What Types of Click Reactions Are Commonly Used in Histology?

The most commonly used click reactions in histology are:
1. Copper-Catalyzed Azide-Alkyne Cycloaddition (CuAAC): This reaction involves the use of copper as a catalyst to facilitate the reaction between an azide and an alkyne to form a triazole ring.
2. Strain-Promoted Azide-Alkyne Cycloaddition (SPAAC): This copper-free variant is used in contexts where copper can be cytotoxic, relying on the strain energy in cyclooctynes to drive the reaction.
3. Tetrazine-Trans-Cyclooctene Ligation (TCO): This reaction is based on the rapid and bioorthogonal reaction between tetrazines and trans-cyclooctenes.