Sulfo-EMCS is widely used in bioconjugation for linking proteins, peptides, or other biomolecules to surfaces or labeling agents. It reacts selectively with primary amines (e.g., lysine residues or N-termini of proteins) to form stable amide bonds, making it ideal for immobilizing antibodies, enzymes, or antigens onto amine-reactive supports. Due to its water solubility, Sulfo-EMCS is especially useful in aqueous reaction systems without requiring organic solvents, which helps maintain protein stability. It is commonly employed in the preparation of protein-protein conjugates, immobilization on biosensor chips, and crosslinking in immunoassays. The sulfo group enhances solubility and reduces nonspecific binding, improving conjugation efficiency in biological applications.