Used in surface modification to introduce hydrophilic, biocompatible layers on materials. Commonly applied in bioconjugation, where the COOH group reacts with amine-containing biomolecules like proteins or antibodies, enabling the development of diagnostic assays and biosensors. Enhances stability and reduces non-specific binding in biological environments. Employed in drug delivery systems to improve nanoparticle dispersion and circulation time. Also utilized in tissue engineering scaffolds to promote cell adhesion and support functionalization with bioactive molecules.