Used as a crosslinking agent in bioconjugation processes, enabling the attachment of biomolecules such as proteins, peptides, or antibodies to other molecules or surfaces. Its azido group allows for efficient click chemistry reactions, particularly with alkyne-functionalized compounds, making it valuable in drug delivery systems, diagnostic assays, and material science. The PEG4 spacer enhances solubility and reduces steric hindrance, improving the efficiency of conjugation. Additionally, the methyl ester group can be hydrolyzed to a carboxylic acid, providing further functionalization opportunities for creating complex molecular architectures.