Used in bioconjugation for targeted drug delivery, particularly in antibody-drug conjugates (ADCs). Its maleimide group reacts selectively with thiol groups on proteins, while the disulfide linker provides controlled release in reducing environments like inside cells. The terminal carboxylic acid (propionic acid) enables coupling to primary amines on biomolecules after activation (e.g., to NHS ester). This heterobifunctional crosslinker facilitates stable conjugation with cleavable linkage, making it valuable in developing therapeutics with improved specificity and reduced off-target effects.