Microspheres Online

Everything about microspheres and research utilizing precision spherical particles.

BioCompatability of Metal Coated Spheres

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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:

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High Index of Refraction Retroreflective Glass Microspheres

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Barium Titanate Glass Microspheres are excellent for use as a functional retro reflective additive to paints and coatings. Spheres with sizes of about 50 micron (~0.002 inches) mean diameter provide a small enough size for most coatings while offering a large enough size to reflective a significant amount of light. Barium Titanate Glass Spheres are offered in both partially aluminum coated retro-reflective version for addition into transparent coatings, or as uncoated glass spherical powder for uses in colored paints.

Patent Review: Process for forming hollow glass spheres up to 5mm

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A process for forming hollow glass micro-spheres with walls of controllably variable thickness in a size range of 50 to 5,000 microns, embodying (1) preparation of a water slurry of finely particulated, high temperature and low temperature glass formers; (2) prilling the slurry in a vertical spray drying tower; (3) separating and supporting the individual prilled feed material; (4) heating the feed material to glassification of the high temperature glass former while maintaining appropriate geometry and shell thickness and (5) cooling the finished product. The high temperature glass former is preferably a naturally occurring soda feldspar. The process is particularly adapted to form thicker walled micro-spheres of larger size and high quality.

Advantages of Borosilicate Glass Microspheres in 0.03mm to 0.2mm sizing

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Borosilicate Glass Microbeads
BSGMS 63-75 micron at 40x magnification

High quality glass microspheres for research and development are always in high demand.? In an effort to better serve scientists Cospheric recently added a complete line of high quality borosilicate microspheres, and microbeads.

Borosilicate glass offers? advantages over standard soda lime glass microbeads.

  • Roundness is >90%?? (Soda lime >85%)
  • Density is the lowest of most glasses at 2.2g/cc? (Soda Lime 2.5g/cc)
  • Very low thermal expansion coefficient? 32×10-7/?C?? (for 30-300?C)?? (Soda Lime:? 90×10-7/?C)

The high roundness, and low thermal expansion make borosilicate spheres an excellent candidate for use as spacers in epoxy bond lines, or other applications which require stability over a wide temperature range.

Borosilicate glass spheres are now offered in narrow size ranges from 0.03mm to 0.2mm with greater than 90% of the particles in range.

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Magnetic Microspheres – New Size Ranges Offered

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Cospheric announces new particle size ranges for its BKPMS, Paramagnetic Microsphere product.

Thanks to customer demand for narrower particle size ranges of paramagnetic microspheres. Cospheric has added the following sizes to its extensive inventory of microspheres offered in the dry powder form:

Neutrally Buoyant Particles – What Are They, What Are They Used For, How to Use Them?

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Suspension of microspheres in water enables the visualization and characterization of fluid flow and testing the capability of devices to withstand particulate matter in the fluid stream, ensuring that microspheres do not settle and do not float on the surface. Most of these polymer microspheres are at least moderately opaque and clearly visible in water, clear or translucent liquids.

FDA-Approved Microspheres

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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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Phosphorescent Microspheres – Long Afterglow Particles

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Phosphorescent microspheres in particle sizes 10 to 600 microns are now available from Cospheric LLC. These phosphorescent particles are 90% spherical and appear to be off-white under ordinary daylight or regular room illumination.? However, when the lights are turned off these phosphorescent particles exhibit phosphorescent yellow-green after-glow. The spheres have tight particle size distributions and … Read more

Microspheres in Medical Devices – MDDI Magazine

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What are Microspheres?

The Microsphere of Influence

Published on MDDI Magazine
By: Yelena Lipovetskaya

Why Use Microspheres in Medical Devices?

Properties of Microspheres - Composition
Microspheres in Medical Devices

Microspheres are round microparticles that typically range from 1 to 1000 micron in diameter. Benefits of microspheres in medical devices, pharmaceuticals, and cosmetics are well known due to the microspheres’ ability to encapsulate and deliver active materials. However, there are many other lesser known advantages and functionalities of using micropsheres in medical device design, quality control, manufacturing, and testing.

The typical manufacturing process 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. The resulting particles are often called microcapsules, which are different from solid, non-deformable microspheres.

Solid microspheres are widely used as fillers and spacers in a variety of industries. Microspheres that are 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.

Solid microspheres in medical devices are often used as tracers and challenge particles. In these situations, it is beneficial to use larger microspheres with sphere diameters greater than 50 micron 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.

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Density Marker Beads – Microspheres with Specific gravity of 1.065 and 1.075

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In the biomedical industry researchers are sometimes looking for cells having targeted specific gravities. In order to locate these cells in test tubes it is useful to have colored marker beads which will show where the delineation between specific densities occurs. Two microsphere products having densities of 1.065 g/cc and 1.075 g/cc were recently released. These spheres are offered with density tolerances of ?0.005 g/cc enabling excellent stratification, and bright blue and red coloration for high visibility with the unaided eye.

Microspheres Online

About us:

We are compiling a digital database on everything that has to do with microspheres and creating a destination for scientists working with  precision spherical particles.

What we offer:
  • introduction to microsphere products and their uses;
  • technical information and what specifications are important;
  • overview of published articles and research using microspheres;
  • support in sourcing the right material for your project and more.
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