Everything about Microspheres
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  • 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

  • Microspheres for Medical Devices – MDDI Magazine – January 2011

    The Microsphere of Influence

    Published: January 2011, MDDI

    Published on MDDI Magazine
    By: Yelena Lipovetskaya

    Find more content on: Feature, Nano and Microtechnology, Technology, Testing and Inspection

    Microspheres come in many different grades and sizes, and are usually solid particles that are composed of polymers, glass, and ceramics. All images courtesy of COSPHERIC LLC

    Microspheres are round microparticles that typically range from 1 to 1000 μm in diameter. In the pharmaceutical and cosmetics industry, microspheres are well known for their ability to deliver active materials. This process usually involves the microencapsulation of a drug or an active cosmetic ingredient to protect it from the deteriorating effects of the environment or for optimal release and performance in the final product. Active ingredients are released by dissolution of the capsule walls, mechanical rupture (rubbing, pressure, or impact), melting, or digestion processes. Solid microspheres are widely used as fillers and spacers in a variety of industries.

    Microspheres used to manufacture and test medical devices are typically solid particles that are made from robust and stable raw materials such as polymers, glass, and in some cases, ceramics. Different types and grades of microspheres are available and selected based on specific application requirements.

    They are often used as tracers and challenge particles in medical devices. In these situations, it is beneficial to use larger microspheres with sphere diameters greater than 50 μm that are vividly colored (red, blue, black, yellow, or green), since they provide contrast with the background material and visibility to the naked eye in daylight. Colored microspheres are typically used in the testing of filtration media and systems, vial and container cleaning evaluations, flow tracing and fluid mechanics, centrifugation and sedimentation processes, pharmaceutical manufacturing, and contamination control.

    Fluorescent microspheres are recommended for applications that require the use of particles that emit distinctive colors when illuminated by UV light and offer additional sensitivity for observation through the use of microscopes, lasers, and other analytical methods. Examples include microcirculation and biological research, imaging, and flow cytometry. Fluorescent microspheres can be excited and detected by a wide range of methods and are useful as experimental particles for acoustical and optical analytical systems.

    Continue reading “Microspheres for Medical Devices – MDDI Magazine – January 2011” »