen are detected, signals other than absorption can also be used to form images. Using the Stony Brook scanning transmission X-ray microscope at the National Synchrotron Light Source, high-angle dark-field images have been formed of cells labelled with colloidal gold, with and without silver enhancement. The high density of the colloidal gold particles, or the silver particles seeded by the gold, leads to a large scattering signal, and the fact that the particle diameters are comparable to the width of the microscope point spread function results in good localisation of the label with high contrast. The dark-field images can have a greater signal to noise ratio than bright-field images acquired with the same incident X-ray dose. The theory of dark-and bright-field imaging is reviewed. Theoretical calculations of scattering from gold and silver particles are presented and good agreement is found between these and experimental dark-field images of 30 nm diameter gold particles. The signal to noise ratios of experimental bright-and dark-field images are measured and found to be in agreement with theory. Images are presented of cells labelled by immunolabelling and in situ hybridisation.

Fibroblasts↗
PubMed2006

Label-free detection of biomolecules on microarrays using surface-colloid interaction.

Binding of charged nanoparticles to nonmodified DNA and RNA target molecules on microarrays allows detection of these nucleic acids by locating bound nanoparticles on microarray surface. Two computational models have been developed to study the ionic interaction of colloidal particles and biopolymer molecules on a microarray surface. One model represents a basic approach based on mass action law for simulation charge effects versus the chemical composition of the interacting array surface and nanoparticle. The second model is implementation of the advanced Gouy-Chapman-Stern-Graham model for describing effects on liquid-solid interface. We found that both models predict selective binding of colloidal particles to large target molecules on the surface with no binding to smaller capture molecules. This binding regime is considered to be very beneficial for application of charged nanoparticles for detection of nonmodified DNA and RNA target molecules on microarrays. The theoretical considerations are in qualitative agreement with the experimental results for detecting large target DNA and a 50-base long synthetic oligonucleotide on the amino-modified microarray substrate. The experimental and theoretical results of this study allow further development of the label-free microarray technology demonstrated previously for gene expression analysis that is free of reverse transcription and dye labeling.

Colloids↗
PubMed2006

Intraoperative injection of technetium-99m sulfur colloid is effective in the detection of sentinel lymph nodes in breast cancer.

BACKGROUND: Our objective was to determine if intraoperative injection of technetium-99m-labeled sulfur colloid is as effective as preoperative injection in the detection of sentinel lymph nodes (SLNs). METHODS: Two hundred consecutive patients with breast cancer underwent SLN biopsy examination. Radiocolloid was injected in the preoperative area (group A) or immediately after induction of anesthesia in the operating room (group B). RESULTS: The SLN detection rate was similar for groups A (96%) and B (100%; P = .2). Radioactive SLNs were detected in 95% of patients in group A and in 97% of patients in group B (P = .1). The mean number of SLNs harvested was 1.6 and 2.1 for groups A and B, respectively. There was no significant difference in positive SLNs between groups (P = .11). CONCLUSIONS: Intraoperative injection of sulfur colloid is highly effective in the detection of SLNs, avoiding patient discomfort and surgical schedule delays.

Breast Neoplasms↗
PubMedDate not supplied

Understanding the radiolabelling mechanism of 99mTc-antimony sulphide colloid.

The chemistry of antimony trisulphide colloid (ATC) was examined to elucidate the radiolabelling mechanism with 99mTcO4(-). Ion exchange chromatography and atomic absorption spectrophotometry techniques determined ATC to be resistant to hydrolysis in 0.1M hydrochloric acid (HCl) at 25 degrees C or 100 degrees C (>97% recovery, Sb3+ absent). Hydrogen sulphide gas detected did not participate in the mechanism, where antimony trisulphide and 99mTcO4(-) in HCl/100 degrees C yielded 96% 99mTc-product from a K2S-free formulation (versus 98% when K2S was present). 99mTcO4(-) was reduced >90% by DMSA or dithiothreitol under the same conditions, identifying involvement of thiol groups. Infrared analysis of Re-ATC showed S=O bonds, indicating excess thiol groups at the colloid surface were oxidised at the expense of 99mTcO4(-) reduction.

Antimony↗
PubMed2004

The immobilization of hepatocytes on 24 nm-sized gold colloid for enhanced hepatocytes proliferation.

Bioartificial liver and hepatocyte transplantation is anticipated to supply a temporary metabolic support for candidates of liver transplantation or for patients with fulminant liver failure. An essential restriction of this form is the inability to acquire an enough amount of hepatocytes. Enhancement of the proliferation and differentiated function of hepatocytes is becoming a pursued target. Here, porcine hepatocytes were successfully immobilized on nano-sized gold colloid particles to construct a "hepatocyte/gold colloid" interface at which hepatocytes can be quickly proliferated. The properties of this resulting interface were characterized and confirmed by scanning electron microscopy and atomic force microscopy. The proliferative mechanism of hepatocytes was also discussed. The proliferated hepatocytes could be applied to the clinic based on their excellent functions for the synthesis of protein, glucose and urea as well as lower lactate dehydrogenase release.

Animals↗
PubMed2005

Application of a high-performance liquid chromatography fluorescence detector as a nephelometric turbidity detector following Field-Flow Fractionation to analyse size distributions of environmental colloids.

A new operation mode for HPLC-type fluorescence detectors is presented and evaluated using synthetic and environmental particles in the colloidal size range. By applying identical wavelengths for excitation and emission a nephelometric turbidity or single angle light scattering detector is created which can be easily coupled to flow or sedimentation Field-Flow Fractionation (Flow FFF or Sed FFF) for the analysis of colloidal dispersions. The results are compared with standard UV-vis detection methods. Signals obtained are given as a function of particle size and selected detection wavelength. Conclusions can be drawn which affect the current practice of FFF but also for other techniques as groundwater sampling and laboratory column experiments when turbidity is measured in nephelometric mode and in small sample volumes or at low flow rates.

Chromatography, High Pressure Liquid↗
PubMed2004

The primary electroviscous effect in colloidal suspensions.

Although a well-defined electrokinetic phenomenon, the primary electroviscous effect in dilute colloidal suspensions is still an unsolved problem. Most of the experimental tests of the different theories that we have studied have shown a lack of agreement. We have developed, during the last years, new theoretical approaches obtaining, finally, a much better agreement with the experimental results. The corrections are defined in two lines: first, it is accepted that ions present into the Stern layer, in which the fluid is stagnant, can tangentially move; second, it is accepted that the hydrodynamic interaction between colloidal particles exists although the suspensions are extremely diluted. The remarkable conclusion of our work is that the combination of both corrections should give correct theoretical results.

Aluminum Oxide↗
PubMed2004

Manipulating forces between surfaces: applications in colloid science and biophysics.

It is the forces between the microscopic constituents of materials which to a large extent determine the macroscopic properties. For example, it is the differences in bonding between the carbon atoms which determines the different physical properties of carbon and graphite. The same is true in colloidal systems. In colloidal systems, there are three common types of long-range interactions between particles: van der Waals forces, electrical double layer forces and steric forces. In this paper, examples as to how these forces can be modified and even manipulated will be given. To convincingly demonstrate these effects, it is necessary to measure these interaction forces. We have achieved this by using the principles of atomic force microscopy (AFM). The principle is simple, a small particle, 5-30 microm, is attached onto a small weak cantilever spring. The interaction between this particle and another particle or a surface is measured by monitoring the deflection of the spring as the two particles are moved together. In this paper, I shall give examples of direct measurements of van der Waals, electrical double layer and steric forces and show how they can be modified and how these modifications affect the properties of bulk suspensions. Similar principles are involved in the interactions of biological materials. However, nature is much cleverer than man such that many of the macromolecules on cell surfaces are able to specifically recognise only one other molecule. An example of this recognition-type interaction, namely, cholera toxin interacting with the glycolipid Gm1, will also be presented. Finally, the adhesion of cells to surfaces of different surface chemistries has been determined; this is of significance in many fields ranging from fouling of filtration membranes on the one hand to the biocompatibility of surgical implants on the other.

Adsorption↗
PubMed2005

Monte Carlo simulation of colloidal membrane filtration: principal issues for modeling.

The principal issues involved in developing a Monte Carlo simulation model of colloidal membrane filtration are investigated in this study. An important object for modeling is the physical dynamics responsible for causing particle deposition and accumulation when encountering an open system with continuous outflow. A periodic boundary condition offers a solution to the problem by recirculating continuous flow back through the system. Scaling to full physical dimensions will allow for release of the model from flawed assumptions such as constant cake layer volume fraction and thickness throughout the system. Furthermore, rigorous modeling on a precise scale extends the model to account for random particle collisions with acute accuracy. A major finding of this study proves that forces within the colloidal filtration system are summed and transferred cumulatively through the inter-particle interactions. The force summation and transfer phenomenon only realizes its true value when the model is scaled to full dimensions. The overall strategy for model development, therefore, entails three stages: first, rigorous modeling on a microscopic scale; next, comprehensive inclusion of relevant physical dynamics; and finally, scaling to full physical dimensions.

Colloids↗
PubMed2005

Preparation of gold colloid monolayer by immunological identification.

The design and initial characterization of the self-assembled gold colloid monolayer by a sandwich structure via the immunological identification are reported. The 13 nm gold colloid nanoparticles and the silicon or quartz substrates have been modified with the mouse polyclonal antibody against hepatitis B virus surface antigen (PAb) and the mouse monoclonal antibody against hepatitis B virus surface antigen (MAb), respectively. They can be linked by a special reaction with their corresponding hepatitis B virus surface antigen (Antigen) as a sandwich structure. Thus, the density of gold nanoparticles self-assembled on the substrate can be readily controlled by the amount of the antigen added. The resulting substrates have been characterized by atomic force microscopy (AFM) and surface-enhanced Raman scattering (SERS) spectroscopy when the gold nanoparticles were modified with SERS-active probe molecules of 4-mercaptobenzoic acid (MBA) after silver enhancement. These data show that the gold nanoparticles are separately fixed onto the substrate and form a uniform monolayer, which possess a set of features that make them very attractive for both basic and applied uses, including roughness, high stability, and biocompatibility.

Animals↗
PubMed2005

Colloidal stability of aqueous polymeric dispersions: effect of pH and salt concentration.

Aqueous film coatings often contain some electrolytes, organic acids, and pigments to give functions of sustained release, time-controlled release, or protection against light. Additions of some electrolytes or organic acids into latex dispersion for an aqueous film coating affect its colloidal stability. We characterized the aqueous polymeric latexes used in the pharmaceutical industry by measuring zeta potential and particle size, and evaluated this colloidal stability using DLVO theory. Three polymethacrylate-based aqueous polymeric latexes, Eudragit L30D-55, Eudragit RS30D and Eudragit NE30D, having anionic, cationic, and neutral polymer, respectively, were used in this study. The Hamaker constant of the polymethacrylate-based latex was determined to be 6.35 x 10(-21) J, and the total potential energy of the latex dispersion was calculated. The total potential energy of interaction between pairs of latex particles changes by altering the salt concentration and pH. The experimental results of stability in the anionic and the cationic latex dispersions can be explained by the total interaction energies. However, the stabilization of the neutral latex did not match the calculated result. The steric interaction produced by the surfactant likely resulted in the stable dispersion of this latex.

Algorithms↗
PubMed2006

Effects of low-molecular-weight organic ligands and phosphate on DNA adsorption by soil colloids and minerals.

Adsorption of DNA on montmorillonite, kaolinite, goethite and soil clays from an Alfisol in the presence of citrate, tartrate and phosphate was studied. A marked decrease in DNA adsorption was observed on montmorillonite and kaolinite with increasing anion concentrations from 0 to 5 mM. However, the amount of DNA adsorbed by montmorillonite and kaolinite was enhanced when ligand concentration was higher than 5 mM. In the system of soil colloids and goethite, with the increase of anion concentrations, a steady decrease was found and the ability of ligands in depressing DNA adsorption followed the sequence: phosphate > citrate > tartrate. Compared to H2O2-treated clays (inorganic clays), a sharp decrease in DNA adsorption was observed on goethite and organo-mineral complexes (organic clays) with increasing ligand concentrations. The results suggest that the influence of anions on DNA adsorption varies with the type and concentration of anion as well as the surface properties of soil components. Introduction of DNA into the system before the addition of ligands had the greatest amount of DNA adsorption on soil colloids and goethite. Organic and inorganic ligands promoted DNA adsorption on montmorillonite and kaolinite when ligands were introduced into the system before the addition of DNA. The results obtained in this study have important implications for the understanding of the persistence and fate of DNA in soil environments especially rhizosphere soil where various organic and inorganic ligands are active.

Adsorption↗
PubMed2006

Drying dissipative patterns of the colloidal crystals of silica spheres in an dc-electric field.

Drying dissipative structural patterns of the colloidal crystals of silica spheres were studied under an dc-electric field. Platinum plate electrodes of anode and cathode were set on a cover glass. The broad hills accumulated with the spheres were observed at the outer edges of the dried film without and also with the electric fields. The column-like structures were formed by the electric flux, and movement of the spheres took place toward anode. The dried film kept colloidal crystal structure, where the nearest-neighbored spheres contact each other more compactly in the areas closer to the anode. Drying times needed for the complete dryness of the suspensions decreased as the strength of the electric field increased. Addition of sodium chloride to the suspensions retarded the movement of spheres toward the anode substantially.

Colloids↗
PubMed2006

Dynamics of ultrasonically induced birefringence of in rod-like colloidal solutions.

This review summarized our experimental studies of ultrasonically induced birefringence on aqueous solution of rigid rod-like colloids and rod-like micelles from the view point of dynamics of particle orientation. For rigid rod-like colloids in dilute concentration, the orientational relaxation time was described in terms of the Debye-Einstein equation. This indicated that the ultrasonically induced birefringence could be one of useful tools for determining the size of particles of anisotropic shape. For rod-like micelles, the birefringence showed anomalous damping oscillation when the rod-like micelle was in an entangling state. The mechanism of damping oscillation was discussed using the results of the rheological measurements.

Birefringence↗
PubMed2006

Electrophoretic flow behaviour and mobility of colloidal fluids and crystals.

We report on measurements of the electrophoretic mobility mu of charged colloidal spheres in the deionized state, where the suspensions show fluid or crystalline order. In the fluid state, parabolic flow profiles are observed due to electro-osmotic solvent flow. In the crystalline state, complex flow profiles occur due to additional crystal cohesion. The mobility mu then may inferred from the flow velocity averaged over the complete cell cross section as performed in our home built super-heterodyne Doppler velocimeter. For two particle species of 68 and 122 nm diameter we measured mu as a function of particle concentration. Starting from a plateau value at low concentration, mu decreases approximately logarithmically with increased concentration. Interestingly, the decrease of mu is not affected by the phase transition, indicating that electro-kinetic properties may be viewed as single particle properties even in the case of structure formation. Moving further along this line of thought, we show that this behaviour may indeed be captured near quantitatively by an ad hoc combination of charge renormalization calculations and the Standard Electro-kinetic Model originally designed for isolated, non-interacting particles. From this coincidence, we may conclude that (i) counter-ion condensation behind the hydrodynamic slip plane is the dominant effect of finite particle concentrations and leads to a decrease of the effective particle charge and (ii) an increased colloid concentration can be understood in terms of an elevated total ion concentration and that (iii) it can thus be reduced to a modification of the screening parameter, such that the problem can be mapped onto a single particle theory for an infinite electrolyte.

Acrylates↗