Diazo Biotin-PEG3-azide is useful for introducing a biotin moiety to alkyne-containing biomolecules using Cu(I)-catalyzed Click Chemistry. The hydrophilic spacer arm provides better solubility to the labeled molecules in aqueous media. Diazo allows efficient release of captured biotinylated molecules from streptavidin using sodium dithionite (Na2S2O4).
