Used in bioconjugation processes to link proteins, peptides, or other biomolecules with polyethylene glycol (PEG) chains. The NHS ester reacts efficiently with primary amines on biomolecules, forming stable amide bonds, while the maleimide group selectively attaches to thiol groups, enabling site-specific conjugation. Commonly applied in the development of PEGylated therapeutics to improve solubility, stability, and circulation time of biopharmaceuticals. Also utilized in creating crosslinked hydrogels and functionalized surfaces for diagnostic assays and drug delivery systems.