mPEG-ALD is widely used in bioconjugation and drug delivery systems due to its aldehyde functional group, which allows for efficient and selective coupling with amine-containing molecules. It is commonly employed in the modification of proteins, peptides, and nanoparticles to enhance their stability, solubility, and circulation time in the body. In drug delivery, it is utilized to create PEGylated therapeutics, which can reduce immunogenicity and improve pharmacokinetics. Additionally, it plays a key role in surface modification of biomaterials and in the development of targeted therapies by enabling precise attachment of ligands or targeting moieties. Its applications also extend to research tools for studying biomolecular interactions and cellular uptake mechanisms.