Click chemistry describes a class of chemical reactions that use bio-orthogonal or biologically unique moieties to label and detect a molecule of interest in mild, aqueous conditions. The click reaction involves a copper-catalyzed triazole formation from an azide and an alkyne. The azide and alkyne moieties can be used interchangeably; either one can be used to tag the molecule of interest, while the other is used for subsequent detection.

The biotin azide is reactive with terminal alkyne via a copper-catalyzed click reaction. Biotin can be subsequently detected with streptavidin, avidin or NeutrAvidin? biotin-binding protein.

Efficiency—the click reaction is complete in less than 1 hour;

Specificity—the reaction between the label and detection tag is selective and specific;

Stability—the reaction product contains an irreversible, covalent bond;

Biologically inert—the components of the reaction do not undergo any side reactions.