Everything about Microspheres
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  • Microspheres Used as a Drug Delivery System

    Posted on December 11th, 2018 Larisa Lipovetskaya

    There has been numerous studies done and articles published in scientific publications about the advantages of microspheres as a drug delivery system vs conventional approach to drug delivery.  Design, Development and Future Application of Microspheres by Divya Rawat , U.K> Singh and Faizi Muzaffar,  Kharvel Subharti College of Pharmacy, published in PharmaTutor discusses the types of microspheres that posses the properties needed for various drug delivery systems, their advantages and limitations.  The micropsheres best suitable to be used in biomedical applications, research and lab experiments are polystyrene.  According to the article: “Polystyrene microspheres are typically used in biomedical applications due to their ability to facilitate procedures such as cell sorting and immune precipitation. Proteins and ligands adsorb onto polystyrene readily and permanently, which makes polystyrene microspheres suitable for medical research and biological laboratory experiments. Polyethylene microspheres are commonly used as 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.”

    Another research paper that discusses advantages and disadvantages of microspheres use for drug delivery, as well as techniques to prepare microsheres and principle behind drug delivery system is Microspheres as Drug Carriers for Controlled Drug Delivery: a Review by Nisha Sharma, Neha Purwar and Prakash Chandra Gupta, University Institute of Pharmacy, C.S.J.M. University, Kanpur, India published in International Journal of Pharmaceutical Sciences and Research.  Polymer microspheres were used for the experiment. The authors conclude that “microspheres are better choice of drug delivery system than many other types of drug delivery system. In future by combining various other strategies, microspheres will find the central and significant place in novel drug delivery, particularly in diseased cell sorting, diagnostics, gene & genetic materials, safe, targeted, specific and effective in-vitro delivery and supplements as miniature version of diseased organ and tissues in the body.”

  • Enabling Breakthroughs with Precision Microspheres

    Posted on October 29th, 2017 Yelena Lipovetskaya

    Yelena Lipovetskaya, the CEO and co-founder of Cospheric LLC, the leading global supplier of precision spherical particles, was recently interviewed on 805conversations podcast which features engaging talks with leaders and thinkers in the 805 region in California. In this podcast, Yelena talks about the company, the foundations, and the path forward. Yelena answers a lot of challenging and informative questions on what is a microsphere, what are the applications and numerous fields of science and technology they are used in, and how precision microspheres enable breakthroughs in so many ways.

  • Particle Image Velocimetry – Particle Density and Neutral Buoyancy

    Posted on August 16th, 2017 Daniel D. Stuart

    Density of particle vs. density of fluid:

    Silver Metal Coated Hollow Glass Microspheres

    Many flow visualizations are done in water but there are a variety of other liquids and even water based solutions that will have differing densities whose velocity fields are being mapped or will be in the future. Therefore, having seed particles to match these differing densities is important to provide neutral buoyancy, one of the most important factors regarding flow conformity.

    With polyethylene spheres contributing a range of densities that provide neutrally buoyant tracers for most water fluid flows thought needs to be directed towards furnishing tracers to match other densities. Gasoline and similar carbon based fluids are an example of areas of fluid flow mechanics where lower density tracer particles are necessary. Silver Coated Hollow Glass Microspheres have the density range to potentially work for many carbon chain liquids, with current densities ranging from .15 g/cc to .75 g/cc and possibly higher. This leaves some room for improvement in the densities between .75 g/cc and .96 g/cc.

    There are many options available for neutrally buoyant microspheres in water. While, other fluids may have more difficulty finding an ideal density tracer, there are options available and scientists are working to provide more unique and targeted tracer particles for use with low density fluids.

  • Particle Image Velocimetry – Particle Size and Distribution

    Posted on August 16th, 2017 Daniel D. Stuart

    Particle size:

    Particle size is connected to many of the other parameters of seed particles in a PIV system. With size affecting visibility, flow conformity, and being integral in relation to pixel size. A rough number for ideal particle size is 1-100um though sizes in the nm and mm’s have been used for certain PIV applications. With smaller sizes being necessary for micro-PIV methods and larger sizes being a requirement for large scale flow visualization. The importance of size is related to how truly the tracer will follow the flow with particle diameter having the largest effect on stokes number, which is a representation of flow tracer fidelity. Though when particle size becomes too small it can be difficult to confirm that the tracer is not being affected by minor currents or other factors within the fluid. Also as size decreases visualizing the spheres can become quite challenging. However, the stokes number can provide a decent representation of how well particles follow the flow. Though, the stokes number is an approximation based on assumptions and therefore can only provide a useful representation rather than a confirmation of tracer fidelity.

    Particle size distribution:

    Fluorescent Red Polyethylene Tracers

    A parameter that should be considered in conjunction with particle size is distribution. As particles in the sizes used for PIV are so small that no meaningful quantity of tracers can be produced in a specific size and rather size ranges need to be considered. With tighter size distributions, there will be less error attributable to differences in visibility of particles and a better approximation of how well each particle being used will conform to the flow. For example fluorescent red polyethylene has multiple size ranges available (10-22um, 10-45um, 10-90um, and 10-150um). With tighter size distributions being more difficult to obtain and as such being more expensive. Raising the question of what the trade off between price and size distribution is. Wide distributions can be used within PIV, however they may necessitate further image processing and may reduce accuracy of measurements. Therefore, there is no perfect size distribution choice. Though, with the understanding of what is available the choice of a correct size and size distribution can be determined.

  • Particle Image Velocimetry – Intro to Tracer Particle Parameters

    Posted on August 9th, 2017 Daniel D. Stuart

    PIV is a vast field with varying techniques and differing areas of research. Techniques vary from 2D PIV, only viewing velocity in a plane of the fluid system, to high speed TOMO PIV which views a 3D area of fluid and can be time resolved allowing for acceleration data to also be obtained. Another difference is that the size of liquid PIV set-ups can range from micron sized micro channels to multi thousand-gallon tanks. While the area being imaged may not vary as much as the

    Barium Sulfate Tracer for X-ray imaging

    systems themselves, it can still differ from units of micro meters to potentially meters. With viewing windows growing as new advancements in science and technology progress, the need for seed particles to match them will grow. One example of this is the rise of helium filled soap bubble seeders that provide an easily visualized 300um bubble for air systems allowing for large areas to be seeded and visualized. Or barium sulfate polyethylene microspheres which are useful due to being a radio contrast agent allowing for visualization via x-ray imaging.

    Therefore, a one solution fits all approach is not feasible when it comes to seed particle selection. As each experiment will have differing size, density, light intensity/visibility, particle material, and seeding concentration needs based on desired results.