Carboxy-PEG2-sulfonic acid is widely used in bioconjugation and surface modification due to its bifunctional properties. The carboxylic acid group allows for easy coupling with amines or other reactive groups, making it valuable in the development of drug delivery systems, where it can link therapeutic agents to targeting molecules. The sulfonic acid group enhances water solubility and stability, which is beneficial in creating hydrophilic coatings for medical devices or nanoparticles. Additionally, it is employed in the synthesis of hydrogels and functionalized polymers for biomedical applications, such as tissue engineering and biosensors. Its ability to modify surfaces also makes it useful in improving the biocompatibility of implants and diagnostic tools.