Used in bioconjugation and drug delivery systems due to its dual PEG linker with a disulfide bond and reactive propargyl and carboxylic acid groups. The disulfide (SS) linker is cleavable under reducing conditions, making it ideal for designing stimuli-responsive therapeutics that release payloads inside cells, particularly in the cytoplasm where glutathione levels are high. The propargyl group enables click chemistry reactions, especially copper-catalyzed azide-alkyne cycloaddition (CuAAC), allowing efficient coupling with azide-containing molecules such as fluorescent tags, peptides, or small molecule drugs. The terminal carboxylic acid can be activated for amide bond formation with primary amines, facilitating attachment to proteins, antibodies, or amine-functionalized surfaces. Commonly used in the synthesis of antibody-drug conjugates (ADCs), targeted nanoparticles, and functionalized PEGylated materials for improved solubility, stability, and biocompatibility.