Used in bioconjugation reactions, particularly in click chemistry applications. Its tetrazine-reactive TCO group enables fast, specific ligation under physiological conditions, making it ideal for labeling biomolecules like peptides, antibodies, and nanoparticles. The carboxylic acid group allows for conjugation to amine-containing biomolecules via amide bond formation, typically using coupling agents such as EDC or HATU, providing flexibility in synthetic workflows.

The PEG4 spacer enhances solubility, reduces aggregation, and improves binding efficiency by minimizing steric hindrance, while also aiding tissue penetration. Commonly applied in drug delivery systems, imaging probes, and the development of biotherapeutics where controlled, site-specific conjugation is required. Also utilized in pretargeted imaging strategies in diagnostic and therapeutic settings.