Used as a hydrophilic linker in bioconjugation chemistry, particularly in the synthesis of antibody-drug conjugates (ADCs) and targeted therapeutics. Its multiple ethylene glycol units enhance solubility and reduce aggregation, while the terminal carboxylic acid allows for stable amide bond formation with amines. The primary amine at one end enables coupling to activated esters or other amine-reactive groups, making it ideal for constructing well-defined, water-soluble conjugates. Frequently employed in pharmaceutical development to improve pharmacokinetic properties and facilitate controlled drug delivery.