Used in bioconjugation to link biomolecules such as peptides, proteins, or antibodies with other compounds like fluorescent dyes, drugs, or nanoparticles. The maleimide group reacts selectively with thiol groups (-SH), commonly found in cysteine residues, enabling site-specific conjugation. The PEG3 spacer improves solubility, reduces aggregation, and increases the stability of the conjugate in biological environments. The PFP ester end reacts efficiently with primary amines (-NH2), allowing attachment to lysine residues or amine-containing molecules. Commonly used in the development of antibody-drug conjugates (ADCs), targeted therapies, and diagnostic probes. Its bifunctional design supports controlled, two-step conjugation strategies in pharmaceutical and research applications.