m-PEG12-COO-propanoic acid is widely used in bioconjugation and drug delivery systems due to its hydrophilic and biocompatible properties. It serves as a linker or spacer in the modification of peptides, proteins, and other biomolecules, enhancing their solubility and stability. In pharmaceutical applications, it is employed to improve the pharmacokinetics of therapeutic agents by prolonging their circulation time in the body. Additionally, it is utilized in the development of targeted drug delivery systems, where it helps in attaching targeting moieties to drug molecules. Its PEG chain provides steric hindrance, reducing immunogenicity and preventing rapid clearance by the immune system. This makes it valuable in the formulation of advanced therapeutic and diagnostic agents.