6-FAM BCN

6-FAM BCN is a clickable derivative of 6-carboxyfluorescein (6-FAM) commonly used for labeling biomolecules such as oligonucleotides. 6-FAM is a well-characterized green fluorescent dye known for its high brightness and photostability. To minimize steric hindrance and reduce potential interference with biomolecular interactions after conjugation, the molecule incorporates a polyethylene glycol (PEG) spacer. The bicyclononyne (BCN) moiety enables strain-promoted azide-alkyne cycloaddition (SPAAC) with azido groups, forming stable triazole linkages under catalyst-free conditions. In addition, unlike dibenzocyclooctyne (DBCO), BCN also reacts efficiently with tetrazines through an inverse electron-demand Diels-Alder (IEDDA) reaction. This reaction is rapid, selective, and bioorthogonal, allowing labeling of biomolecules under physiological conditions without the need for metal catalysts or disruption of native biological processes.