Methylamino-PEG4-acid is widely used in the field of bioconjugation, where it serves as a linker molecule to connect various bioactive compounds, such as peptides, proteins, or drugs, to other molecules or surfaces. Its PEG (polyethylene glycol) spacer enhances solubility and reduces immunogenicity, making it valuable in drug delivery systems. It is also employed in the development of antibody-drug conjugates (ADCs) and targeted therapies, where it helps improve the stability and bioavailability of therapeutic agents. Additionally, it finds applications in biochemical research for modifying biomolecules to study their interactions or functions in biological systems.