ELISA Blocking Reagents / Blocking Buffers

Surmodics™ IVD has a wide selection of reliable, ready-to-use ELISA blocking reagents, also referred to as blocking buffers, for assay manufacturing companies and laboratory professionals looking to build sensitive, reproducible immunoassays. We offer several blocking reagents/blocking buffers for immunoassays, including point-of-care applications, ELISA’s and more. Each of Surmodics IVD’s ELISA blocking reagents/blocking buffers offer assay developers the gold standard in product performance and quality. Our ISO 13485:2016 and 9001:2015 certifications allow us to provide a level of unmatched consistency and quality.

Our ELISA blocking reagents/blocking buffers include a line of dried protein stabilizers and blockers, sample or assay diluents and western blot blocking buffers. Our ELISA blocking reagents/blocking buffers are designed to increase the sensitivity and stability of immunoassays, including ELISA applications while blocking interferences that impact the accuracy and reliability of immunoassays. Furthermore, our ELISA blocking reagents help to reduce cross-reactivity and interferences from Human Anti-Mouse Antibodies (HAMA) and Rheumatoid Factor (RF) as well as non-specific binding.

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Characteristics of Ideal ELISA Blocking Reagents

A common question assay developers may ask is what does a blocking buffer do for the assay? As an assay developer, it is critical to find an ELISA blocking reagent/blocking buffer that offers optimal blocking for your specific immunoassay needs.

In your search for ELISA blocking reagents/blocking buffers, it can be helpful to understand the key characteristics that ELISA blocking reagents/buffers offer.

In your search for ELISA blocking reagents, it can be helpful to understand the key characteristics that ELISA blocking reagents offer.

1. Reduces the risk for non-specific binding from the sample matrix and other assay components.
2. Offers extended shelf life of dried proteins on various surfaces, including polystyrene plates, latex beads, magnetics particles and nitrocellulose membranes.
3. Provides increased signal-to-noise ratios across the assay range.
4. Prevents denaturation and act as a stabilizer for solid phase assay reactants.
5. Reduces cross-reactivity with any other components of the assay.
6. Should not have any kind of activity that is enzymatic, since this could possibly lead to the degradation of the reactants or interfere with the generation of a signal from the substrate.
7. Offers consistent performance across multiple assay formats and should also ensure lot-to-lot consistency.

The main characteristic that determines if a blocking buffer is effective is that it should reduce the background signal and improve the ratio of signal-to-noise, thus improving the overall sensitivity of an assay. Surmodics IVD’s ELISA blocking reagents/blocking buffers help to increase the signal-to-noise ratios and in turn, enhance the accuracy and reliability of immunoassays.

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Specific Families of Blocking Reagents / Blocking Buffers

Dried Protein Stabilizers & Blockers:

Surmodics IVD’s StabilCoat™, StabilGuard™ and StabilBlock™ dried protein stabilizers and blockers preserve the conformation and activity of dried proteins coated on a wide range of surfaces, keeping antibodies and antigens at peak performance for long durations. At the same time, the blocking mechanisms in these reagents reduce non-specific binding of interfering proteins to maximize assay sensitivity. These ELISA blocking reagents/blocking buffers are the industry gold standard for stability and blocking efficacy. The result is immediate improvement of assay performance in a one-step process for streamlined manufacturing.

Assay developers need numerous blocking mechanisms while selecting the antibody titration during assay optimization. Our dried protein stabilizers and blockers provide alternative blocking mechanisms to achieve the best signal-to-noise ratios for each assay. With the introduction of StabilBlock, Surmodics IVD now offers the best available reagent for reducing non-specific binding to boost immunoassay signal-to-noise ratios.

We are often asked how our ELISA blocking reagents/blocking buffers differ from each other. Each of these reagents offer a stabilizing capability as well as a blocking mechanism. While all three do an excellent job of stabilizing an antigen or antibody, they differ in their blocking mechanism and strength, offering assay developers a variety of options for their specific blocking needs. Specifically, StabilCoat and StabilBlock both contain bovine protein, whereas StabilGuard is completely protein free.

Assay developers may ask what is a BSA blocking buffer? A BSA blocking buffer is simply a blocker that contains a bovine serum albumin. BSA blockers are commonly used in assay development.

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Assay/Sample Diluents:

Surmodics IVD’s ELISA blocking reagents/blocking buffers also include sample or assay diluents that help to reduce matrix interferences in the assay. Surmodics Assay Diluent and MatrixGuard™ Diluent are the gold standard for reducing false positives in your assay. Both formulations provide two options to use when different methods are needed to block matrix interferences, while maintaining the clinical utility of the assay.

For IVD kit manufacturers requiring a strong, consistent blocking diluent across a variety of assays, MatrixGuard Diluent provides unsurpassed blocking whereby matrix interferences are effectively blocked while the intended assay signal is maintained. Unlike other diluents that either are marginally effective at blocking matrix interferences or alternatively block out true assay signal, MatrixGuard Diluent achieves the goal of maximum blockade of matrix interferences while simultaneously allowing signal to be maintained.

Western Blot Blocking Buffers:

Surmodics IVD’s ELISA blocking reagents/blocking buffers also include sample or assay diluents that help to reduce matrix interferences in the assay. Surmodics Assay Diluent and MatrixGuard™ Diluent are the gold standard for reducing false positives in your assay. Both formulations provide two options to use when different methods are needed to block matrix interferences, while maintaining the clinical utility of the assay.

Western blotting, also known as immunoblotting, is a method used to detect a target protein. Western blotting combines the protein separation capabilities of PAGE (polyacrylamide gel electrophoresis) and immunochemistry to detect these target proteins from a complex matrix such as cell or tissue lysate. Membranes used in western blotting are porous and should be blocked to avoid nonspecific binding and background.

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What is an ELISA Wash Buffer?

Although not technically categorized as a blocking reagent/blocking buffer, ELISA wash buffers play an important role in assay development. ELISA wash buffers are often used in a variety of ELISA applications. ELISA wash buffers are commonly used to rinse microtiter plates during the coating process and between reagent addition steps during an ELISA assay.

ELISA wash buffers help eliminate any excess material found from the wells of a microtiter plate. This is done without disrupting the intended antigen – antibody binding reaction. With the proper buffering environment, unbound assay components can be washed away without suppressing antibody binding interactions. As a result, non-specific binding is reduced.

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Choosing the Right Blocking Reagent

There is a wide variety of blocking buffer solutions that can be used for a wide range of applications and each has their own advantages and disadvantages. Obtaining information on which blocking buffer is best to be used in various applications is a critical component in accurate testing results. When selecting a blocking buffer, the most important characteristic to look for is a blocking buffer that will yield the optimal signal-to-noise ratio. It is also important to choose a blocking buffer that does not contain any substances that might interfere with the assay.

Here is more information on how to obtain optimal results from blocking experiments:

• Use various blocking reagents/blocking buffers for experiments and monitor the signal strength and background in each.
• Select a blocking buffer that will yield the highest signal-to-noise ratio
• Make sure that there are not any substances that are within the blocking buffer that might interfere with the assay’s performance.

Methods for Blocking:

Another common question assay developers ask is how to block an ELISA plate?

Here at Surmodics, we offer specific protocols for each of our products, including our blocking reagents/blocking buffers. You can visit the specific product pages for our blockers and view the product inserts under the documents section to find our product specific protocols.

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