Used in bioconjugation for labeling and crosslinking biomolecules, particularly in fluorescence-based assays and imaging. Its maleimide group reacts selectively with thiol groups (–SH) in cysteine residues, enabling stable linkage to proteins or peptides. The DABCYL moiety acts as a dark quencher, making it ideal for FRET (Förster resonance energy transfer) applications and molecular beacon design. Commonly employed in developing probes for real-time PCR, protease assays, and biosensors where efficient quenching and specific thiol targeting are required.