Thermo Scientific™ Blocker™ BSA

Catalog No.	Quantity	Chemical Name or Material
PI37525	200 mL	PBS
FER37525X3	3 x 200 mL	PBS
PI37520	125 mL	TBS

Catalog No. PI37525 Supplier Thermo Scientific™ Supplier No. 37525

Description

Blocker BSA is a purified 10% solution of bovine serum albumin for blocking in western blotting, ELISA, IHC, and nucleic acid detection methods.

Blocker BSA is a 10% (w/v) solution of high-quality BSA that is useful for saturating excess protein-binding sites on membranes and microplates in immunoassays. It is most frequently diluted 10-fold (to 1% BSA) in 1X PBS or 1X TBS for initial testing. Blocker BSA is usually more effective than nonfat milk for biotin-avidin systems because it contains a single purified protein that is devoid of endogenous biotin.

Specifications

• Chemical Name or Material: PBS
• Description: Blocker BSA in PBS (10X)
• Concentration: 10X
• For Use With (Application): Western Blot
• Physical Form: Liquid
• Product Line: Blocker
• Quantity: 200 mL
• Formulation: 10% BSA

Frequently Asked Questions (FAQs)

How can I reduce background bands in my Western blot?

Optimize the concentration of primary and secondary antibodies. In some cases, increasing the concentration of blocking agent (BSA or non-fat dry milk) or usiing an alternative blocking solution such as Starting Block or SuperBlock may reduce background signal. After incubation with the primary antibody, wash at least 2 times with TBST (include 0.5 M NaCl in one or more of the wash steps). Avoid Nonidet P40 or Triton X-100 in buffers because protein detection is decreased when these detergents are used.

I would like to dilute an HRP-conjugated primary antibody in Blocker BSA (10X) in PBS (Cat. No. 37525). How can I ensure that the BSA does not contain sodium azide?

Our liquid blocker formulations, including Blocker BSA (10X) in PBS, are free of sodium azide and mercury compounds, such as thimerosal. They only contain Kathon CG/ICP at 600 ppm, as stabilizer. Using this BSA with HRP-coupled antibodies is absolutely common.

Is the Blocker BSA (10X) in PBS (Cat. No. 37525) suitable for cell culture usage?

This has not been tested. Instead, we would recommend using AlbuMAX I Lipid-Rich BSA (Cat. No. 11020021 or 11020039).

I used a neuron-specific antibody to label my neurons. How can I reduce non-specific antibody binding?

A blocking step should be performed to reduce fluorescence due to non-specific antibody binding. A common blocking step is the addition of a 2-5% solution of bovine serum albumin (fraction V defatted BSA). Another approach employs the addition of a 5-10% solution of serum from the species in which the secondary antibodies were raised. For example, when using goat anti-mouse IgG secondary antibodies, samples may be effectively blocked with 5-10% normal goat serum. To further reduce background fluorescence, the Image-iT FX Signal Enhancer can be included as a pre-blocking step to decrease non-specific labeling due to charge interactions between the dyes on the conjugates and the cellular constituents.
If you are using a secondary antibody make sure that the species of the antibody is not the same as the species of the sample. For example do not use an anti-mouse secondary antibody on mouse tissue.
Titrate the antibody to the lowest concentration you can use and still get adequate signal.
Try using a fluorescently tagged primary antibody because it should give reduced background but be aware this can reduce signal intensity.

After labeling with my antibody, I am seeing non-specific background binding in my cells or tissue. What could be the cause?

There can be many causes, including insufficient blocking, too high a concentration of the primary or secondary antibody, or degraded primary or secondary antibody. A “no-primary antibody” control can help determine if the secondary antibody is at fault. Otherwise, we recommend trying more stringent blocking or lower concentrations of primary and secondary antibodies.

What concentration of my antibody should I use for cell analysis?

An optimal concentration may be between 1-10 µg/mL for cell and tissue labeling for microscopy, or 0.2-5 µg/mL for flow cytometry. A range of concentrations should be tested to determine what is optimal.

I know I need to block my samples against non-specific protein binding of my antibodies, but which blocker should I use?

For blocking cells or tissues you may use 2-5% bovine serum albumin (fraction V, defatted BSA) or 5-10% normal serum of the species matching the host species of the secondary antibody. Other options include a mixture of BSA and serum or other purified proteins. We offer a ready-made blocking solution, BlockAid Blocking Solution (Cat. No. B10710), which is not species-specific. For cell or tissue samples, avoid the use of non-fat dry milk as a blocking agent as it contains a high level of phosphoproteins, histones, and biotin.