Everything about Microspheres
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  • Suspension of Hydrophobic Particles in Aqueous Solution – Density Gradients

    Posted on April 10th, 2019 Microsphere Expert
    Fluid Flow Visualization using Microspheres, Spherical Particles

    Fluorescent polyethylene microspheres for flow visualization in aqueous systems. Suspension of beads in aqueous solutions.

    Background Information

    Many materials are hydrophobic (water-fearing) in nature. Due to their non-polar chemical structure, hydrophobic particles want to minimize contact with polar (water) molecules and, as a result, tend to aggregate on the surface of the water and resist going into suspension. This presents a challenge to scientists and engineers who would like to be able to work with hydrophobic particles suspended in aqueous solution.

    Examples of the applications are using fluorescent polyethylene microspheres for flow visualization in aqueous systems, creating density gradients, filtration and contamination control studies.

    Fortunately, there is a simple way to overcome the hydrophobic effect. It is called a surfactant, a detergent, or simply “soap.” Surfactant is a magical molecule that has both hydrophobic and hydrophilic properties, which coats the particles and helps them mix into water. The same mechanism applies when we use soap to wash greasy dishes or stained clothes.

    Selection of the surfactant depends purely on your process and product requirements. Dishwashing liquid works great, so does Simple Green. For scientists working on biological applications we recommend the use of Tween surfactants. Tween is the commercial name for Polysorbate non-ionic surfactants, which are stable, nontoxic, and often used in pharmacological, cosmetic, and food applications. Non-ionic detergents are considered to be “mild” detergents because they are less likely than ionic detergents to denature proteins. By not separating protein-protein bonds, non-ionic detergents allow the protein to retain its native structure and functionality.

    Tween 20 and Tween 80 are frequently used. Both surfactants are yellowish, water-soluble viscous liquids. Primary difference between the two is viscosity. Tween 20 has lower viscosity and is easier to work with.

    Suspension Process

    There are many ways to suspend the particles (e.g. put a few drops of dish detergent into water and shake with the particles).

    The process below is specific for using the minimum amount of Tween for biologically sensitive applications.

    Safety:

    • Gloves and eye protection are to be worn at all times during solution preparation and use.
    • Care should be taken when handling hot objects/liquids and immersion blender.
    • Centrifuge should be properly balanced and allowed to come to a full stop before opening.

    Recommendations:

    • We recommend using distilled water to minimize impurities.
    • We recommend boiling the water to sterilize and to make it easier to disperse a small amount of surfactant uniformly. This also increases shelf-life of prepared solutions and suspensions.
    • We use an immersion blender to disperse the surfactant in water quickly and effectively.

    Process:

    Preparing Tween Solution:
    • Fill a heatproof container with distilled water.
    • Ensure the water level is high enough to cover the immersion blender.
    • Heat water to boiling and leave boiling for 5 minutes.
    • Weigh out 0.1g of Tween per 100ml of water used (creating 0.1% solution).
    • Slowly add Tween to boiled water while mixing with immersion mixer (~30 seconds).
    • Some bubbles will form during mixing.
    • Bubbles will dissipate on cooling and solution will appear clear.
    Suspending particles in Tween solution.
    • Place the desired amount of particles into a container.
    • Dispense prepared Tween solution on top of particles.
    • We recommend at least five times greater volume of solution to the volume of particles.
    • Cover tightly and place containers into a centrifuge.
    • Centrifuge on highest setting for at least 5 minutes.
    • If some particles are still floating on the surface of water, more centrifuging may be necessary.
    • A small quantity of particles may accumulate on the top surface and not enter solution despite additional centrifugation. Typically, these particles will go into suspension over time (hours).
    Other Considerations
    • A greater length of centrifuging or larger volume of Tween solution may be necessary to suspend certain materials and particle sizes.
    • As a 0.1% Tween solution is sufficient for most applications, concentration levels could be raised to support particles that are more resistant to entering solution.
    • Once the particles are suspended, solution can may be diluted further to increase the volume.
    • Particles can be recycled and reused as necessary. The suspension might need to be repeated.
    • If no centrifuge is available, it is possible to shake the container by hand (up and down, upside down) to achieve the same result.

    Here is an example of Cospheric fluorescent beads 150 to 180micron in diameter being dispersed in a pilot bioreactor.

    About Cospheric

    Our extensive product line consists of more than two thousand unique spherical microparticle and nanoparticle products, all developed based on customer demand. We work with each individual customer to find a creative solution for their unique needs ­– tight particle size ranges, wide selection of colors, densities, properties and formulations. We are the sole global supplier for the majority of our products. We developed a disruptive technology which is redefining the microsphere market and creating a new category of precision spherical particles. Our research department is always excited to tackle new challenging projects. Explore at www.Cospheric.com.

    Other Information

    The information contained in this document is correct to the best of our knowledge at the date of publication. It should not be viewed as all inclusive, but as a guide only. It does not represent any guarantee of the properties of the product. Cospheric LLC shall not be held liable for any damage resulting from handling of or from contact with the above product. For these reasons, it is important that product users carry out their own tests to satisfy themselves as to the suitability of the safety precautions for their own intended applications.

  • Fluorescent Microspheres Used for Experiments in Plant Canopies

    Posted on December 19th, 2018 Larisa Lipovetskaya
    Fluorescent Microspheres - Polymer Spheres - 1g/cc

    Fluorescent Microspheres – Polymer Spheres – 1g/cc

    The University of Utah in collaboration with USDA Labs in Corvallis, OR performed five field campaigns in commercial vineyards in Oregon’s Willamette Valley.  Among the methodologies developed over the five-years experiment was the use of fluorescent microsheres as a fungal spore analog.  The microspheres used were inert fluorescing polyethylene micropsheres in four separate colors manufactured by Cospheric.

    The article attached below outlines the technology developed as well as microspheres sampling and meteorological equipment used in the experiments.  The authors of the article conclude that “these techniques have enabled for incredibly detailed research into particle plume dynamics in a vineyard.”

    NMiller_Poster_Methods

     

     

  • 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.