Types of blocking buffers:

• Normal serum: Normal serum is a common component in blocking buffers. This is because the antibodies present in serum bind to reactive sites, preventing nonspecific binding of secondary antibodies in the assay. Using serum from a source species for the secondary antibody is important. Serum is typically used at concentrations of 1% - 5% (w/v).
• Protein solutions: Apart from serum, blocking buffers often contain proteins such as gelatin, bovine serum albumin (BSA), or nonfat dry milk. When added, either alone or in combination, at final concentrations of 1% - 5% (w/v), they complete for binding to nonspecific sites in the sample.
• Pre-formulated commercial buffers: Ready-made commercial blocking buffers typically contain proprietary protein-free compounds or highly purified single proteins. Using commercial blockers offers benefits such as improved performance compared and longer shelf lives.