Immunohistochemistry Resource Guide

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Blocking Background Signal

Blocking agents minimize background signal from endogenous enzyme activity, biotin, and non-specific binding of tissue elements (charged particles, macromolecules, Fc receptors) with detection reagents.

Endogenous alkaline phosphatase (AP) and peroxidase (HRP) activities in frozen, acetone-fixed intestine revealed with Vector® Red AP Substrate (magenta) and ImmPACT™ DAB HRP Substrate (brown), (left). Same substrates used on BLOXALL™ Solution-treated tissue (right). BLOXALL™ Blocking Solution completely eliminates both endogenous enzyme activities.

BLOXALL™ Endogenous Peroxidase/Alkaline Phosphatase Blocking Solution

Tissues may contain endogenous peroxidase, pseudoperoxidase, and/or alkaline phosphatase activity that will produce background staining. BLOXALL™ Endogenous Peroxidase/Alkaline Phosphatase Blocking Solution inactivates each of these enzymes in one step.

  • Compatible with formalin-fixed, paraffin-embedded tissue sections, frozen tissue sections, and cell preparations
  • Ready-to-use in a convenient dropper bottle
  • More effective than conventional blocking methods
  • Brief 10-minute incubation

Levamisole Solution

  • Levamisole Solution specifically inhibits endogenous alkaline phosphatase activity.
  • Can be added to the alkaline phosphatase substrate solution
  • Does not inhibit the isoenzyme used for the VECTASTAIN® ABC-AP reagents, ImmPRESS™- AP Reagents and other alkaline phosphatase conjugates
  • Ready-to-use in a convenient dropper bottle

2.5% Normal Sera

Our 2.5% Normal Sera are pooled samples collected from healthy adult animals.

  • Heat-treated and centrifuged to remove precipitates and then filtered
  • Tested for cross-reactivities
  • Can be used for blocking non-specific binding or as an antibody diluent

Bovine Serum Albumin (BSA)
Immunohistochemical Grade.

  • Can be used as a diluent or a blocking agent
  • Free of impurities present in other grades of BSA, which can introduce artifacts or increase background staining in IHC staining, ELISAs, or blots

10x Casein Solution

10x Casein Solution is a general blocking agent for IHC, nucleic acid blotting, protein blotting, and other applications.

Carbo-Free™ Blocking Solution

Carbo-Free Blocking Solution is a protein-based agent that is essentially free of glycoproteins. It is ideal for applications using lectins in which glycoprotein contamination could generate background staining or false positive results.

  • Can be used to block non-specific binding or as an antibody diluent

Animal-Free Blocker™ (5x concentrate solution)

Animal-Free Blocker™ is a plant-derived blocking agent and diluent for IHC, nucleic acid blotting, protein blotting, and other applications. This reagent contains no animal-derived protein and can be used as an alternative to sera, BSA, casein, or non-fat dry milk.

Streptavidin/Biotin Blocking Kit

Streptavidin/Biotin Blocking Kit blocks all endogenous biotin, biotin receptors, and streptavidin binding sites present in tissues to prevent non-specific binding of streptavidin or biotinylated reagents with biotin/streptavidin detection systems. Ready-to-use in a convenient dropper bottle.

Avidin/Biotin Blocking Kit

The Avidin/Biotin Blocking Kit blocks all endogenous biotin, biotin receptors, and avidin binding sites present in tissues to prevent non-specific binding of avidin or biotinylated reagents with avidin-biotin detection systems. Ready-to-use in a convenient dropper bottle.

R.T.U. Animal-Free Block and Diluent

This plant protein-derived product is a universal antibody diluent and blocking reagent intended for cell- and tissuebased IHC and IF applications. This ready-to-use solution can be used as an alternative to normal sera, BSA, casein and non-fat dry milk.

R.T.U. Animal-Free Block and Diluent is supplied without any sodium azide. It can therefore be used with both peroxidase and alkaline phosphatase antibody conjugates and all secondary detection reagents including polymer systems and avidin/biotin reagents that incorporate these enzymes. This makes the blocking solution especially convenient in multiple antigen labeling IHC applications in which antibodies from different species and a variety of detection systems are used on the same tissue section.

R.T.U. Animal-Free Block and Diluent is a unique formulation different from our concentrated (5x) animal-free blocker. It has been designed with optimized conditions and neutral pH specifically for IHC and IF methods.

Normal Sera

Our Normal Sera are pooled samples collected from healthy adult animals. The serum is heat-treated and centrifuged to remove precipitates and then filtered. Each serum is tested with the appropriate antibody to check for possible crossreactivities. The sera can be used to block non-specific binding or as an antibody diluent.

ProductCatalog Number
BLOXALL™ Blocking Solution SP-6000
Levamisole Solution SP-5000
Avidin/Biotin Blocking Kit SP-2001
Streptavidin/Biotin Blocking Kit SP-2002
Normal Goat Serum S-1000
Normal Horse Serum S-2000
Normal Chicken Serum S-3000
Normal Swine Serum S-4000
Normal Rabbit Serum S-5000
2.5% Normal Goat Serum S-1012
2.5% Normal Horse Serum S-2012
Bovine Serum Albumin (BSA) SP-5050
10x Casein Solution SP-5020
Carbo-Free™ Blocking Solution SP-5040
R.T.U. Animal-Free Block and Diluent SP-5035
Animal-Free Blocker™ SP-5030
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