What does a block buffer do to the coated plate?
     All of ICT’s unique blocking buffers contain proprietary additives that stabilize the antigenic and functional regions of the coated protein by maintaining the water of hydration during the drying and storage process. These buffers also contain inert additives that block any "sticky" nonspecific binding regions of the adsorbed protein, and any uncoated regions of the polystyrene plate surface. This reduces nonspecific binding of the conjugate and random deposits of sample proteins, thus reducing background noise and increasing the specific signal.
     ICT’s proprietary block buffers also include an antimicrobial agent to prevent bacterial growth during the blocking process (which allows blocking to be done at room temperature) and to extend the useful shelf-life of the plates. Plates can be blocked and dried at room temperature, and stored for 1 year or longer at 2°-°8C, depending on the coated protein.
     ICT’s Block Buffers can be stored up to 12 months at 2°-8°C, and 1 week at room temperature. These Block Buffers are conveniently preformulated in ready-to-use solutions that require no additional preparation. 

How do I use a block buffer? 
     Once your plate has been coated with an antibody or antigen, aspirate or dump out the coating solution, wash the plate 2-4 times, and simply pipette 300-400uL per well of block buffer and let it incubate (ICT recommends a minimum incubation of 3 hours - see How Do I Coat Plates? for the full coating procedure).  

General Blocker with BSA (BB1)
     Universal Blocker contains a mammalian protein blocking agent (based on BSA) suitable for most monoclonal and polyclonal antibody capture ELISA formats, and peptide and protein antigen-down ELISA formats. This unique block buffer contains proprietary protein stabilizers that provide a long-term stabilizing environment for dried antigen or antibody coat proteins, while minimizing nonspecific binding interactions during the assay process.  

Neptune Block with Nonmamalian Blockers (BB2) 
     Neptune Block contains a proprietary non-mammalian formulation based on fish proteins, plus molecular stabilizers that provide a high degree of blocking efficiency. Neptune Block was designed for antigen-down ELISA formats, and for sandwich assays with high background problems. 
     This formulation is a heterogeneous mixture of small molecules capable of blocking both the nonspecific binding sites of the adsorbed protein, as well as the unoccupied regions of the polystyrene plate that are not sterically accessible to larger traditional mammalian blocking reagents, thereby reducing background noise. The small size of these unique blockers results in minimal steric hindrance to key epitope regions of target coated proteins, thus enhancing specific signal generation.
     As Neptune Block contains a non-mammalian protein blocking agent, it is antigenicity foreign to most mammalian immune systems. In antigen-down ELISA formats, this reduces the possibility of false-positives generated from endogenous antibodies in the sample reacting with plate blocking proteins. Neptune Block is particularly useful when working with human, swine, and bovine serum samples, as there is little interaction with the blocking molecules resulting in lower backgrounds.

SynBlock with Tween and Synthetic Blockers (BB3)
     SynBlock is a novel non-protein blocking formulation designed to eliminate interference and nonspecific background noise associated with antibody-coated ELISA formats and sandwich ELISAs. Because SynBlock contains inert nonreactive blockers, it reduces the amount of nonspecific binding of enzyme-labeled conjugates to blocked plate surfaces. Use of this blocking formulation provides superior background performance without the use of conventional cross-reactive protein additives.  

Optimization Pack - save 15%! 
      To create the best assay possible, sometimes it's best to just try each block buffer and see which one has the lowest backgrounds and highest specific signal in your assay system. Buy the optimization pack to receive 100mL of each block buffer and save 15%! 
     The optimization pack (catalog #957) includes one 100mL bottle of each of our first 2 blockers: catalog #632 BB1, #62 BB2, and #641 BB3.

Phosph-Free Blocker (BB4)
     Phosph-Free Blocker does not contain any phosphates, nor does it contain any animal proteins. It is designed for ELISAs using alkaline phophatase detection systems, and for ELISAs with super sensitivity requirements. It is ideal for microfluidics systems, for chemically treated and glass ELISA plates. BB4 is not included in the Optimization Pack as it is typically used in alkaline phosphate assays.