Used in bioconjugation for click chemistry applications, particularly in drug delivery and biotherapeutics. Enables efficient ligation with tetrazine-modified molecules through fast, catalyst-free reactions. The PEG3 spacer enhances solubility and reduces aggregation, improving bioavailability. Amine group allows for easy coupling to carboxyl, aldehyde, or activated ester groups on proteins, peptides, or surfaces. Commonly applied in labeling, crosslinking, and functionalizing biomolecules for research and diagnostic development.