Everything about Microspheres
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  • Black Paramagnetic Spheres and Micropsheres 10micron to 1.4mm

    Black polyethylene paramagnetic microspheres are now available in wide selection of particle sizes ranging from 10 micron to 1.4 millimeters. The particles are supplied in dry powder form. No solvents are used in the manufacturing process. Black paramagnetic polymer microspheres have a strong response to magnetic fields and can be manipulated with a magnet. Highly opaque particles with maximum hiding power.

    Paramagnetic microspheres have the ability to increase in magnetization with an applied magnetic field and loose their magnetism when the field is removed. Neither hysteresis nor residual magnetization is observed and that provides the end use two very practical advantages:

    • When the filed is removed, the microspheres demagnetize and re-disperse easily. This property allows efficient washing steps, low background and good reproducibility.
    • The behavior of the microspheres is always the same whatever the magnetization cycles may be. Such behavior is a key point for automated instrument.

    According to Wikipedia, paramagnetic materials have a small, positive susceptibility to magnetic fields. These materials are slightly attracted by a magnetic field and the material does not retain the magnetic properties when the external field is removed. Paramagnetic properties are due to the presence of some unpaired electrons, and from the realignment of the electron paths caused by the external magnetic field.

    Encyclopedia Britanica defines paramagnetism as a kind of magnetism characteristic of materials weakly attracted by a strong magnet, named and extensively investigated by the British scientist Michael Faraday beginning in 1845. Most elements and some compounds are paramagnetic. Strong paramagnetism (not to be confused with the ferromagnetism of the elements iron, cobalt, nickel, and other alloys) is exhibited by compounds containing iron, palladium, platinum, and the rare-earth elements.

    Paramagnetic microparticles are used in numerous applications where they can be manipulated with a magnet, observed and cleaned-up for reuse.

    • Solid Phase Immunoassays
    • Bacteria Detection
    • High Throughput screening
    • Rapid Tests
    • Cell Sorting
    • Biosensors
    • Nucleic Acids Technology
    • Microfluidics
  • Bichromal Janus Particles, Microspheres, Microbeads – Stock selection or Custom-made

    Bichromal (half-white half-black or any other color) Microspheres, Janus Particles

    Bichromal (half-white half-black or any other color) Microspheres, Janus Particles. In this picture - Paramagnetic black microspheres with partial white coating - Magnification 40x.

    Cospheric offers unique capability to manufacture Janus microspheres and microparticles with partial coatings and dual functionality. Currently half-shell or hemispherical coatings can be applied to any sphere (glass, polymer, ceramic) in sizes 45micron in diameter and higher. Coatings can be customized for any color and coverage of between 20% to 60% of the sphere. Each coating is custom formulated for color, charge, magnetic, electric, and surface properties, and solvent resistance per customers’ needs.

    Half-coated glass microspheres - Partial coating on glass particles

    Half-coated glass microspheres - Partial coating on glass particles. In this picture - Soda lime glass microspheres with partial red coating - Magnification 40x.

    Hemispherical coatings of less than 1 micron with tolerances as low as 0.25 micron have been routinely demonstrated.  Color combinations are truly unlimited. White, black, silver, blue, green, red, yellow, brown, purple as well as transparent microspheres have been made. Sphericity of greater than 90% and custom particle size ranges are offered.

    We have successfully coated solid and hollow glass microsphere, including soda-lime, borosilicate, and barium titanate glass microspheres. We have also coated on silver.

    Half-coated Microspheres

    Half-coated Microspheres

    Optically anisotropic spheres and janus particles with magnetic half-shells have been originally developed for applications in electronic displays, such as e-paper, but are now widely used in numerous applications in diagnostics, medical research, microscopy and biotechnology, as well as electronics, due to their ability to orient themselves in response to electromagnetic field and show a visual response. This is achieved by making spheres both bipolar and bichromal, with dipole precisely aligned with two differently colored hemispheres. As the spheres align themselves, the viewer will observe the color of one hemisphere, while the other hemisphere will be hidden from view, providing an obvious strong visible indication of the presence of the field or other stimuli.  In alternating electromagnetic field, these microspheres have been proven to spin at hundreds of times per second.

  • Negatively-charged Yellow Microparticles – Back in Stock

    Highly Negative Charged Microspheres - Polyethylene, Selection of Sizes 5 to 500um

    Highly Negative Charged Microspheres - Polyethylene, Selection of Sizes 5 to 500um, 1.0g/cc

    Cospheric’s neutrally-buoyant highly charged yellow microspheres have a strong negative charge and are used by scientists in medical technology, biotechnology, applied physics and research. Precise particles with known density of 1.0g/cc that behave in a known way are useful as a model particles in simulation experiments.  Particles in a range of diameters from 5micron to 500micron(0.5mm) are currently back in stock.

    Bright yellow polymer microparticles of high sphericity are spherical polyethylene beads that are specifically designed with density ~1.0g/cc for suspension in fresh water,  serving as seed or tracer particles and enabling flow visualization and Particle Image Velocimetry PIV analysis of fluid flow in a device. It is often advantageous to color code the particles by size to better understand which part of the process the spheres of the specific size were able to pass through, or where the contamination in the process is coming from. Microspheres are supplied in dry powder form and are color stable in solution. No solvents are used in the manufacturing process. Polyethylene is inert to most solvents.

    Cospheric also offers unique capability to manufacture Bichromal janus microspheres and microparticles with partial coatings and potentially dual functionality. Currently half-shell or hemispherical coatings can be applied to any sphere (glass, polymer, ceramic) in sizes 45micron in diameter and higher. Coatings can be customized for any color and coverage of between 20% to 60% of the sphere. Each coating is custom formulated for color, charge, magnetic, electric, and surface properties, and solvent resistance per customers’ needs. Hemispherical coatings of less than 1 micron with tolerances as low as 0.25 micron have been routinely demonstrated.  Color combinations are truly unlimited. White, black, silver, blue, green, red, yellow, brown, purple as well as transparent microspheres have been made. Sphericity of greater than 90% and custom particle size ranges are offered.

    It would be interesting to combine these highly charged yellow microspheres with a partial paramagnetic black coating and investigate the behavior of these spheres in electromagnetic field.

  • BioCompatability of Metal Coated Spheres

    For those scientists who are looking to use silver coated materials such as silver coated microspheres in biomedical applications, it is important to understand whether they are bio-compatable.  A selection of abstracts and article references related to the biocompatability of silver follow:

    The Biocompatibility of Silver2

    The experiments reported have referred to some of the characteristics of the biocompatibility of Ag. Silver has been shown to display interactions with albumin, as an example of a plasma protein, quite different from those of most metals. Such studies shed further light on the complex issue of protein adsorption on biomaterials. It has also been demonstrated that Ag at concentrations < 1 ppm exerts a considerable influence on the activity of lactate dehydrogenase, this effect being reversed in the presence of albumin. A significant but transient increase in blood levels of Ag following intramuscular implantation of the metal has been observed. This is not reflected in any raised urine level. It is proposed that the richly vascular tissue immediately surrounding the implant in the acute phase of the response gives rise to the transient increase, but a subsequent decrease in vascularity reduces this possibility. It appears that Ag released from implants following this initial period substantially remains in the local area.2

    Lack of toxicologocial side-effects in silver-coated megaprostheses in humans1

    Deep infection of megaprostheses remains a serious complication in orthopedic tumor surgery. Furthermore, reinfection gets a raising problem in revision surgery of patients suffering from infections associated with primary endoprosthetic replacement of the knee and hip joint. These patients will need many revision surgeries and in some cases even an amputation is inevitable. Silver-coated medical devices proved their effectiveness on reducing infections, but toxic side-effects concerning some silver applications have been described as well. Our study reports about a silver-coated megaprosthesis for the first time and can exclude side-effects of silver-coated orthopedic implants in humans. The silver-levels in the blood did not exceed 56.4 parts per billion (ppb) and can be considered as non-toxic. Additionally we could exclude significant changes in liver and kidney functions measured by laboratory values. Histopathologic examination of the periprosthetic environment in two patients showed no signs of foreign body granulomas or chronic inflammation, despite distant effective silver concentrations up to 1626 ppb directly related to the prosthetic surface. In conclusion the silver-coated megaprosthesis allowed a release of silver without showing any local or systemic side-effects.1

    Specific Article References for the biocompatability of silver are below: See the References

  • Patent Review: Use of Adsorbent Carbon Microspheres for Treatment of Irritable Bowel Syndrome

    United States Patent 7,749,497 was recently issued to Ocera Therapeutics, Inc. (San Diego, CA) regarding the use of adsorbent carbon microspheres for the treatment of irritable bowel syndrome.

    The patent invention primarily describes the use of adsorbent carbon microspheres for the treatment of irritable bowel syndrome and symptoms associated with it.  Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by altered bowel habits without the presence of detectable structural abnormalities. IBS is fairly common and makes up 20-50% of visits to gastroenterologists.  Most commonly, patients have abdominal pain associated with altered bowel habits that consist of constipation, diarrhea, or both. The other group consists of patients with painless diarrhea.

    One embodiment disclosed herein includes a method of treating one or more symptoms of irritable bowel syndrome by  administering to the subject adsorbent carbon microspheres with a particle size of 0.01mm to about 2 mm to reduce the abdominal discomfort or pain. In one embodiment, the amount of the adsorbent carbon microspheres is sufficient to achieve at least about a 50% reduction in the number of days the subject experiences abdominal pain or discomfort.

    In some of the embodiments, the adsorbent carbon microspheres have a particle size of about 0.05mm to about 0.8 mm. In some of the above embodiments, the adsorbent carbon microspheres have a specific surface area of about 700 m.sup.2/g or more as determined by a BET method. In some of the above embodiments, the adsorbent carbon microspheres have a specific surface area of about 700 m.sup.2/g to about 2500 m.sup.2/g as determined by a BET method.

    Microsphere Manufacturing Process:

    First, a dicyclic or tricyclic aromatic compound or a mixture thereof having a boiling point of 200.degree. C. or more is added as an additive to a pitch such as a petroleum pitch or a coal pitch. The whole is heated and mixed, and then shaped to obtain a shaped pitch. Thereafter, the shaped pitch is dispersed and granulated in hot water at 70 to 180.degree. C., with stirring, to obtain a microspherical shaped pitch. The aromatic additive is extracted and removed from the shaped pitch by a solvent having a low solubility to the pitch but a high solubility to the additive. The resulting porous pitch is oxidized by an oxidizing agent to obtain a porous pitch subject to heat infusibility. The resulting infusible porous pitch is treated at 800 to 1000.degree. C. in a gas flow such as steam or carbon dioxide gas reactive with carbon to obtain a porous carbonaceous substance.

    The resulting porous carbonaceous substance is then oxidized in a temperature range of 300 to 800.degree. C., preferably 320 to 600.degree. C., in an atmosphere containing 0.1 to 50% by volume, preferably 1 to 30% by volume, particularly preferably 3 to 20% by volume, of oxygen. The substance is thereafter reduced in a temperature range of 800 to 1200.degree. C., preferably 800 to 1000.degree. C., in an atmosphere of a non-oxidizable gas to obtain the final product. More details of suitable production processes and suitable products may be found in U.S. Pat. Nos. 4,681,764 and 6,830,753 and U.S. Application Publication No. 2005/0112114, filed May 26, 2005, all of which are incorporated herein by reference in their entirety. Suitable adsorbent carbon microspheres are commercially available from Kureha Corp., and is sold in Japan under the trade name KREMEZIN.RTM. (also known as AST-120).

    Administration of the Microspheres to the Patient:

    For use as described herein, adsorbent carbon microspheres may be administered to the gut of a subject by any suitable means. In one embodiment, the carbon is administered orally. Formulations for oral administration may include, but are not limited to, free flowing microspheres, granules, tablets, sugar-coated tablets, capsules, suspensions, sticks, divided packages, or emulsions. In the case of capsules, gelatin capsules, or if necessary, enteric capsules may be used. The oral dosage administered to a subject may be any amount suitable to achieve the desired therapeutic result. In some embodiments, the oral dosage in the case of a human is about 1 to 20 g of the adsorbent per day.