PEG4-sulfonic acid is widely utilized in biochemical and pharmaceutical research due to its water solubility and ability to modify biomolecules. It is often employed as a linker or spacer in drug delivery systems, enhancing the stability and bioavailability of therapeutic compounds. In bioconjugation, it facilitates the attachment of drugs, peptides, or proteins to nanoparticles or other carriers, improving targeting efficiency. Additionally, its sulfonic acid group makes it useful in ion-exchange chromatography for separating and purifying biomolecules. Its PEG (polyethylene glycol) component also reduces immunogenicity, making it suitable for applications in drug formulation and protein engineering.