BCN-Osu (CAS No. 1426827-79-3) is a bifunctional bioorthogonal reagent whose molecular structure consists of bicyclo[6.1.0]nonyne (BCN) covalently linked to N-hydroxysuccinimide ester (Osu) via a short linker. The production process starts with BCN-COOH as the raw material, which undergoes activation of the carboxyl group by EDC/NHS to form the Osu ester. The reaction proceeds at room temperature for 10-14 hours, monitored by thin-layer chromatography (TLC), followed by purification through silica gel column chromatography or reverse-phase HPLC, yielding white powder with purity ≥98%. This reagent finds extensive applications in biomolecular labeling (e.g., BCN modification of antibodies/nucleic acids), in vivo imaging (targeting azide-modified tumor cells), and functionalization of drug delivery systems (modifying nanocarriers for targeted conjugation). Its copper-free click chemistry properties and high coupling efficiency (>90%) make it an important tool in chemical biology research.