This compound is widely used in bioconjugation and click chemistry applications due to its azide functional group, which allows for efficient and selective reactions with alkynes via copper-catalyzed azide-alkyne cycloaddition (CuAAC). It is particularly valuable in the modification of biomolecules, such as proteins, peptides, and antibodies, enabling the attachment of fluorescent dyes, drugs, or other functional groups for research and therapeutic purposes. The PEG4 spacer enhances solubility and reduces steric hindrance, making it ideal for creating stable and biocompatible conjugates. Additionally, it is employed in the development of drug delivery systems, where its carboxylic acid group facilitates further functionalization or conjugation to targeting moieties. Its versatility makes it a key tool in chemical biology, materials science, and pharmaceutical research.