m-PEG5-sulfonic acid is widely used in bioconjugation and drug delivery systems due to its water-soluble and biocompatible properties. It is often employed to modify proteins, peptides, and other biomolecules to enhance their solubility and stability in aqueous environments. The sulfonic acid group allows for strong ionic interactions, making it useful in purification processes such as ion-exchange chromatography. Additionally, it is utilized in the development of targeted drug delivery systems, where its PEG chain helps reduce immunogenicity and prolong circulation time in the body. This chemical is also applied in the synthesis of hydrogels and other biomaterials, where its hydrophilic nature improves the overall performance of the material in biomedical applications.