This chemical is widely used in bioconjugation and click chemistry applications. It serves as a linker for attaching biomolecules, such as proteins, peptides, or antibodies, to other molecules or surfaces. The endo-BCN group enables efficient and selective reactions with azide-containing compounds through strain-promoted azide-alkyne cycloaddition (SPAAC), a type of click chemistry. The PEG4 spacer enhances solubility and flexibility, reducing steric hindrance during conjugation. The NHS ester group allows for straightforward coupling with primary amines, making it ideal for labeling or modifying biomolecules. This compound is particularly valuable in drug delivery, diagnostics, and the development of bioconjugates for research and therapeutic purposes.