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FluoSpheres™ Sulfate-Modified Microspheres, 2.0 μm, yellow-green fluorescent (505/515), 2% solids, 2 mL - FAQs

FluoSpheres™ Sulfate-Modified Microspheres, 2.0 μm, yellow-green fluorescent (505/515), 2% solids, 2 mL - FAQs

View additional product information for FluoSpheres™ Sulfate-Modified Microspheres, 0.02–4.0 μm - FAQs (F8853, F8845, F8851, F8852, F8858, F8848, F8859)

18 product FAQs found

I have some FluoSpheres polystyrene microspheres, with 20 nm diameter. They are aggregating a lot. What can I do about it?

The smaller the microspheres, the greater the propensity to aggregate. But the aggregation is not irreversible. Sonicate in a bath sonicator or vortex to disperse, just prior to use. You can also add a small concentration of Tween-20 or Triton X-100 (unless you are using them in a live-cell system).

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

I sonicated my 2.0 µm carboxylate-modified microspheres, as recommended, but saw foaming (bubbles) on top of the solution. Should I be concerned?

Use of a bath sonicator is recommended to help break up any aggregated microspheres. The foaming is from Tween-20, which is in the stock solution to help prevent aggregation. It is normal and expected to see bubbles from this. Do not use a probe sonicator, which would cause damage to the microspheres (as well as much more bubbling).

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

What is the warranty for FluoSpheres microspheres?

The warranty period for FluoSpheres microspheres is 1-year from the date of shipment.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

After washing and centrifugation, there was only a very small pellet left of my microsphere beads and the solution was transparent. Why is this?

Centrifugation is not an effective way to collect smaller microspheres; many particles remain in the solution even if you can visualize a small pellet. For beads less than 1 µm in diameter, we recommend washing by either:

Cross-flow filtration, as these particles have a very high compression modulus and can withstand high g-forces without risk of harm or dialysis with a 500 kDa MWCO
Note: Microspheres greater than 1 µm in diameter can be centrifuged at 1,300 rpm.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

I've had my microspheres for over a year, and I'm wondering if they're still good to use. What are some good ways to check their functionality?

Bacterial contamination is the most common cause of microspheres becoming unusable. Many of our particles are supplied with a low level of sodium azide to prevent bacterial contamination, but sometimes this can still occur. Bacterial contamination is best assessed by plating on appropriate growth medium and checking the plates after 72 hr.

Find additional tips, troubleshooting help, and resources within ourMicrospheres Support Center.

I accidentally froze my microspheres; can I still use them?

Even brief freezing can cause irreversible aggregation and potential distortion of the bead shape. You should not use these microspheres.

Find additional tips, troubleshooting help, and resources within our Microspheres Support Center.

My protein-coated microspheres appear to be non-specifically binding in my experimental system. Do you have a product that can help reduce these non-specific interactions?

Non-specific binding can often be relieved by a blocking solution, but microspheres seem to require a stronger blocking solution than those most commonly commercially available. Hence, we've developed the BlockAid Blocking Solution (Cat. No. B10710). This reagent is a protein-based blocking solution designed for use with FluoSpheres microspheres and TransFluoSpheres microspheres conjugated to biotin, streptavidin, NeutrAvidin biotin-binding protein, or other proteins. The BlockAid Blocking Solution has proven useful for reducing the nonspecific binding of protein-coated or other macromolecule-coated microspheres in a wide variety of flow cytometry, microscopy, and microarray applications.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

What sort of sonication method should I use to disperse microsphere aggregates?

We recommend using a bath sonicator to disperse microsphere aggregates. Do not use a probe sonicator as this will damage the microspheres.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

I sonicated my carboxylate-modified latex microspheres as recommended in the protocol, and I saw foaming in the solution. Should I be concerned?

The foaming is from Tween 20, which is present in the stock solution to help prevent aggregation. It is normal to see bubbles from this reagent.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

Can I centrifuge my fluorescent microspheres?

Microspheres greater than 1 µm in diameter can be centrifuged at 1,300 rpm, but once pelleted they may not disperse readily or not at all. Centrifugation is not an effective way to collect smaller microspheres; for beads less than 1 µm in diameter, we recommend washing by either cross-flow filtration or dialysis with a 500 kDa MWCO.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

Which microspheres should I use to measure regional blood flow? How do I perform these procedures?

We offer a variety of FluoSphere microspheres and kits specifically designed for blood flow determination; if the available colors and/or sizes do not suit your needs, we recommend using beads modified with carboxylate groups for blood flow determination applications. We give some basic usage guidelines in the FluoSpheres Fluorescent Micospheres for Tracer Studies product manual (https://tools.thermofisher.com/content/sfs/manuals/mp13080.pdf). Additionally, the University of Washington Seattle offers the Fluorescent Microsphere Resource Center (FMRC) website (http://fmrc.pulmcc.washington.edu/fmrc.shtml) with detailed applications manuals and references for using fluorescent microspheres to evaluate regional blood flow.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

What microsphere product should I select to perform a point spread function?

Point spread functions will require a subresolution bead, and we have two different subresolution bead products that could be used for this purpose. TetraSpeck Microspheres, 0.1 µm (Cat. No. T7279), are single subresolution microspheres that are simultaneously stained with blue, green, orange, and dark red dyes. The PS-Speck Microscope Point Source Kit (Cat. No. P7220) consists of individually-stained blue, green, orange, and dark red fluorescent microspheres that are approximately 175 nm in diameter.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

What sort of mounting media should I use for fluorescent polystyrene microspheres?

We recommend using a ProLong product or any other aqueous mounting media. You should avoid organic-based mountants such as toluene-based mounting media.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

Are the FluoSpheres microspheres surfactant-free?

The FluoSpheres microspheres may have a trace amount of surfactant. Only IDC Latex beads with diameters greater than 100 nm are actually surfactant-free.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

I want to put my microspheres in something besides water; how will they react in alcohol?

The stability in alcohol or water/alcohol mixtures is dependent on the alcohol chain length. The beads are fairly stable in 40% methanol, but they will dissolve much more readily in long chain alcohols. Prolonged storage of beads in an alcohol containing solution will tend to leach out the dye.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

I noticed that many of your microsphere products have sodium azide present, but I can't have sodium azide in my application. How should I remove sodium azide from the microsphere solution?

We recommend using dialysis with a MWCO of approximately 500,000 to remove the sodium azide from the microsphere-containing buffer.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

How many dye molecules are there in a single fluorescent microsphere?

We do not determine the exact number of dye molecules per microsphere. The number of dye molecules is a function of the diameter of the particle and the properties of the dye.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

How do you label the FluoSpheres microspheres with dye?

The polystyrene microspheres are swelled in a solvent containing a hydrophobic dye specific to the FluoSpheres product. The dye is then able to diffuse into the polystyrene matrix. The beads are then removed from the solvent and dialyzed into an aqueous environment; this reverses the swelling and traps the dye in the polystyrene. Once trapped, the dye is fairly protected from the external environment. The exact protocol and identity of the hydrophobic dyes are proprietary.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.