Everything about Microspheres
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  • Silane and Fluorochemical Coated Glass Spheres

    Solid glass imparts visual and material benefits that cannot be replicated when spheres are made of other materials such as ceramics or polymerics, aluminum oxides, or silicas and mineral fillers. Solid glass refracts [bends] and reflects light. Most ceramics [with exceptions] do not transmit light or exhibit specular [mirror-like] reflection due to their internal crystalline structures and surface irregularities. Instead of being reflected back, the light is “trapped” in the structure and emitted as diffuse or scattered reflectance, which is not as strong or direct as light transmitted through glass, which produces mirror-like reflectance.  Prizmalite glass spheres distributed by Cospheric offer off the shelf pre-coated spheres for enhancing these effects.

    Silane coated solid glass spheres with increased hydrophobicity are offered to improve the dispersion of spheres throughout paints and coatings.  Silane coated spheres are not recommended for pure water solutions as the spheres will be too hydrophobic to wet.

    Fluorochemical Coating is available for paint and coating applications where it is desired to bring the spheres to the top of the surface of the coating.  This is best used in applications where retro reflectance is desired.

    The following products are offered in both Silane and Fluorochemical Coating.
    P2011SL  3-6um mean diameter solid soda lime glass
    P2015SL  8-12um mean diameter solid soda lime glass
    P2050SL  35-45um mean diameter solid soda lime glass
    P2075SL 65-75um mean diameter solid soda lime glass
    P2453BTA 40-60um mean diameter solid barium titanate glass with aluminum shell.

    Solid Glass Spheres:

    • Act as mini-magnifying glasses to deliver visually truer color
    • Clarify and magnify the visual impact of pigments and metallic flakes
    • Create a richer, wetter, deeper look
    • Visually extend expensive color-shift pigments to create cost-effective new looks
    • Prop up other pigments, mica and aluminum flakes
    • Increase exposed surface area and visual impact
    • Facilitate even dispersion of colorants and reflectors
    • Are anti-mottling agents that enhance visual consistency
    • Act as mini-ball bearings to improve material flow and reduce flow lines
    • Provide color consistency from all viewing angles
  • Density Marker Beads

    Cospheric recently added density marker beads in aqueous solution to their range of products.   Available in densities from 1.02 g/ml to 1.13 g/ml.

    The beads come in a variety of colors and densities and ship within one business day.   These beads are small microspheres of very specific particle density that are used to visualize density gradients.  Commonly used in Percoll gradients these beads offer a fast visual indicator for scientists.

    Density Markers Beads are:
    DMB-FGRN-1.02 Fluorescent Green at 1.02g/cc
    DMB-FORG-1.04 Fluorescent Orange at 1.04g/cc
    DMB-RBLU-1.08 Blue at 1.08g/cc
    DMB-FRED-1.09 Fluorescent Red at 1.09g/cc
    DMB-FBLU-1.13 Fluorescent Blue at 1.13g/cc

    Cospheric Density Marker Beads are provided at a 20% concentration in an aqueous solution in 2.5ml vials. Unlike density marker kits which used to be manufactured by GE Healthcare and have been discontinued, the Cospheric’s colored microspheres are ready for use right out of the vial, don’t need to be swollen, will work with any media, do not expire, and do not change density over time.

    Resources on Creating Density Gradients:

    Biotechnology: Theory and Techniques, Volume I (Jones and Bartlett Series in Biology) by Jack Chirikjian and Chirikjian (Jan 1, 1995)
    Pages 45-50 on Density Gradient Centrifugation.

  • High Density Glass Microspheres

    Barium Titanate Glass microspheres are high density solid glass spheres.  At a Density of 4.5g/cc these solid glass spheres can be used for many scientific applications where high density and optical clarity is needed.  In addition to high density they also offer an index of refraction of more than 1.9.

    Bulk quantities are available in 30-100um and 0.3-1.0mm size ranges.

    For experiments requiring the highest precision the beads can be purchased in classified grades offering >90% of the spheres within a specific size range.  Standard Sizes include the narrow ranges below.

    38-45um, 45-53um, 53-63um, 63-75um, 75-90um, 90-106um, 0.25mm-0.3mm, 0.3mm-0.35mm, 0.36mm-0.42mm, 0.43mm-0.5mm, 0.5mm-0.6mm, 0.6mm-0.7mm, 0.71mm to 0.85mm, and 0.85mm to 1.0mm.

    Product pricing and availability can be found under Cospheric’s BTGMS (barium titanate glass microspheres)

  • 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

  • FDA-Approved Microspheres

    What makes a microsphere FDA-approved?

    In order to tell whether the microsphere can be used in cosmetics, food, or medical devices it is important to look at the raw materials that are incorporated into the microsphere during manufacturing process.  For example, unpigmented or clear polyethylene microspheres supplied by Cospheric in sizes from 10 micron to 1000 micron meet the quality requirements of the US FDA as specified in 21 CFR 172.888 and 21 CFR 178.3720.  Specific grade of polyethylene used in manufacturing of these microspheres is  FDA-approved for food applications in chewing gum base, on cheese and raw fruits and vegetables, and as a defoamer in food.

    Color additives are subject to a strict system of approval under U.S. law (FD&C Act), sec. 721; 21 U.S.C. 379e. Color additive violations are a common reason for detaining imported cosmetic products offered for entry into this country. If a product contains a color additive, by law [FD&C Act, Sec. 721; 21 U.S.C. 379e; 21 CFR Parts 70 and 80] you must adhere to requirements for:

    • Approval. All color additives used in cosmetics (or any other FDA-regulated product) must be approved by FDA. There must be a regulation specifically addressing a substance’s use as a color additive, specifications, and restrictions.
    • Certification. In addition to approval, a number of color additives must be batch certified by FDA if they are to be used in cosmetics (or any other FDA-regulated product) marketed in the U.S.
    • Identity and specifications. All color additives must meet the requirements for identity and specifications stated in the Code of Federal Regulations (CFR).
    • Use and restrictions. Color additives may be used only for the intended uses stated in the regulations that pertain to them. The regulations also specify other restrictions for certain colors, such as the maximum permissible concentration in the finished product.

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