Used in bioorthogonal chemistry for rapid and specific labeling of biomolecules in live cells. Enables targeted release of payloads such as drugs or imaging agents through trans-cyclooctene-mediated cleavage. Commonly applied in antibody-drug conjugates (ADCs) and targeted therapy to improve selectivity and reduce off-target effects. Also utilized in pretargeted imaging strategies, where it facilitates high-contrast visualization in vivo by decoupling targeting and signal delivery steps. Its fast reaction kinetics with tetrazine allows efficient conjugation under physiological conditions without interfering with native biochemical processes.