NH-bis(PEG4-acid) is widely used in bioconjugation and drug delivery applications due to its water solubility and biocompatibility. It serves as a linker molecule, enabling the attachment of bioactive molecules, such as drugs or peptides, to nanoparticles, proteins, or other carriers. Its PEG (polyethylene glycol) chains enhance stability and reduce immunogenicity, making it ideal for therapeutic formulations. Additionally, it is utilized in surface modification to improve the hydrophilicity and antifouling properties of materials. In research, it is employed to create crosslinked hydrogels for tissue engineering and controlled release systems. Its bifunctional nature allows for versatile chemical modifications, facilitating its use in targeted drug delivery and diagnostic imaging.