Cheng, A. L., Pahlevan, N. M., Rinderknecht, D. G., Wood, J. C., & Gharib, M. (2018). Experimental Investigation of the Effect of Non-Newtonian Behavior of Blood Flow in the Fontan Circulation. European journal of mechanics. B, Fluids, 68, 184–192.

  • Particle image velocimetry was used to examine flow behavior at two different cardiac outputs and two caval blood flow distributions. Pressure and flow rates were measured at each inlet and outlet. Velocity, shear strain, and shear stress maps were derived from velocity data. A solution of 45% glycerol in water by volume was used as a control Newtonian fluid with viscosity of 3.5 cP. The density of the glycerol solution was 1099.3 kg/m3. For the PIV measurements, both fluids were seeded with 10-45 µm fluorescent polyethylene microspheres with 532 nm excitation and 605 nm emission peaks.

Mengüç, Y., Röhrig, M., Abusomwan, U., Hölscher, H., & Sitti, M. (2014). Staying sticky: contact self-cleaning of gecko-inspired adhesives. Journal of the Royal Society, Interface, 11(94), 20131205.

  • Embedding of particles between adjacent fibres was observed for particles with diameter smaller than the fibre tips, and further studied as a temporary cleaning mechanism. By incorporating contact self-cleaning capabilities, real-world applications of synthetic gecko adhesives, such as reusable tapes, clothing closures and medical adhesives, would become feasible. In the experiments, glass microspheres with diameters ranging from 3 to 215 µm were used as contaminants. The spheres used included Cospheric glass microspheres (SLGMS 45–53 µm).

Gerdes, Z., Ogonowski, M., Nybom, I., Ek, C., Adolfsson-Erici, M., Barth, A., & Gorokhova, E. (2019). Microplastic-mediated transport of PCBs? A depuration study with Daphnia magna. PloS one, 14(2), e0205378.

  • The effect of microplastic on the PCB removal in planktonic animals was evaluated by exposing the cladoceran Daphnia magna with a high body burden of polychlorinated biphenyls (PCB 18, 40, 128 and 209) to a mixture of microplastic and algae; daphnids exposed to only algae served as the control. The microplastics (fluorescent green microspheres, FMG-1.3 1–5 µm, a proprietary polymer with density of 1.3 g cm-3 and a melting point of 290°C) was purchased from Cospheric.

Peterson, A. W., Halter, M., Tona, A., & Plant, A. L. (2014). High resolution surface plasmon resonance imaging for single cells. BMC cell biology, 15, 35.

  • This study provides an experimental basis for characterizing the resolution of an SPR imaging system in the lateral and distal dimensions and demonstrates a novel approach for resolving sub-micrometer cellular structures by SPRI. The SPRI resolution here is distinct in its ability to visualize subcellular structures that are in proximity to a surface, which is comparable with that of total internal reflection fluorescence (TIRF) microscopy but has the advantage of no fluorescent labels. Poly(methyl methacrylate) (PMMA) microspheres (n=1.48, diameter 63 µm to 75 µm) were used for the project.

Sanchez, L., Yi, Y., & Yu, Y. (2017). Effect of partial PEGylation on particle uptake by macrophages. Nanoscale, 9(1), 288–297.

  • Owing to the surface asymmetry, Janus particles that are internalized enter macrophage cells via a combination of ligand-guided phagocytosis and macropinocytosis. By spatially segregating PEGs and ligands for targeting T cells on Janus particles, we demonstrate that the Janus particles bind T cells uni-directionally from the ligand-coated side, bypassing the hindrance from the PEGs on the other hemisphere. The results reveal a new mechanistic understanding on how a spatial coating of PEGs on particles changes the phagocytosis of particles. Monodisperse silica particles of 500 nm, 1.23 µm and 1.57 µm were used. Silica nanoparticles of diameter 500 nm were purchased from Cospheric LLC for this project.

Bringer, A., Cachot, J., Prunier, G., Dubillot, E., Clérandeau, C., & Hélène Thomas (2020). Experimental ingestion of fluorescent microplastics by pacific oysters, Crassostrea gigas, and their effects on the behaviour and development at early stages. Chemosphere, 254, 126793.

  • Plastics are persistent synthetic polymers that accumulate as waste in the marine environment. Microplastics (MPs, <5 mm) can be found either as microbeads in body care and some industrial products or as plastic debris through degradation. Plastic microbeads (1-5 µm, fluorescent, Cospheric) were used to characterise the MP ingestion and determine their potential harmful effects on both the swimming behaviour and development of oyster D-larvae (Crassostrea gigas).

van den Hoven, A. F., Lam, M. G., Jernigan, S., van den Bosch, M. A., & Buckner, G. D. (2015). Innovation in catheter design for intra-arterial liver cancer treatments results in favorable particle-fluid dynamics. Journal of experimental & clinical cancer research : CR, 34(1), 74.

  • Fluid-particle dynamics are still inadequately understood, and the potential effects of catheter design and position remain unknown. The aim of this study is to enhance our understanding of this complex interplay by comparison of microsphere administrations with an ARC and SMC in the controlled environment of an experimental vascular model. The main objective of experiments with the fluorescent microspheres was to document the particle outflow pattern for qualitative analysis. Fluorescent red polyethylene microspheres (Cospheric LLC, Santa Barbara, Ca, USA) with a density of 1.20 g/cc and size of 27–32 µm was used. Fluorescent illumination of these microspheres is induced at a wavelength of 300–550 nm. The fluorescent microspheres were suspended in a tween surfactant solution (Tween 20) to prevent aggregation, and administered with 30 ml of water.

Zhang, Y., Liu, J., Yang, B., Zheng, Y., Yao, M., Sun, M., Xu, L., Lin, C., Chang, D., & Tian, F. (2018). Ginkgo biloba Extract Inhibits Astrocytic Lipocalin-2 Expression and Alleviates Neuroinflammatory Injury via the JAK2/STAT3 Pathway After Ischemic Brain Stroke. Frontiers in pharmacology, 9, 518.

  • In the present study, researchers examined the neuroprotective and anti-inflammatory effects of Ginkgo biloba extract (EGB), a well-known extract with potential immunoregulatory properties in the nervous system. Fluorescent Yellow Microspheres (106–212 µm in diameter, UVPMS-BY2, Cospheric, United States) were suspended in rat serum with 1 mg/ml, and 0.2 mL of this suspension was injected into the right internal carotid artery. After the injection, the vascular clamps occluding the right external and common carotid arteries were released, and then, the puncture wound was closed with suture strings. Blood flow to the brain by the right external and common carotid arteries recommenced after 2–3 s. Rats in the sham group were injected with the same volume of rat serum but without microspheres.

Rozynek, Z., Mikkelsen, A., Dommersnes, P., & Fossum, J. O. (2014). Electroformation of Janus and patchy capsules. Nature communications, 5, 3945.

  • Janus and patchy particles have designed heterogeneous surfaces that consist of two or several patches with different materials properties. These particles are emerging as building blocks for a new class of soft matter and functional materials. Here the researchers introduce a route for forming heterogeneous capsules by producing highly ordered jammed colloidal shells of various shapes with domains of controlled size and composition. Fluorescent PE particles (UVPMS-BY2 45–53µm) were purchased from Cospheric LLC.

Tan, S. G., Kim, S., Hon, J. K., & Leo, H. L. (2016). A D-Shaped Bileaflet Bioprosthesis which Replicates Physiological Left Ventricular Flow Patterns. PloS one, 11(6), e0156580.

  • Prior studies have shown that in a healthy heart, there exist a large asymmetric vortex structure that aids in establishing a steady flow field in the left ventricle. However, the implantation of existing artificial heart valves at the mitral position is found to have a negative effect on this physiological flow pattern. An in-vitro experiment using two dimensional particle velocimetry imaging was carried out to determine the hemodynamic performance of the new bileaflet design and then compared to that of the well-established St. Jude Epic valve which functioned as a control in the experiment. The flow loop was seeded with orange fluorescent particles with an approximate density of 1000 Kg/m3 (Cospheric LLC, Santa Barbara, CA).

Kurup, G. K., & Basu, A. S. (2012). Field-free particle focusing in microfluidic plugs. Biomicrofluidics, 6(2), 22008–2200810.

  • Particle concentration is a key unit operation in biochemical assays. Although there are many techniques for particle concentration in continuous-phase microfluidics, relatively few are available in multiphase (plug-based) microfluidics. Existing approaches generally require external electric or magnetic fields together with charged or magnetized particles. This paper reports a passive technique for particle concentration in water-in-oil plugs which relies on the interaction between particle sedimentation and the recirculating vortices inherent to plug flow in a cylindrical capillary. The bead suspension consists of deionized water containing soda-lime solid glass beads with mean diameter 38µm and a D50 distribution ranging from 34–42µm (Cospheric).

Chekkoury, A., Nunes, A., Gateau, J., Symvoulidis, P., Feuchtinger, A., Beziere, N., Ovsepian, S. V., Walch, A., & Ntziachristos, V. (2016). High-Resolution Multispectral Optoacoustic Tomography of the Vascularization and Constitutive Hypoxemia of Cancerous Tumors. Neoplasia (New York, N.Y.), 18(8), 459–467.

  • In this study, the scientists implement an innovative high-resolution optoacoustic mesoscopy for imaging the vasculature and tissue oxygenation within subcutaneous and orthotopic cancerous implants of mice in vivo through acquisition of tomographic projections over 180° at a central frequency of 24 MHz. Cospheric microspheres of 200 µm in diameter were used.

Miller, B., Jimenez, M., & Bridle, H. (2016). Cascading and Parallelising Curvilinear Inertial Focusing Systems for High Volume, Wide Size Distribution, Separation and Concentration of Particles. Scientific reports, 6, 36386.

  • Here the scientists present a strategy for achieving rapid high volume processing with stacked and cascaded inertial focusing systems, allowing for separation and concentration of particles with a large size range, demonstrated here from 30µm–300µm. Beads above 5µm were sourced from Cospheric.

Deán-Ben, X. L., & Razansky, D. (2013). Functional optoacoustic human angiography with handheld video rate three dimensional scanner. Photoacoustics, 1(3-4), 68–73.

  • Scientists report on development of a portable clinical system for three-dimensional optoacoustic visualization of deep human tissues at video rate. Characterization of the spatial resolution performance of the hand-held scanner was done using an agar phantom containing a 50 µm diameter black absorbing microsphere (Cospheric LLC, Santa Barbara, CA). The microsphere was positioned around the geometrical center of the spherical detection array and the phantom was moved in order to characterize the resolution of the system in different directions.

Watts, E., Zhao, Y., Dhara, A., Eller, B., Patwardhan, A., & Sinai, A. P. (2015). Novel Approaches Reveal that Toxoplasma gondii Bradyzoites within Tissue Cysts Are Dynamic and Replicating Entities In Vivo. mBio, 6(5), e01155-15.

  • Despite the fact that bradyzoites are considered replicatively dormant, the scientists find evidence for cyclical, episodic bradyzoite growth within tissue cysts in vivo. These findings directly challenge the prevailing notion of bradyzoites as dormant nonreplicative entities in chronic toxoplasmosis and have implications on our understanding of this enigmatic and clinically important life cycle stage. Calibration of the Percoll gradient using colored beads of known densities was performed utilizing Cospheric density marker beads.

Wan, Y., Liu, Y., Allen, P. B., Asghar, W., Mahmood, M. A., Tan, J., Duhon, H., Kim, Y. T., Ellington, A. D., & Iqbal, S. M. (2012). Capture, isolation and release of cancer cells with aptamer-functionalized glass bead array. Lab on a chip, 12(22), 4693–4701.

  • A Hele-Shaw device with aptamer functionalized glass beads is designed, modeled, and fabricated to efficiently isolate cancer cells from a cellular mixture. The glass beads are functionalized with anti-epidermal growth factor receptor (EGFR) aptamer and sit in ordered array of pits in PDMS channel. A PDMS encapsulation is then used to cover the channel and flow through cell solution. The beads capture cancer cells from flowing solution depicting high selectivity. The covalent immobilization of capture probe DNA onto 50 µm diameter Glass Beads (Cospheric) was achieved using described method.

Zhou, J., Kulasinghe, A., Bogseth, A., O'Byrne, K., Punyadeera, C., & Papautsky, I. (2019). Isolation of circulating tumor cells in non-small-cell-lung-cancer patients using a multi-flow microfluidic channel. Microsystems & nanoengineering, 5, 8.

  • Numerous microfluidic platforms have been developed in the past few years to capture these rare cells in patient bloodstream for deciphering the critical information needed. However, the practical need for a high-quality method of CTC isolation remains to be met. Herein, the scientists demonstrate a novel multi-flow microfluidic device that is able to sensitively provide high purity (>87%) of separation outcome without labeling. Microparticles (Cospheric LLC, Santa Barbara, CA, USA) with continuous size distribution (2–32µm) were used to characterize the cuff-off size of the microchannel. These particles are made of PMMA and have a density of ~1.2g/cc.

Zhang, S., Juvert, J., Cooper, J. M., & Neale, S. L. (2016). Manipulating and assembling metallic beads with Optoelectronic Tweezers. Scientific reports, 6, 32840.

  • Optoelectronic tweezers (OET) or light-patterned dielectrophoresis (DEP) has been developed as a micromanipulation technology for controlling micro- and nano-particles with applications such as cell sorting and studying cell communications. The metallic microspheres used in this work are silver-coated PMMA beads with diameters around 50µm (size range: 45µm to 53µm) and an average silver-shell thickness of 250nm (Cospheric, PMPMS-AG-1.53). The metallic microspheres were added to a solution, consisting of deionized water with 0.05% volume ratio of non-ionic surfactant ‘TWEEN 20.’

Blair, R. M., Waldron, S., Phoenix, V. R., & Gauchotte-Lindsay, C. (2019). Microscopy and elemental analysis characterisation of microplastics in sediment of a freshwater urban river in Scotland, UK. Environmental science and pollution research international, 26(12), 12491–12504.

  • Understanding of the sources, fate, and impact of microplastics (MPs, <5 mm) remains limited, particularly in freshwater environments, while limited comparability across available surveys hinders adequate monitoring and risk assessment of these contaminants. Here, the distribution of microscopic debris in an urban river close to the marine environment in the West of Scotland was investigated to assess concentration and distribution of primary and secondary MPs. Polyethylene microbeads (0.71–0.85 mm diameter, density=0.96 g cm-3), polypropylene microbeads (2.45 mm diameter, density=0.866 g cm-3) and polystyrene microbeads (4.4 mm diameter, density=1.048 g cm-3) were purchased from Cospheric LLC (Santa Barbara, California) to be used to mimic primary MPs.

Esteki, M. H., Alemrajabi, A. A., Hall, C. M., Sheridan, G. K., Azadi, M., & Moeendarbary, E. (2020). A new framework for characterization of poroelastic materials using indentation. Acta biomaterialia, 102, 138–148.

  • In most studies the poroelastic properties, including elastic modulus, Poisson ratio and poroelastic diffusion coefficient, are extracted by assuming an instantaneous step indentation. However, exerting step like indentation is not experimentally possible and usually a ramp indentation with a finite approach velocity is applied. Moreover, the poroelastic relaxation time highly depends on the approach velocity in addition to the poroelastic diffusion coefficient and the contact area. Here, we extensively studied the effect of indentation velocity using finite element simulations which has enabled the formulation of a new framework based on a master curve that incorporates the finite rise time. The nominal spring constant of 2.5–3 N m-1 and 25 µm radius glass beads (Cospheric) were used to indent the softest hydrogels (0.6% agarose) of 30 mm diameter and 5 mm thickness, submerged in PBS solution.

Hankins, C., Duffy, A., & Drisco, K. (2018). Scleractinian coral microplastic ingestion: Potential calcification effects, size limits, and retention. Marine pollution bulletin, 135, 587–593.

  • This study investigated calcification effects, size limits, and retention times of microbeads and microfibers in two Caribbean species, Montastraea cavernosa and Orbicella faveolata Coral fragments (n=10 per species for each of five treatments) were exposed to three microbeads in each of four size classes of uncured, polyethylene microbeads (Cospheric®) of the following treatments: (1) 212–250 µm, (2) 425–500 µm, (3) 850–1000 µm, (4) 1.7–2.0 mm, (5) 2.4–2.8 mm, and (6) a control group not exposed to microbeads. Ten M. cavernosa and ten O. faveolata fragments were exposed to three uncured, fluorescent, polyethylene 425–500 µm microbeads (Cospheric®).

Ogonowski, M., Schür, C., Jarsén, Å., & Gorokhova, E. (2016). The Effects of Natural and Anthropogenic Microparticles on Individual Fitness in Daphnia magna. PloS one, 11(5), e0155063.

  • Both small plastic fragments (microplastics, MPs) produced by degradation of larger plastic waste (secondary MPs; SMPs) and microscopic plastic spheres used in cosmetic products and industry (primary MPs; PMPs) are ubiquitously present in the environment. Scientists manipulated food levels (0.4 and 9 µg C mL-1) and MP or kaolin contribution to the feeding suspension (<1 to 74%) and evaluated effects of MPs and kaolin on food uptake, growth, reproductive capacity of the daphnids, and maternal effects on offspring survival and feeding. As PMPs, spherical fluorescent, plastic beads ranging 1–5 µm with a mean of 4.1 ± 1.0 µm (mean equivalent spherical diameter, ESD) and a density of 1.3 g cm-3 (Cospheric LLC, Goleta, USA) were used. Secondary MPs were prepared by grinding 1 mm fluorescent polyethylene beads with a density of 1.0 g cm-3 (Cospheric LLC, Goleta, USA) in liquid nitrogen using a Retsch cryomill (Retsch, Düsseldorf, Germany).

Felten, V., Toumi, H., Masfaraud, J. F., Billoir, E., Camara, B. I., & Férard, J. F. (2020). Microplastics enhance Daphnia magna sensitivity to the pyrethroid insecticide deltamethrin: Effects on life history traits. The Science of the total environment, 714, 136567.

  • The aim of the study was to investigate the influence of microplastics (MPs) on the ecotoxicity of common contaminants of aquatic ecosystems. As a model contaminant, the hydrophobic pesticide deltamethrin (DM) was chosen, and its effects on life history traits of Daphnia magna were studied in the presence or absence of polyethylene MPs. According the manufacturer (Cospheric, Santa Barbara, CA, USA) MPs were spherical (1-4 µm in diameter), had a density of 0.96 g/cm-3 and were without any solvent.

Barboza, L., Vieira, L. R., Branco, V., Carvalho, C., & Guilhermino, L. (2018). Microplastics increase mercury bioconcentration in gills and bioaccumulation in the liver, and cause oxidative stress and damage in Dicentrarchus labrax juveniles. Scientific reports, 8(1), 15655.

  • The knowledge on the toxicity of mixtures containing microplastics and other contaminants to marine species is still scarce. The main goals of this study were to investigate the oxidative stress and lipid oxidative damage potentially induced by 96h of exposure to mercury (0.010 and 0.01mg/L), microplastics (0.26 and 0.69mg/L), and mixtures of the two substances (same concentrations, full factorial) in the gills and liver of D. labrax juveniles, and the possible influence of microplastics on mercury bioconcentration (gills) and bioaccumulation (liver). Fluorescent red polymer microspheres (1–5µm diameter) were used as microplastics particles and were purchased from Cospheric – Innovations in Microtechnology (USA). According to manufacturer indications, 1mg of the product contains about 1.836E+8 spheres (estimate made for an average of 2µm diameter).

Mason, S. A., Welch, V. G., & Neratko, J. (2018). Synthetic Polymer Contamination in Bottled Water. Frontiers in chemistry, 6, 407.

  • Eleven globally sourced brands of bottled water, purchased in 19 locations in nine different countries, were tested for microplastic contamination using Nile Red tagging. Of the 259 total bottles processed, 93% showed some sign of microplastic contamination. After accounting for possible background (lab) contamination, an average of 10.4 microplastic particles >100 um in size per liter of bottled water processed were found. As the “Galaxy Count” software was created specifically for this project in order to verify its accuracy four solutions were created using DI water containing 0, 20, 50 or 100 polyethylene microspheres (Cospheric, PE micropheres, D = 1.25 g mL-1, 75–90 um diameter).

Behrens, M. R., Fuller, H. C., Swist, E. R., Wu, J., Islam, M. M., Long, Z., Ruder, W. C., & Steward, R., Jr (2020). Open-source, 3D-printed Peristaltic Pumps for Small Volume Point-of-Care Liquid Handling. Scientific reports, 10(1), 1543.

  • These microfluidic devices often are designed to operate with peripheral equipment for liquid handling that increases the cost and complexity of these systems and reduces their potential for widespread adoption in low resource healthcare applications. Here, we present a low-cost (~$120), open-source peristaltic pump constructed with a combination of three dimensional (3D)-printed parts and common hardware, which is amenable to deployment with microfluidic devices for point-of-care diagnostics. The pump was programmed with the Arduino IDE to generate custom responses to an operator controlled switch. Fluid flow was visualized by placing a cellulose acetate 0.91mm diameter red sphere (Cat. No. CAS-RED-1.3 0.91+/-0.05mm-100, Cospheric) into a glass capillary with an inner diameter of 1mm (Cat No. 13-678-20A, Fisher Scientific).

Ando, Y., Sakurai, T., Koida, K., Tei, H., Hida, A., Nakao, K., Natsume, M., & Numano, R. (2016). In vivo bioluminescence and reflectance imaging of multiple organs in bioluminescence reporter mice by bundled-fiber-coupled microscopy. Biomedical optics express, 7(3), 963–978.

  • This is the first report of in vivo BLI of the brain and multiple organs in luciferase-reporter mice using bundled-fiber optics. With reflectance imaging, the structures of blood vessels and organs can be seen clearly with light illumination, and it allowed identification of the structural details of bioluminescence images. Fluorescent beads 10 µm in diameter (10 – 15 µm, FluoSpheres polystyrene microspheres, orange fluorescent 540 nm/560 nm, F8833; Molecular Probes, Eugene, OR) or 50 µm (45 – 53 µm, Fluorescent Orange Polyethylene Microspheres, UVPMS-BO-1.00 45 – 53 µm – 5 g; Cospheric, Santa Barbara, CA) were scattered on a glass-based dish coated with poly-d-lysine at a low density. The bead diameter, 10 – 15 µm, is similar to that of an ordinary cell. Fluorescent beads in air or water were excited by the fluorescence microscope (ECLIPSE Ti; Nikon, Tokyo, Japan) with a light source (Intensilight C-HGFIE; Nikon) through a band pass filter (540 nm/25 nm).

Nathamgari, S. S., Dong, B., Zhou, F., Kang, W., Giraldo-Vela, J. P., McGuire, T., McNaughton, R. L., Sun, C., Kessler, J. A., & Espinosa, H. D. (2015). Isolating single cells in a neurosphere assay using inertial microfluidics. Lab on a chip, 15(24), 4591–4597.

  • In this work, researchers used inertial microfluidics to separate the single cells and clusters in a population of chemically dissociated neurospheres. In contrast to previous microfluidic sorting technologies which operated at high flow rates, they implemented the spiral microfluidic channel in a novel focusing regime that occurs at lower flow rates. The 38 µm polyethylene microbead powder (Cospheric, SD~3 µm) was first dispersed in 0.1% (w/v) suspension of Tween 80 (Cospheric) surfactant for preventing particle aggregation. A 7.7 µm microbead suspension (Spherotech, SD~0.5 µm) provided at 1% (w/v) was diluted to 0.1% (w/v) using de-ionized water. Equal volumes of the two suspensions were mixed and then pumped through the device at different flow rates using a syringe pump (New Era Pump Systems). The focusing positions were observed near the outlets using a dark field microscope (Olympus-IX71).

Katija, K., Choy, C. A., Sherlock, R. E., Sherman, A. D., & Robison, B. H. (2017). From the surface to the seafloor: How giant larvaceans transport microplastics into the deep sea. Science advances, 3(8), e1700715.

  • Larvaceans are abundant components of global zooplankton assemblages, regularly build mucus “houses” to filter particulate matter from the surrounding water, and later abandon these structures when clogged. By conducting in situ feeding experiments with remotely operated vehicles, the scientists show that giant larvaceans are able to filter a range of microplastic particles from the water column, ingest, and then package microplastics into their fecal pellets.Polyethylene microspheres, or microplastic particles(Cospheric LLC), were selected based on particle density (closely matching the density of seawater or 1.027 g/cm3) and size range, while minimizing overlap of coloration to distinguish between particle size classes during feeding experiments. Given these constraints, red, orange, yellow, and green microplastic particles were selected that ranged in size from 10 to 600 µm in diameter. All particles but the largest size class (red; 500 to 600 µm in diameter) had fluorescent surface coatings to enhance visibility for observations during experiments. Microplastics were prepared using a protocol that uses Tween 80 biocompatible surfactant to ensure separation of particles once in solution ( To minimize any adverse behavioral responses to the surfactant, the Tween solution was replaced with seawater at the end of the protocol, which did not have any visible effect on particle separation.

Durmus, N. G., Tekin, H. C., Guven, S., Sridhar, K., Arslan Yildiz, A., Calibasi, G., Ghiran, I., Davis, R. W., Steinmetz, L. M., & Demirci, U. (2015). Magnetic levitation of single cells. Proceedings of the National Academy of Sciences of the United States of America, 112(28), E3661–E3668.

  • Cells consist of micro- and nanoscale components and materials that contribute to their fundamental magnetic and density signatures. Previous studies have claimed that magnetic levitation can only be used to measure density signatures of nonliving materials. Here, the researchers demonstrate that both eukaryotic and prokaryotic cells can be levitated and that each cell has a unique levitation profile. Furthermore, proposed levitation platform uniquely enables ultrasensitive density measurements, imaging, and profiling of cells in real-time at single-cell resolution. Fluorescent polyethylene beads (Cospheric LLC) (10–100 µm in size) with different densities (1.025 ± 0.007 g·mL-1, 1.030 ± 0.007 g·mL-1, 1.044 ± 0.007 g·mL-1, 1.064± 0.007 g·mL-1, and 1.089 ± 0.007 g·mL-1) were suspended in FBS with various magnetic susceptibilities (10 mM, 30 mM, and 50 mM paramagnetic Gd solution). Then, the beads were loaded into the microcapillaries and levitated. Fitting the resulting plot of density (grams per milliliter) versus levitation height (micrometers) to a linear curve provided a standard function to measure densities. Based on these curves, resolution and dynamic range of density measurements were calculated for different Gd concentrations.

Huszka, G., & Gijs, M. (2018). Turning a normal microscope into a super-resolution instrument using a scanning microlens array. Scientific reports, 8(1), 601.

  • Scientists report dielectric microsphere array-based optical super-resolution microscopy. A dielectric microsphere that is placed on a sample is known to generate a virtual image with resolution better than the optical diffraction limit. Cospheric's 38–45µm diameter BTG microspheres.

Klohonatz, K. M., Nulton, L. C., Hess, A. M., Bouma, G. J., & Bruemmer, J. E. (2019). The role of embryo contact and focal adhesions during maternal recognition of pregnancy. PloS one, 14(3), e0213322.

  • In a non-pregnant mare on day 14 post-ovulation (PO), prostaglandin F2a (PGF) is secreted by the endometrium causing regression of the corpus luteum. Prior to day 14, MRP must occur in order to attenuate secretion of PGF. The embryo is mobile throughout the uterus due to uterine contractions from day of entry to day 14. It is unknown what signaling is occurring. Literature stated that infusing oil or placing a glass marble into the equine uterus prolongs luteal lifespan and that in non-pregnant mares, serum exosomes contain miRNA that are targeting the focal adhesion (FA) pathway. The hypothesis of this study is embryo contact with endometrium causes a change in abundance of focal adhesion molecules (FA) in the endometrium leading to decrease in PGF secretion. Mares (n = 3/day) were utilized in a cross-over design with each mare serving as a pregnant and non-pregnant (non-mated) control on days 9 and 11 PO. Biopsy samples were cultured in one of four conditions: (1) direct contact with an embryo from the corresponding day (EE), (2) direct contact with plastic beads (utilized routinely to teach embryo flushing and transfer) (EB) (Cospheric, Product Number: UVPMS-BR-1-5, Santa Barbara, CA), (3) direct contact with peanut oil (EO) and (4) endometrial biopsy alone (control)(E-).

Tauro, F., Mocio, G., Rapiti, E., Grimaldi, S., & Porfiri, M. (2012). Assessment of fluorescent particles for surface flow analysis. Sensors (Basel, Switzerland), 12(11), 15827–15840.

  • The system is based on the detection of buoyant fluorescent microspheres through a low-cost apparatus, which incorporates light sources to elicit fluorescence response and a digital camera to identify the particles' transit. Experiments are conducted using green fluorescent particles and further tests are executed to evaluate the system performance for red and orange particles varying in emission wavelength, degree of biocompatibility, and cost. In this paper, the performance of the novel measurement system is assessed by conducting experiments with three classes of fluorescent particles. Specifically, off-the-shelf 710–1,180 µm yellow-green fluorescent spheres are purchased from Cospheric LLC. The beads are white under daylight and emit yellow-green light (561 nm wavelength) if excited by a UV light source (365 nm wavelength). Red-fluorescent beads are also purchased from Cospheric LLC. Such particles are available in smaller sizes, that is, 250–300 µm and their nominal dry density is 0.995 g/cm3. They are spherical in shape and present a high emission peak at 605 nm if excited by white light, that is, by a light source emitting from 460 to 650 nm.

Tauro, F., Aureli, M., Porfiri, M., & Grimaldi, S. (2010). Characterization of buoyant fluorescent particles for field observations of water flows. Sensors (Basel, Switzerland), 10(12), 11512–11529.

  • In this paper, the feasibility of off-the-shelf buoyant fluorescent microspheres as particle tracers in turbid water flows is investigated. Microspheres’ fluorescence intensity is experimentally measured and detected in placid aqueous suspensions of increasing concentrations of clay to simulate typical conditions occurring in natural drainage networks. The particles are purchased from Cospheric LLC. The beads are approximately spherical and their diameter is in the range of 0.710–0.850 mm. The spheres are white under daylight and emit yellow-green light (561 nm wavelength) if excited by a UV light source (365 nm wavelength). The particle material is polyethylene and the fluorophore is embedded in the polymer matrix which allows for a long luminescence life-time. The particles nominal dry density is 0.99 g/cm3.

Hu, Z., & Ripple, D. C. (2014). The Use of Index-Matched Beads in Optical Particle Counters. Journal of research of the National Institute of Standards and Technology, 119, 674–682.

  • In this paper, we demonstrate the use of 2-pyridinemethanol (2P) aqueous solutions as a refractive index matching liquid. The high refractive index and low viscosity of 2P-water mixtures enables refractive index matching of beads that cannot be index matched with glycerol-water or sucrose-water solutions, such as silica beads that have the refractive index of bulk fused silica or of polymethylmethacrylate beads. PMMA beads of a nominal size range 63 µm to 75 µm were obtained from Cospheric (Santa Barbara, CA).

Dommersnes, P., Rozynek, Z., Mikkelsen, A., Castberg, R., Kjerstad, K., Hersvik, K., & Otto Fossum, J. (2013). Active structuring of colloidal armour on liquid drops. Nature communications, 4, 2066.

  • Adsorption and assembly of colloidal particles at the surface of liquid droplets are at the base of particle-stabilized emulsions and templating. Here we report that electrohydrodynamic and electro-rheological effects in leaky-dielectric liquid drops can be used to structure and dynamically control colloidal particle assemblies at drop surfaces, including electric-field-assisted convective assembly of jammed colloidal ‘ribbons’, electro-rheological colloidal chains confined to a two-dimensional surface and spinning colloidal domains on that surface. Silicone drops with colloidal beads are also studied: Fluorescent PE beads (UVPMS- BY2 45–53µm) and conductive silver-coated glass beads (SLGMS- AG 45–53µm) were purchased from Cospheric LLC.

Wisdom, K. M., Watson, J. A., Qu, X., Liu, F., Watson, G. S., & Chen, C. H. (2013). Self-cleaning of superhydrophobic surfaces by self-propelled jumping condensate. Proceedings of the National Academy of Sciences of the United States of America, 110(20), 7992–7997.

  • Here, we demonstrate a unique self-cleaning mechanism whereby the contaminated superhydrophobic surface is exposed to condensing water vapor, and the contaminants are autonomously removed by the self-propelled jumping motion of the resulting liquid condensate, which partially covers or fully encloses the contaminating particles. The jumping motion off the superhydrophobic surface is powered by the surface energy released upon coalescence of the condensed water phase around the contaminants. For the study of particle removal processes, large particles were used: silver-coated solid glass spheres with a diameter range of 43–62 µm (Cospheric SLGMS-AG) and PMMA spheres with a diameter range of 90–106 µm (Cospheric PMPMS).

van de Wouw, J., Sorop, O., van Drie, R., van Duin, R., Nguyen, I., Joles, J. A., Verhaar, M. C., Merkus, D., & Duncker, D. J. (2020). Perturbations in myocardial perfusion and oxygen balance in swine with multiple risk factors: a novel model of ischemia and no obstructive coronary artery disease. Basic research in cardiology, 115(2), 21.

  • Comorbidities of ischemic heart disease, including diabetes mellitus (DM), hypercholesterolemia (HC) and chronic kidney disease (CKD), are associated with coronary microvascular dysfunction (CMD). Increasing evidence suggests that CMD may contribute to myocardial ‘Ischemia and No Obstructive Coronary Artery disease’ (INOCA). In the present study, we tested the hypothesis that CMD results in perturbations in myocardial perfusion and oxygen delivery using a novel swine model with multiple comorbidities. The renal arteries were catheterized under fluoroscopy guidance (right renal artery and selective catheterization of the artery perfusing the left lower renal pole) with a Swan–Ganz catheter, inserted through a 9F sheath in the right common carotid artery. Following inflation of the balloon to prevent back-flow into the aorta, 75 mg of polyethylene microspheres with a diameter of 38–42 µm (Cospheric, Santa Barbara, CA, USA) were infused into each kidney via the distal port of the catheter.

Norouzi N, Bhakta HC, Grover WH. Sorting cells by their density. PLoS One. 2017;12(7):e0180520. Published 2017 Jul 19. doi:10.1371/journal.pone.0180520

  • Sorting cells by their type is an important capability in biological research and medical diagnostics. However, most cell sorting techniques rely on labels or tags, which may have limited availability and specificity. Sorting different cell types by their different physical properties is an attractive alternative to labels because all cells intrinsically have these physical properties. But some physical properties, like cell size, vary significantly from cell to cell within a cell type; this makes it difficult to identify and sort cells based on their sizes alone. In this work we continuously sort different cells types by their density, a physical property with much lower cell-to-cell variation within a cell type (and therefore greater potential to discriminate different cell types) than other physical properties. For the experiment, polyethylene microbeads (40 µm diameter, 1.025 g/mL density) and polystyrene microbeads (6 µm diameter, 1.05 g/mL density) were obtained from Cospheric (Santa Barbara, CA).

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