FAQ: Stabilization Products

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General Questions

What are some of the advantages of using SurModics Stabilization Products?

  1. They increase the shelf life of your diagnostic kit;
  2. They decrease the variability often associated with shipping and storage conditions;
  3. They reduce error by eliminating the conjugate dilution step;
  4. They increase convenience, as they are ready-to-use;
  5. The preservatives present in some of the products do not contain mercury or azide, eliminating the use and disposal restrictions associated with these types of preservatives;
  6. They have routinely shown unsurpassed stability and efficacy compared to standard reagents and competitor products currently on the market;
  7. Using SurModics Stabilization Products in place of your own in-house reagents can reduce your costs and save you time.

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What ingredients do the protein stabilizers contain?

The product formulations are trade secrets; therefore, we cannot disclose any of the proprietary ingredients. Please refer to the generic description of each product.

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How can I get a product approved without knowing what is in it?

  • All of our products are manufactured according to QSR guidelines, under ISO 9001 (PDF) and 13485 (PDF);
  • Certificates of Conformance are provided to confirm that the products meet all specifications prior to being released for sale;
  • Material Safety Data Sheets (MSDS) are available for all of the products;
  • All of the products are proven, critical components of several commercially available diagnostic devices.

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Are there any test kits approved through the FDA that incorporate SurModics stabilizers as components?

Yes!

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Will any of the Stabilization Products interfere with my assays?

Generally no, but always test first to ensure compatibility with your assay. If StabilZyme HRP Conjugate Stabilizer shows interference in competitive assays, we recommend trying StabilZyme SELECT or StabilZyme NOBLE (BSA-Free) Stabilizers.

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Is it okay that samples are shipped at room temperature, even though storage recommendations state "Store refrigerated or at room temperature"?

None of our stabilization products require refrigeration during transit, and are shipped under ambient conditions. The shelf life studies at room temperature support this. In addition, the products have historically been shipped under these conditions with no adverse effects in product shelf-life, quality, or performance.

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Troubleshooting Assays

Are there specific recommendations for using the Stabilization Products in different assay formats?

Yes. We recommend the following:

  • For membrane assays, dilute the Stabilization Products up to a 1:10 dilution.
  • For strip tests, dilute the Stabilization Products 1:1 (50%).
  • For Western Blots, use the Stabilization Products as purchased (100% concentration - do not dilute).

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Bovine Serum Albumin (BSA)

What testing does SurModics perform on the BSA used in some of the Stabilization Products?

SurModics tests for the presence of alkaline phosphatase and peroxidase in BSA used in some of the Stabilization Products.

How does SurModics verify the origin of any BSA that may be used in the Stabilization Products?

StabilCoat Immunoassay Stabilizer, StabilZyme HRP and AP Conjugate Stabilizers, and StabilZyme SELECT Stabilizer contain less than 10 grams per liter of a bovine-derived serum protein. Our suppliers of this component certify that the bovine plasma from which it was purified was collected entirely from domestic animals in abattoirs regulated by the United States Department of Agriculture. All abattoirs are located in the United States. Furthermore, the animals from which the plasma was derived received ante-mortem and post-mortem inspection at the time of slaughter and appeared to be free from infectious and contagious diseases and injurious parasites. The United States Department of Agriculture considers the United States to be free from Bovine Spongiform Encephalopathy (BSE). These products do not contain and are not derived from any Specified Risk Materials as defined as the following: the skull, including the brain, eyes, tonsils and spinal cord of: bovine animals aged over 12 months, or ovine and caprine animals which are aged over 12 months or have permanent incisor tooth erupted through the gum.

Can I get a copy of the Certificate of Origin for the BSA used in some of the Stabilization Products?

Yes. Get your copy of our BSA Certificate of Origin (PDF).

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Diluents and Dilutions

What can be used to dilute SurModics Stabilization Products?

We recommend using the protein stabilizers undiluted for maximum stabilization. However, in cases where you feel it may be necessary to dilute the products (i.e., in membrane assay or strip tests) please use the following diluents:

  • StabilCoat & StabilCoat Plus can be diluted in deionized water or PBS.
  • StabilGuard & StabilGuard Choice can be diluted in deionized water or PBS.
  • StabilZyme HRP may be diluted in deionized water.
  • StabilZyme AP may be diluted in deionized water or 10mM MES buffer, pH 6.0.
  • StabilZyme SELECT may be diluted in deionized water.
  • StabilZyme NOBLE may be diluted in deionized water.

NOTE: If a phosphate buffer is used, we recommend a final concentration of no more than 5 mM buffer to avoid the possibility of initiating precipitation.

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Dyes

Can I add phenol red to any of the Stabilization Products?

We do not recommend using phenol red with the StabilZyme stabilizers as it may cause interference.

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Can I add food coloring to any of the Stabilization Products?

Yes, as long as it is removed before the detection step.

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Preservatives

Is there a preservative in the Stabilization Products?

No preservatives are added to StabilCoat & 5X StabilCoat Stabilizers or to StabilGuard Stabilizer. If you would like to add a preservative to either of these products, we recommend using ProClin™ at the manufacturer's recommended use concentration.

A mixture of bromonitrodioxane and methylistothiazolone, is added to the following Stabilization Products:

StabilCoat Plus Microarray Stabilizer
StabilGuard Choice Microarray Stabilizer (BSA-Free)
StabilZyme AP Conjugate Stabilizer
StabilZyme HRP Conjugate Stabilizer
StabilZyme SELECT Stabilizer
StabilZyme NOBLE Stabilizer (BSA-Free)

The preservative is a mixture of bromonitrodioxane and methylisothiazolone.

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Do you have any data showing the efficacy of preservative used in the StabilZyme stabilizers, StabilCoat Plus or StabilGuard Choice stabilizers?

An antimicrobial is used in the formulation of SurModics stabilization products to preserve their biological integrity. We do not make any further claims for antimicrobial efficacy once the product is in use. During development of the products, Antimicrobial Preservative Effectiveness was performed. A summary of the results may be requested from Customer Service.

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Can Thimerosal be added to the Stabilization Products?

Yes. You may use a concentration of 0.01-0.05%.

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Can Sodium Azide be added to the Stabilization Products?

Sodium azide interferes with horseradish peroxidase (HRP). However, since the preservative is most likely washed out after blocking or during the assay, this should not be a concern. Of course, this should be tested in your system to ensure desired results.

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Quality Control and Assurance

How does SurModics ensure lot-to-lot consistency with the production of its Stabilization Products?

All SurModics Stabilization Products are manufactured per ISO13485 (PDF)standards under stringent controls to ensure lot-to-lot consistency and complete lot traceability. The raw material components of each lot are proprietary; however, be assured that each component is fully qualified before release to the manufacturing floor. All manufacturing materials are quarantined until required testing and inspection have been performed and acceptance criteria have been met. For each lot, final quality control testing confirms that the lot meets pre-defined product specifications for proprietary components, physical characteristics, and performance.

Tell me more about the ISO 9001 (PDF) andISO 13485 (PDF) Certifications.

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How does SurModics verify the origin of any bovine serum albumin (BSA) used in the Stabilization Products?

StabilCoat Immunoassay Stabilizer and the StabilZyme AP and HRP Conjugate Stabilizers, and StabilZyme SELECT Stabilizer contain less than 10 grams per liter of a bovine-derived serum protein. Our suppliers of this component certify that the bovine plasma from which it was purified was collected entirely from domestic animals in abattoirs regulated by the United States Department of Agriculture. All abattoirs are located in the United States. Furthermore, the animals from which the plasma was derived received ante-mortem and post-mortem inspection at the time of slaughter and appeared to be free from infectious and contagious diseases and injurious parasites. The United States Department of Agriculture considers the United States to be free from Bovine Spongiform Encephalopathy (BSE). These products do not contain and are not derived from any Specified Risk Materials as defined as the following: the skull, including the brain, eyes, tonsils and spinal cord of: bovine animals aged over 12 months, or ovine and caprine animals which are aged over 12 months or have permanent incisor tooth erupted through the gum.

Learn more about our BSA Certificate of Origin (PDF).

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Storage and Shelf Life

What are the shelf life and storage recommendations for the Stabilization Products?

The optimal storage temperature for the Stabilization Products is 2-8°C; however, storage at room temperature will not affect product performance.

Please note that Stabilization Products are shipped to customers at ambient temperature. However, extensive stability studies show that prolonged storage at ambient temperature will not affect the product quality or efficacy.

The shelf life of each product is as follows:

StabilCoat Immunoassay Stabilizer

36 months

5X StabilCoat Immunoassay Stabilizer

24 months

StabilCoat Plus Microarray Stabilizer

24 months

StabilGuard Biomolecule Stabilizer (BSA-Free)

36 months

StabilGuard Choice Microarray Stabilizer (BSA-Free)

36 months

StabilZyme AP Conjugate Stabilizer

30 months

StabilZyme HRP Conjugate Stabilizer

30 months

StabilZyme SELECT Stabilizer

30 months

StabilZyme NOBLE Stabilizer (BSA-Free)

30 months

Learn more about the properties of all SurModics Stabilization Products (PDF).

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StabilCoat and StabilGuard Stabilizers

What is the difference between StabilCoat and StabilGuard Stabilizers?

Both products maintain the conformation and biological activity of dried protein components in immunoassays. StabilCoat has a protein component, but StabilGuard contains no animal-source protein, eliminating the possibility of test interference or cross reactivity.

Note: StabilGuard is a very effective blocker and stabilizer. When working with adsorbed proteins, if allowed to stay in the well too long, StabilGuard can begin to desorb the protein coating. Therefore, customers should take into consideration how long they block. Diluting the StabilGuard 1:2 or even 1:4 is an option (do not dilute any more than 1:4).

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How should I handle my plates after stabilizing with StabilCoat or StabilGuard Stabilizer?

Dry plates quickly to ensure optimum stabilization. We recommend drying at 20% humidity and using moisture-proof packaging.

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What is the difference between StabilCoat and StabilCoat Plus Stabilizers?

StabilCoat Immunoassay and StabilGuard Biomolecule Stabilizers maintain the activity of antibodies, enzymes, and antigens in the dry state, e.g., used in ELISAs. StabilCoat Plus and StabilGuard Choice Stabilizers provide optimum performance for both microsphere and protein microarray applications. In addition, both StabilCoat Plus and StabilGuard Choice contain an azide- and mercury-free preservative that is a mixture of bromonitrodioxane and methylisothiazolone.

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What is the difference between StabilGuard and StabilGuard Choice Stabilizers?

StabilGuard and StabilGuard Choice do not have bovine protein in their formulation. If you are currently using StabilCoat Immunoassay Stabilizer or StabilGuard Biomolecule Stabilizer for dry stabilization, there is no need to change to StabilCoat Plus or StabilGuard Choice Stabilizers.

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What is the shelf life of the StabilCoat and StabilGuard Stabilizers when stored at 4°C?

StabilCoat Stabilizer

36 months

5X StabilCoat & StabilCoat Plus

24 months

StabilGuard & StabilGuard Choice

36 months

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What is the shelf life of a component (e.g., microtiter plate) coated with StabilCoat or StabilGuard Stabilizer?

Real-time studies indicate that a shelf life of 30 months at room temperature is achievable. Studies were based on a goat anti-rabbit IgG antibody.

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What can be used to dilute StabilCoat and StabilGuard Stabilizers?

We recommend using the stabilizers undiluted for maximum stabilization. However, in cases where you feel it may be necessary to dilute the products, StabilCoat and StabilGuard Stabilizers can be diluted in deionized water or PBS.

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Will StabilCoat Stabilizer cause interference?

StabilCoat absorbs at 340 nm at use concentration, the same wavelength at which alcohol dehydrogenase absorbs. Therefore, dilution of the StabilCoat (1:1) in deionized water or PBS may resolve this problem.

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What does it mean if StabilCoat or StabilGuard Stabilizer is turbid?

Turbidity in StabilCoat or StabilGuard is usually the result of contamination since the products have no preservative. If you are not aseptically aliquoting, we recommend you add a preservative, e.g., Proclin.

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Drying Antibodies and Proteins

Can the drying method cause variability in my assay?

High background can be caused by the drying technique: It is very important that the antibodies do not dry to the surface of the substrate before StabilCoat or StabilGuard Stabilizer is added as it will cause a loss of activity. After incubation and aspiration of StabilCoat or StabilGuard, the antibodies should be completely dried. The faster the drying time, the better. We recommend using a humidity-controlled (less than 15% humidity) incubator for 4 to 24 hours, or drying the antibodies in a dry vacuum oven for 4 hours at 30°C. If an incubator or vacuum oven is not available, the antibodies can be dried in a sealed, desiccated container, such as an airtight plastic container, jar, or plastic bag containing calcium sulfate or silica gel desiccant for 2 to 24 hours. It is also important to store the dried proteins in airtight containers with desiccant to prevent moisture from getting into the product. Anything that reduces the drying time can greatly improve the stability and activity of the antigen. Studies were conducted that compared drying times and humidity levels and results demonstrated these to be the two most critical factors in maintaining antibody stability. Extended drying times at higher humidity levels can result in a significant loss of coated antibody activity.

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What percentage of humidity is optimal for drying microtiter plates?

We recommend drying at 20% humidity or less for the best stability. Drying at room temperature is acceptable, although this may increase drying time and result in a slight loss of activity unless the humidity is below 20%. The faster the plates are dried, the better the retained activity will be. We recommend using an airtight container filled with desiccant for plate drying. Once dried, the plates should be sealed and stored in an air tight container with desiccant.

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Can StabilZyme products be used for dried assay components?

No. All of the StabilZyme products are designed to stabilize biologically active components in solution.

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Can you recommend a stabilizer for lyophilized material?

We recommend using the StabilCoat Immunoassay Stabilizer for this purpose. The customer should NOT use the StabilGuard Biomolecule Stabilizerósome of the components in the product may result in a "gelling" or "gooey" substance when the lyophilized material is thawed.

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Bead and Protein Microarrays

What is the procedure for using StabilCoat Plus or StabilGuard Choice Microarray Stabilizer for storing beads in suspension or dried proteins in arrays?

Read the product information sheets for SurModics Microarray stabilizers:
StabilCoat Plus Microarray Stabilizer (PDF); or
StabilGuard Choice Microarray Stabilizer (PDF)

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Which Microarray Stabilizer do you recommend for magnetic beads?

Magnetic beads can be more challenging to maintain monodispersity. We recommend using StabilCoat Plus Stabilizer. If aggregation is a problem, the addition of 0.05% Tween 20 may help.

Learn more about StabilCoat Plus Microarray Stabilizers.

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Can the Microarray Stabilizers be used to stabilize DNA?

We recommend trying StabilGuard Choice Microarray Stabilizer for stabilizing DNA. You may want to try it at 100% concentration, as well as at a 1:2 dilution (using deionized water).

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StabilZyme Stabilizers

What is the difference between StabilZyme HRP, StabilZyme SELECT and StabilZyme NOBLE stabilizers?

StabilZyme HRP contains components that increase enzyme activity. While this is beneficial in some assays, it causes interference in others, such as competitive assays.

StabilZyme SELECT was developed to provide stabilization comparable to that of StabilZyme HRP, but without increasing enzyme activity that can interfere with the standard curve in competitive assays. StabilZyme SELECT is also recommended for direct or sandwich assays where background is a problem.

StabilZyme NOBLE is a BSA-free alternative to StabilZyme SELECT. It is designed to be used for conjugated proteins, antibody-coated particles, and unmodified proteins in solution.

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What is the shelf life of the StabilZyme Stabilizers when stored at 4°C?

All StabilZyme stabilizers have a shelf life of 30 months when stored at 4°C. Testing was performed on StabilZyme stabilizers with no conjugate added. Products were stored at 37°C and 4°C, and then tested for retained activity after multiple time points up to 30 months. Studies were based on a goat anti-rabbit IgG antibody.

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What shelf life can I expect from a conjugate added to the StabilZyme Stabilizers?

Real-time studies indicate that a shelf life of 24 months at room temperature is achievable.

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What can be used to dilute the StabilZyme Stabilizers?

We recommend using the stabilizers undiluted for maximum stabilization. However, in cases where you feel it may be necessary to dilute the products (e.g., 1:1) please use the following diluents:

  • StabilZyme HRP Stabilizer can be diluted in deionized water.
  • StabilZyme AP Stabilizer can be diluted in deionized water or 10mM MES buffer, pH 6.0.
  • StabilZyme SELECT Stabilizer can be diluted in deionized water or 0.1 M Tris or Glycine buffer.
  • StabilZyme NOBLE Stabilizer can be diluted in deionized water.

NOTE: Phosphate buffers cause precipitation in the StabilZyme products when used at >10% total volume.

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Can StabilZyme HRP stabilize the horseradish peroxidase enzyme by itself?

Yes.

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What should I do if there is an increased signal when I use StabilZyme HRP Stabilizer in my assay?

In some cases, StabilZyme HRP stabilizer increases the signal of the conjugate. If this happens, we recommend trying StabilZyme SELECT, or StabilZyme NOBLE Stabilizer.

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What dilution of antibody conjugate is used for the Quality Control testing for StabilZyme AP Stabilizer?

Our standard ELISA uses a 1:3000 dilution of the conjugate in StabilZyme AP. We recommend diluting your AP conjugate at your normal use concentration first. You may consider trying a small accelerated study to determine that you are getting the stability you need. In our experience, we have found that there can be a large difference in AP conjugate quality and stability depending upon the supplier.

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What dilution of antibody conjugate is used for the Quality Control testing for StabilZyme HRP, SELECT, and NOBLE Stabilizers?

Our standard ELISA uses a 1:10,000 dilution of the conjugate in StabilZyme HRP, SELECT, and NOBLE stabilizers. We recommend you first try diluting the HRP conjugate to your normal use concentration. You may consider a small accelerated study to determine that you are getting the stability you need.

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Can I freeze-dry proteins with StabilZyme stabilizers?

Freeze-drying proteins with the StabilZyme products is not recommended.

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Can the StabilZyme stabilizers be used in serum controls?

Yes. We recommend StabilZyme SELECT and NOBLE stabilizers for stabilizing serum controls.

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Conjugates

What do you recommend for stabilizing HRP-Streptavidin conjugates?

We recommend using StabilZyme HRP Conjugate Stabilizer.

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My AP conjugate is extremely unstable. Can I do anything more to increase efficacy?

Try adding 10% glycerol to the StabilZyme AP Conjugate Stabilizer prior to diluting your conjugate.

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Can you recommend a stabilizer for an ELISA assay that uses both HRP and AP conjugates?

You can try mixing StabilZyme AP Conjugate Stabilizer and StabilZyme SELECT Stabilizer together at a 1:1 ratio.

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Are there any special considerations for using GOLD conjugates with the Stabilization Products?

For gold conjugates in the dry state, StabilCoat should be used. A very small amount of Triton X-100 or other suitable surfactant should be added (start at 0.01% Triton X-100). The quicker you can dry the conjugate, the better.

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Serum Controls

Can any of the Stabilization Products be used to stabilize serum controls?

Yes. Both StabilZyme SELECT and StabilZyme NOBLE Stabilizers have been used successfully by our customers to stabilize serum controls.

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