m-PEG2-phosphonic acid is widely used in the field of bioconjugation and surface modification. Its primary application involves attaching to metal oxide surfaces, such as titanium or iron oxide, to improve biocompatibility and reduce non-specific protein adsorption. This makes it valuable in the development of biomedical devices, including implants and sensors, where surface properties are critical for performance. Additionally, it serves as a linker in drug delivery systems, enabling the attachment of therapeutic agents to nanoparticles or other carriers, enhancing targeted delivery and stability. Its hydrophilic PEG moiety also aids in increasing solubility and reducing immunogenicity in biological applications.