This chemical is widely used in bioconjugation and drug delivery systems due to its PEG (polyethylene glycol) spacer, which enhances solubility and reduces immunogenicity. The NH2 group allows for easy attachment to biomolecules like proteins, peptides, or antibodies, while the tBu ester can be deprotected to expose a carboxylic acid for further functionalization. It is particularly useful in creating stable linkers for targeted therapies, improving the pharmacokinetics of therapeutic agents, and facilitating the development of antibody-drug conjugates (ADCs). Additionally, it is employed in surface modification of nanoparticles to improve biocompatibility and circulation time in vivo.