m-PEG12-COOH is widely used in bioconjugation and drug delivery systems due to its ability to improve solubility, stability, and bioavailability of therapeutic compounds. It is commonly employed to modify proteins, peptides, and nanoparticles, enhancing their circulation time in the body and reducing immunogenicity. In pharmaceutical research, it serves as a linker for attaching targeting ligands or drugs to carriers, enabling controlled release and targeted delivery. Additionally, it is utilized in the development of hydrogels and biomaterials for tissue engineering, where its hydrophilic properties and biocompatibility are advantageous. Its carboxyl group allows for further functionalization, making it a versatile tool in various biomedical applications.