mPEG-ALD is widely used in bioconjugation and drug delivery systems due to its reactive aldehyde group, which enables efficient coupling with amino groups in proteins, peptides, and other biomolecules. It is commonly employed to modify therapeutic proteins, enhancing their stability, solubility, and circulation time in the body. This chemical is also utilized in the development of PEGylated drugs, where it helps reduce immunogenicity and improve pharmacokinetics. Additionally, mPEG-ALD is applied in surface modification of nanoparticles and liposomes, facilitating targeted drug delivery and improving biocompatibility. Its role in creating hydrogels and biomaterials for tissue engineering further highlights its versatility in biomedical applications.