Product Code Database
Microparticles are particles between 0.1 and 100 μm in size. Commercially available microparticles are available in a wide variety of materials, including ceramics, glass, polymers, and metals. Microparticles encountered in daily life include pollen, sand, dust, flour, and powdered sugar. The study of microparticles has been called micromeritics, although this term is not very common.
Microparticles have a much larger surface-to-volume ratio than at the macroscale, and thus their behavior can be quite different. For example, metal microparticles can be explosive in air.
are spherical microparticles, and are used where consistent and predictable particle surface area is important.
In biological systems, a microparticle is synonymous with a microvesicles, a type of extracellular vesicle (EV).
A recent study showed that infused, negatively charged, immune-modifying microparticles could have therapeutic use in diseases caused or potentiated by inflammatory monocytes.
Microparticles can also be used during minimally invasive embolization procedures, such as hemorrhoidal artery embolization.
Microspheres can be made from various natural and synthetic materials. Glass microspheres, polymer microspheres, metal microspheres, and ceramic microspheres are commercially available. Solid and hollow microspheres vary widely in density and, therefore, are used for different applications. Hollow microspheres are typically used as additives to lower the density of a material. Solid microspheres have numerous applications depending on what material they are constructed of and what size they are.
Polyethylene, polystyrene and expandable microspheres are the most common types of polymer microspheres.
Polystyrene microspheres are typically used in biomedical applications due to their ability to facilitate procedures such as cell sorting and immunoprecipitation. Proteins and ligands adsorption onto polystyrene readily and permanently, which makes polystyrene microspheres suitable for medical research and biological laboratory experiments.
Polyethylene microspheres are commonly used as a permanent or temporary filler. Lower melting temperature enables polyethylene microspheres to create porous structures in ceramics and other materials. High sphericity of polyethylene microspheres, as well as availability of colored and fluorescent microspheres, makes them highly desirable for flow visualization and fluid flow analysis, microscopy techniques, health sciences, process troubleshooting and numerous research applications. Charged polyethylene microspheres are also used in electronic paper digital displays. Paint and Coatings Industry Magazine, January 1st, 2010 : Opaque Polyethylene Microspheres for the coatings applications Cosmetics and Toiletries, April 2010 Issue: Solid Polyethylene Microspheres for effects in color cosmetics
Expandable microspheres are polymer microspheres that are used as a blowing agent in e.g. puff ink, automotive underbody coatings and injection molding of thermoplastics. They can also be used as a lightweight filler in e.g. cultured marble, waterborne paints and crack fillers/joint compound. Expandable polymer microspheres can expand to more than 50 times their original size when heat is applied to them. The exterior wall of each sphere is a thermoplastic shell that encapsulates a low boiling point hydrocarbon. When heated, this outside shell softens and expands as the hydrocarbon exerts a pressure on the internal shell wall.
Glass microspheres are primarily used as a filler and volumizer for weight reduction, retro-reflector for highway safety, additive for cosmetics and adhesives, with limited applications in medical technology.
Microspheres made from highly transparent glass can perform as very high quality optical microcavities or optical microresonators.
Ceramic microspheres are used primarily as grinding media.
Hollow microspheres loaded with drug in their outer polymer shell were prepared by a novel emulsion solvent diffusion method and spray drying technique.
Microspheres vary widely in quality, sphericity, uniformity, particle size and particle size distribution. The appropriate microsphere needs to be chosen for each unique application.
In 1953, Stanley Miller and Harold Urey demonstrated that many simple biomolecules could be formed spontaneously from inorganic precursor compounds under laboratory conditions designed to mimic those found on Earth before the evolution of life. Of particular interest was the substantial yield of obtained, since amino acids are the building blocks for .
In 1957, Sidney Fox demonstrated that dry mixtures of amino acids could be encouraged to upon exposure to moderate heat. When the resulting peptide, or , were dissolved in hot water and the solution allowed to cool, they formed small spherical shells about 2 μm in diameter—microspheres. Under appropriate conditions, microspheres will bud new spheres at their surfaces.
Although roughly cellular in appearance, microspheres in and of themselves are not alive. Although they do reproduce asexually by budding, they do not pass on any type of genetics material. However they may have been important in the development of life, providing a membrane-enclosed volume which is similar to that of a cell. Microspheres, like cells, can grow and contain a double membrane which undergoes diffusion of materials and osmosis. Sidney Fox postulated that as these microspheres became more complex, they would carry on more lifelike functions. They would become heterotrophs, organisms with the ability to absorb nutrients from the environment for energy and growth. As the amount of nutrients in the environment decreased at that period, competition for those precious resources increased. Heterotrophs with more complex biochemical reactions would have an advantage in this competition. Over time, organisms would evolve that used photosynthesis to produce energy.
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