Mal-PEG2-NHS Ester is widely used in bioconjugation and chemical biology for modifying proteins, peptides, and other biomolecules. Its key application lies in linking thiol-containing molecules (via the maleimide group) to amine-containing molecules (via the NHS ester group), enabling the creation of stable crosslinked complexes. This reagent is particularly valuable in antibody-drug conjugate (ADC) development, where it facilitates the attachment of cytotoxic drugs to antibodies for targeted cancer therapy. It is also employed in surface functionalization of nanoparticles and biomaterials, enhancing their biocompatibility and targeting capabilities. Additionally, Mal-PEG2-NHS Ester is utilized in the study of protein-protein interactions and the development of biosensors, where precise molecular conjugation is essential. Its water-soluble PEG spacer improves solubility and reduces steric hindrance, making it a versatile tool in drug delivery and diagnostic applications.