This compound is widely used in bioconjugation and click chemistry applications. Its TCO (trans-cyclooctene) group enables rapid and efficient reactions with tetrazine derivatives, making it valuable for labeling biomolecules such as proteins, antibodies, and peptides. The PEG9 spacer enhances solubility and reduces steric hindrance, improving the efficiency of conjugation. The maleimide group allows for specific attachment to thiol-containing molecules, such as cysteine residues in proteins. This makes it a versatile tool in drug delivery, diagnostics, and targeted imaging, particularly in the development of antibody-drug conjugates (ADCs) and fluorescence-based probes. Its stability and reactivity under physiological conditions further enhance its utility in biomedical research and therapeutic applications.