Used in bioconjugation and labeling applications, particularly in the field of biomedical research. It serves as a linker molecule for attaching biomolecules, such as proteins or peptides, to other compounds or surfaces. The PEG (polyethylene glycol) chain provides flexibility and solubility, while the carboxylic acid group allows for further functionalization or conjugation. This chemical is often employed in drug delivery systems, diagnostic assays, and the development of targeted therapies due to its ability to enhance stability and reduce immunogenicity.