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PubMed1988

The use of colloidal gold immunoelectron microscopy to diagnose varicella-zoster virus (VZV) infections by rapid discrimination between VZV, HSV-1 and HSV-2.

Colloidal gold immunoelectron microscopy was used to diagnose rapidly 53 cases clinically suspected of varicella-zoster virus (VZV) infection and one special case selected from another study on typical herpes simplex virus (HSV) infections. The viruses were identified and subsequently typed within 2.5 h by a direct labelling test for VZV, and within 3.5 h by an indirect labelling test with monoclonal antibodies against HSV type 1 and type 2. The protein A purified IgG fraction of human anti-VZV immunoglobulins was adsorbed to colloidal gold particles, and the specificity of the gold-labelled antibodies was tested with several human and animal herpesviruses. Viral envelopes did not crossreact in the direct labelling test. However, an indirect labelling procedure revealed that a small fraction of the anti-VZV antibodies crossreacted with the cores of herpes simplex virus and pseudorabies virus (Aujeszky disease virus). Virus-infected cellular material taken from typical herpetic lesions was used directly without virus propagation for virus typing. All cases (N = 54) were analyzed without knowing the clinical description of the results of cytopathologic examination (Tzanck smear) and viral culture. Forty-four cases were identified as VZV; however, 5 of the supposed VZV infections were proved to be HSV infections. Although the viral culture of the one HSV case was HSV- and VZV-negative, colloidal gold labelling identified the case as VZV infection. In 16 cases virus immunoglobulin complexes were detected by using gold-tagged antibodies against human immunoglobulins. Immunoglobulins on the viral envelopes did not interfere with virus typing by immunogold labelling.

Antibodies, Viral↗
PubMed1978

Change of the protein composition of the thyroid colloid during treatment with propylthiouracil and thyroxine: a microgel electrophoretic study of single rat thyroid follicles.

Prophylthiouracil and thyroxine were given daily to rats for 4 weeks. Samples of colloid were collected in vivo from the superficial thyroid follicles during this period and their protein composition was analysed by gel electrophoresis. It was observed that the aggregates of thyroglobulin, i.e., the 27-S thyroid iodoprotein and the heavier fractions, were reduced to 50% after 1 week and were almost absent after 2 weeks. A faster migrating thyroglobulin fraction was observed in the samples of colloid and in the homogenate of the whole gland after 48 h of treatment. During the following period of treatment there was an increase in the relative amount of the faster migrating thyroglobulin fraction compared to 19-S thyroglobulin in the colloid, the former comprising approx. 75% of the globulins after 4 weeks, It can be concluded that propylthiouracil inhibits the formation of the 27-S iodoprotein and that a structurally altered and iodine-poor thyroglobulin fraction is accumulated in the follicle lumen.

Animals↗
PubMedDate not supplied

Clinical-computed tomographic correlations in colloid cysts of the third ventricle.

The clinical and CT findings in 12 patients with colloid cysts are described. Eleven lesions appeared hyperdense on the plain scan and only one lesion was isodense. Five of the lesions showed contrast enhancement. Ten of twelve lesions had associated hydrocephalus. Two patients with colloid cyst had no abnormal neurological findings on examination; and it is unlikely that the symptoms which led to the performance of the CT scan were related to the colloid cyst.

Adult↗
PubMed1991

High precision immunoscanning electron microscopy using Fab fragments coupled to ultra-small colloidal gold.

Ultra-small colloidal gold (less than 1 nm), bound to Fab fragments provides the shortest practical specific marker system to date and can be used in concert with field emission scanning electron microscopes to precisely locate antigenic sites. An "in-lens" FE-SEM equipped with a highly sensitive single crystal YAG-detector for backscattered electrons, as well as the use of advanced specimen preparation techniques based on cryofixation, are among the indispensible prerequisites. A T-even type Escherichia coli bacteriophage, Tu II*-46, was chosen to study properties of the immunogold labeling system. Distinct regions on the tail fibers of this phage were labeled with Fab fragments derived from antibodies against the related phage Tu II*-6. The tail fibers are composed of pairs of homologous proteins, thus offering two identical antigenic sites at the same locus on the tail fibers. Fab fragments can be visualized in the SEM at high accelerating voltage (30 kV) without any additional marker. This permits comparison of the labeling characteristics of unmarked and colloidal gold-marked Fab fragments. Unmarked Fab fragments often bind by pairs (two singlet Fab fragments bound opposed to each other along the axis of the tail fiber). The labeling efficiency of unmarked Fab fragments was greater than that of ultra-small gold-labeled Fab fragments. Binding by pairs was not seen after labeling with ultra-small gold-Fab fragments. The conjugates used in this study exhibited one colloidal gold per Fab fragment.

Animals↗
PubMed1991

Priming solutions for cardiopulmonary bypass: comparison of three colloids.

The present study was designed to compare the differences in the clinical effects of three colloidal solutions, albumin, urea-linked gelatin, and succinyl-linked gelatin, when used as priming fluids for cardiopulmonary bypass (CPB) under alpha-stat conditions. A consecutive series of 105 patients scheduled for cardiac surgery were randomized into three identically managed groups, except for the CPB prime. Variables relating to acid-base status, oncotic activity, metabolism, coagulation, and postoperative evaluation were measured. Marked differences in acid-base status, colloid osmotic pressure, additional prime requirements, blood lactate, urine output, and the need for buffer solutions occurred among groups, with the succinyl-linked gelatin group having better results than the other groups. Changes in hemodynamics, oxygen consumption, and blood-glucose levels during CPB did not vary among groups. There were also no important intergroup differences in hematologic and clotting variables or postoperative parameters such as blood loss or use of blood products. Electrolyte changes were similar except for a significant increase in ionized calcium that occurred in the urea-linked gelatin group after bypass. The results indicate that succinyl-linked gelatin is an adequate and safe alternative to human albumin for use as a colloid during CPB under alpha-stat conditions.

Acid-Base Equilibrium↗
PubMed2005

Increasing age does not affect efficacy of sentinel lymph node biopsy using smaller-sized technetium-99m tin colloids for breast cancer patients.

BACKGROUND: Increasing age of breast cancer patients was reported to cause not only failure of sentinel lymph node (SLN) identification but also false negative results. METHODS: A retrospective review was conducted of breast cancer patients who underwent sentinel lymph node biopsy (SLNB) using small-sized technetium-99m-labeled tin colloid (particle size: 200-400 nm in diameter). A comparison between 82 patients who were less than 60 years and 40 patients who were > or =60 years of age was performed to evaluate the efficacy of SLNB using the small-sized tin colloid in older patients. RESULTS: One hundred twenty-two clinically node-negative breast cancer patients underwent SLNB. Apart from age, there were no statistically significant differences between the younger patients and the older patients in terms of the clinicopathologic characteristics. Successful mapping rates, false negative rates, and accuracy were comparable between the 2 groups. CONCLUSIONS: SLNB using the small-sized tin colloid was not affected by increasing age.

Adult↗
PubMed2006

Effects of organic ligands, electrostatic and magnetic interactions in formation of colloidal and interfacial inorganic nanostructures.

This paper discusses effects of organic ligands, electrostatic and magnetic interactions involved in morphological control of chemically synthesized inorganic nanostructures including colloid and planar systems. The special attention was concentrated on noble metal (gold and palladium) nanoparticles and nanostructures formed at the gas-liquid interface. The analysis of experimental data showed that electrostatic and ligand-related interactions influence very strongly on the metal nanostructure morphology. The hydrophobicity of ligand, charge and binding affinity to inorganic phase are important factors influencing the morphology of inorganic nanostructures formed in a layer at the gas/liquid interface by the interfacial synthesis method. The important point of this method is the quasi two-dimensional character of reaction area and possibilities to realize ultimately thin and anisotropic dynamic monomolecular reaction system with two-dimensional diffusion and interactions of precursors, intermediates and ligands resulting in planar growth and organization of inorganic nanoparticles and nanostructures in the plain of Langmuir monolayer. The morphology of resulting inorganic nanostructures can be controlled efficiently by variations of growth conditions via changes in state and composition of interfacial planar reaction media with the same precursor, and by variations of composition of adjacent bulk phases. The extreme anisotropy and heterogeneity of two-dimensional interfacial reaction system allows creating conditions when growing inorganic particles floating on the aqueous phase surface interact selectively with hydrophobic water-insoluble ligands in interfacial monolayer or with hydrophilic bulk-phase ligands, or at the same time with ligands of different nature present in monolayer and in aqueous phase. The spatial anisotropy of interfacial reaction system and non-homogeneity of ligand binding to inorganic phase gives possibilities for growth of integrated anisotropic nanostructures with unique morphologies, in particularly those characterized by very high surface/volume ratio, high effective perimeter, and labyrinth-like structure. In a case of magnetic nanoparticles dispersed in colloids specific magnetic dipolar interactions can result in formation of chains, rings and more complex nanoparticulate structures or separated highly anisotropic nanoparticles. Theoretical considerations indicate to the importance of system dimensionality in relation to the energy balance which determines specific features of structure organization in planar charged metallic and magnetic nanostructures. For example, a requirement of Coulomb energy minimum, the possibility of free electron redistribution and strengthened attractive interactions between particles in metallic nanostructures can explain formation of very branchy systems with extremely high "effective perimeter". The obtained experimental and literature data show that system dimensionality, organic ligand nature along with electrostatic and magnetic interactions are most important factors of morphological control of chemically synthesized inorganic nanomaterials. The understanding and appropriate exploitation of these factors can be useful for further developments of efficient nanofabrication techniques based on colloidal and interfacial synthetic methods.

Journal Article↗
PubMed2007

Quantitative study on the microstructure of colloidal fat crystal networks and fractal dimensions.

This paper highlights the most recent progress in the quantitative study on the microstructure and the rheological properties of colloidal fat crystal networks. Several physical models describing the structural hierarchy of the colloidal fat crystal networks are reviewed here, with particular emphasis on fractal model, which can be used to explain the scaling behavior of fat crystal networks. The concept of the fractal dimension has been extensively used in the quantitative study of the microstructure of fat crystal networks and other colloidal networks; however, the relationship between the fractal dimension value and microstructural characteristics remains somewhat nebulous. Recent computer simulation work from our laboratory will be presented relating simulated microstructural features to values of particular measure of fractality including the box-counting, particle counting and Fourier-transform fractal dimensions.

Journal Article↗
PubMed2004

Influences of colloidal stability and electrokinetic property on electrodialysis performance in the presence of silica sol.

Negatively charged silica sol is known to lead to fouling of anion exchange membranes during electrodialysis (ED) as a result of its deposition on the membrane surface. It is known that the fouling potential is related to the physical and electrochemical properties of the silica particles as well as those of the anion exchange membranes. In this study, the properties of the silica sol were characterized in terms of its particle size, turbidity, and zeta potential in order to predict their effects on the electrodialysis performance. In the stability of colloidal particles, the critical coagulation concentrations of silica sol were determined as functions of ionic strength, cation species, and solution pH. In the electrodialysis of NaCl solution containing silica sol with various concentrations of CaCl(2), the colloidal behavior related to deposition and transport was examined during and after electrodialysis. The electrodialysis experiments clearly showed that the deposition and transport of silica sol during electrodialysis were related to the colloidal stability of dispersion.

Journal Article↗
PubMed2004

Nonspherical ZnS colloidal building blocks for three-dimensional photonic crystals.

The asymmetry introduced by a complex or nonspherical basis promotes photonic band gap formation in three-dimensional photonic crystals. However, relatively few techniques have been demonstrated to produce uniform nonspherical colloids for use as photonic crystal bases. Here we expand the menu of basis types with high refractive index by preparing nonspherical zinc sulfide colloids of uniform size and shape. Dimers, trimers, and planar tetramers were precipitated from aqueous solution by the thermal decomposition of thioacetamide in the presence of zinc nitrate, manganese nitrate, and nitric acid. The well-defined morphological types were obtained from suspensions aged for 4-6 h at 26-32 degrees C and then for 20-35 min at 85 degrees C. Stereological techniques were used to analyze SEM images and determine the percentage of each particle class. For example, the quantitative characterization of a particle population prepared at 29 degrees C for 6 h and 85 degrees C for 22 min had the composition 59+/-3% spheres, 31+/-2% dimers, 7+/-1% trimers, 0.4+/-0.2% tetramers, and 2.5+/-0.8% complex clusters (encompasses all other varieties of shape). X-ray diffraction and X-ray photoelectron spectroscopy confirmed the zinc blend crystal structure and the stoichiometric composition of the particles. The refractive index was estimated as 2.25 (413 nm) -2.09 (709 nm) by fitting experimental absorption spectra to curves derived from Mie scattering calculations. This indicated an average porosity approximately 24%. Such colloids offer the potential to form diamond-like lattices with large, stable photonic band gaps.

Journal Article↗
PubMed2004

Development of one-dimensional nanostructures through the crystallization of amorphous colloids.

In this paper we have demonstrated that the crystallization method of amorphous colloids is convenient and feasible in the large-scale production of one-dimensional (1D) nanostructures. For the crystals with highly anisotropic structures, such as orthorhombic, trigonal, and hexagonal crystals, the crystallization generally tends to occur along the (001) axis. The preparation of orthorhombic bismuth sulfide (Bi2S3) nanorods and trigonal selenium ( t-Se) nanowires by the crystallization route was used as typical examples to illustrate the process and mechanism of crystallization. The as-prepared products were characterized with transmission electron microscopy, field-emission scanning electron microscopy, X-ray diffraction, and selected area electron diffraction. Additionally, the detailed crystal growth processes involved in the crystallization of amorphous Bi2S3 colloid were investigated by studying the morphology and structure of intermediates. It demonstrates that the growth of the nanorods is through two key steps: (1) the formation of multiple activated sites on the surface of spherical Bi2S3 colloid and (2) the subsequent preferential growth along these sites.

Journal Article↗
PubMed2004

Self-assembly of spherical colloidal silica along the [100] direction of the FCC lattice and geometric control of crystallite formation.

Opalescent starburst patterns were formed on a convex surface by sedimenting colloidal silica spheres with a low silica volume fraction. The opalescent starburst patterns were also formed by the radial expansion of the meniscus when sedimented samples were slowly dried. The dependence of starburst formation on the rate of sedimentation and drying was experimentally investigated. Self-assembled opals fabricated from colloidal silica spheres grew vertically along the [100] direction of the face-centered cubic lattice. Elongated single-crystal crystallites nearly 1 cm wide and a few centimeters long formed in the curve at the bottom of an ordinary laboratory beaker from sedimenting 200- and 290-nm colloidal silica spheres. The elongated crystallites appear to be the result of an increased sedimentation rate, which creates favorable growth conditions. This is caused by the presence of the curve in the beaker and the spheres' inability to expand into the interior of the beaker before being sedimented. A narrowing of crystallites is shown to result from the competition between neighboring crystallites and large crystallites are shown to result from a lack of competition during their formation.

Journal Article↗
PubMed2004

Concentration-dependent surface-enhanced Raman scattering of 2-benzoylpyridine adsorbed on colloidal silver particles.

Surface-enhanced Raman scattering (SERS) of 2-benzoylpyridine (2-BP) adsorbed on silver hydrosols has been investigated. It has been observed that with a small change in the adsorbate concentration, the SER spectra of 2-BP show significant change in their features, indicating different orientational changes of the different part of the flexible molecule on the colloidal silver surface with adsorbate concentration. The time dependence of the SER spectra of the molecule has been explained in terms of aggregation of colloidal silver particles and co-adsorption and replacement kinetics of the adsorbed solute and solvent molecules on the silver surface. The broad long-wavelength band in the absorption spectra of the silver sol due to solute-induced coagulation of colloidal silver particles is found to be red-shifted with the increase in adsorbate concentration. The surface-enhanced Raman excitation profiles indicate that the resonance of the Raman excitation radiation with the new aggregation band contributes more to the SERS intensity than that with the original sol band.

Journal Article↗
PubMed2004

Validation of cross-flow ultrafiltration for sampling of colloidal particles from aquatic systems.

The use of cross-flow ultrafiltration (CFF) for the isolation of colloids from the bulk aquatic matrices has been increasing over the last decade; however, a thorough validation of each CFF system is needed before its application to natural samples. Laboratory experiments have been conducted to validate a 1-kDa Millipore Pellicon 2 cartridge type CFF system, using a range of molecular probes spiked in natural waters. Using the separation data of these probes, key validation parameters have been calculated, including retention coefficient (RC), concentration factor (cf), colloid concentration, recovery, and mass balance. The permeation behaviour of these molecules has also been studied using a simple permeation model. Results show that good retention (>80%) of high molecular weight (HMW, >1 kDa) molecules and low retention (<20%) of low molecular weight (LMW, <1 kDa) molecules can be achieved at high cf values or over long timescales. In addition, permeation modelling and the calculation of colloid concentration demonstrate the same findings, again recommending high cf values or long timescales for ultrafiltration to minimise the retention of LMW molecules. The retention characteristics of 3-kDa dextran change slightly with salinity. Mass balance calculations show good recoveries for all of the molecules tested. The apparent membrane molecular cut-off of the CFF system has been estimated to be between 2.1 and 2.5 kDa, which is slightly greater than the manufacturer's nominal MW cut-off of 1 kDa.

Journal Article↗
PubMed2004

The shear viscosity of polyampholyte (gelatin) stabilized colloidal dispersions.

A micromechanical model for the zero shear viscosity of polyampholyte-stabilized colloidal dispersions based on the osmotic overlap potential is proposed and tested against model system measurements. This model relates the shear viscosity of polyampholyte-stabilized colloidal dispersions to the oncotic pressure of polyampholyte solutions through an interparticle potential and an effective hard-sphere scaling. The results of viscosity calculations based on independently measured parameters compare favorably to experimental measurements on model, silica dispersions stabilized with adsorbed photographic grade gelatin. The results support a direct link between the capacity of polyampholytes and polyelectrolytes to stabilize dispersions and control dispersion viscosity and their solution oncotic pressure. The model is also demonstrated to provide a master curve for literature data for the zero shear viscosity of polyampholyte stabilized colloidal dispersions.

Journal Article↗
PubMed2005

Size-controlled synthesis of colloidal platinum nanoparticles and their activity for the electrocatalytic oxidation of carbon monoxide.

Using polyvinylpyrrolidone (PVP) as a stabilizing agent, stable colloidal solutions of platinum nanoparticles of different size distributions have been prepared by reducing H2PtCl6 with hydrogen. The UV-vis adsorption peaks at 258 nm due to the adsorption of Pt(IV) species disappear completely, indicating that the Pt(IV) species has been used up and colloidal Pt has been formed. The electrodes have been prepared from aqueous Pt colloids and glassy carbon (GC). The effect of platinum particle size of Pt/GC catalyst electrode on the electrocatalytic oxidation of carbon monoxide has been investigated. The voltammetry shows that a higher potential is needed for the oxidation of absorbed carbon monoxide with a decrease of the platinum particle size for particle sizes larger than 1 nm. But for particle sizes smaller than 1 nm, the potential remains constant while the activity decreases with decreasing the size. The snowlike, well-dispersed, and highly ordered platinum nanoparticles demonstrate high activity in the oxidation reaction of carbon monoxide. The reason may be due to the geometric structure of platinum nanoparticles.

Journal Article↗
PubMed2005

Preparation and properties of colloidal iron dispersions.

We systematically study the properties of dispersions of iron-based colloids synthesized in a broad size range by thermal decomposition of ironcarbonyl using different stabilizing surfactants. The synthesis results in stable dispersions of monodomain magnetic colloids. Our particles appear to consist of an amorphous Fe(0.75)C(0.25) alloy. Sizes of particles coated with modified polyisobutene or oleic acid can be easily controlled in the 2-10 nm range by varying the amounts of reactants. Extensive characterization with various techniques gives particle sizes that agree well with each other. In contrast to dispersions of small particles, which consist of single colloids, dynamic aggregates are present in dispersions of larger particles. On exposure to air, an oxide layer forms on the particle surface, consisting of a disordered Fe(III) oxide.

Journal Article↗
PubMed2006

Monodisperse hollow titania nanospheres prepared using a cationic colloidal template.

Titania-coated polymeric nanoparticles were synthesized based on the cationic colloidal particles which were prepared by surfactant-free emulsion copolymerization of styrene and butylacrylate in the presence of a cationic monomer, methacryloxyethyltrimethyl ammonium chloride (MOTAC) using azobis(isobutylamidine)hydrochloride (AIBA) as an initiator. These cationic particles were stabilized by poly(vinylpyrrolidone) (PVP). Then, these particles were dispersed in ethanol and mixed with titanium(IV) butoxide. Negatively charged titania precursors were rapidly hydrolyzed onto the cationic surfaces of colloidal particles. Subsequently, the samples were heated to 450 degrees C to form anatase TiO2 and to remove the colloidal template, which resulted in hollow nanospheres. The hollow titania particles were characterized with zeta analyzer, transmission electron microscopy, scanning electron microscopy, light scattering, X-ray diffraction, thermogravimetric analysis and FT-IR.

Journal Article↗