mPEG-ALD is widely used in bioconjugation and drug delivery systems due to its reactive aldehyde group, which allows for efficient coupling with amine-containing molecules. It is commonly employed to modify proteins, peptides, and nanoparticles, enhancing their stability, solubility, and circulation time in the body. This makes it valuable in the development of therapeutic agents, such as PEGylated drugs, which exhibit reduced immunogenicity and improved pharmacokinetics. Additionally, mPEG-ALD is utilized in the preparation of hydrogels and biomaterials for tissue engineering, where it facilitates crosslinking and controlled release of bioactive molecules. Its applications also extend to diagnostic tools, where it is used to label biomolecules for imaging and detection purposes.