Used in bioconjugation to modify proteins, peptides, or nanoparticles, enhancing water solubility and stability while reducing immunogenicity. Commonly applied in drug delivery systems to prolong circulation time of therapeutic agents. Serves as a linker in PEGylation due to its reactive carboxylic acid end group, enabling coupling with amine-containing molecules. Also utilized in the formulation of PEG-based hydrogels and surface coatings for biomedical devices.