This heterobifunctional reagent is primarily utilized in bioconjugation and labeling applications, particularly in biochemistry and molecular biology. It features a maleimide group for selective conjugation to thiol-containing biomolecules (e.g., cysteine residues in proteins or peptides) and an endo-bicyclo[6.1.0]non-4-yn-9-ylmethyl group that enables strain-promoted azide-alkyne cycloaddition (SPAAC), a copper-free click chemistry reaction that is highly efficient, selective, and catalyst-free. The intervening water-soluble 3,6,9-trioxa-12-azapentadecanoyl chain (with 13-oxo amide linkage) acts as a hydrophilic spacer, enhancing compatibility with aqueous biological systems. This makes it valuable for bioimaging, drug delivery systems, and diagnostic tools requiring precise, stable, and bioorthogonal conjugations.