Used as a heterobifunctional active ester linker in bioconjugation reactions, featuring an NHS (N-hydroxysuccinimide) ester for efficient coupling to primary amines on peptides, proteins, or other biomolecules, and a maleimide group for selective reaction with thiols (e.g., cysteine residues). The linker includes a PEG4 spacer (7,10,13-trioxa), which enhances solubility and reduces immunogenicity. This structure enables efficient amide and thioether bond formation under mild, aqueous conditions at physiological pH, making it valuable in pharmaceutical development, diagnostic probe synthesis, and biotechnology.

Commonly employed in the preparation of antibody-drug conjugates (ADCs) for targeted cancer therapy, site-specific protein labeling, and functionalized polymers for drug delivery systems. Also utilized in surface modification of medical devices, biosensors, and nanoparticles due to its ability to stably link biomolecules to solid supports while preserving bioactivity. Stable in aqueous solutions, allowing high conjugation efficiency without damaging sensitive biomolecules.