Widely used in bioconjugation, especially in click chemistry applications. Its main role is to link biomolecules such as proteins, peptides, or antibodies with thiol-containing compounds under mild, aqueous conditions. The maleimide group reacts selectively with thiols to form stable thioether bonds, while the DBCO (dibenzocyclooctyne) group enables copper-free click reactions with azide-labeled molecules. This dual functionality makes it ideal for labeling, crosslinking, or modifying biomolecules in live cells or sensitive biological systems where copper catalysts are toxic or disruptive. Commonly used in drug delivery systems, antibody-drug conjugates (ADCs), and fluorescent probe development. The C3 spacer provides flexibility and helps reduce steric hindrance, improving reaction efficiency.