DOTA-NHS-ester is widely used in the field of radiopharmaceuticals for the chelation of metal ions, particularly in the development of diagnostic and therapeutic agents. It is commonly employed to label peptides, antibodies, and other biomolecules with radionuclides such as gallium-68, lutetium-177, and yttrium-90 for use in positron emission tomography (PET) imaging and targeted radiotherapy. The NHS-ester group allows for efficient conjugation to primary amines on biomolecules, ensuring stable and site-specific labeling. This makes it a valuable tool in cancer research and treatment, enabling precise targeting of tumor cells while minimizing damage to healthy tissues. Additionally, it is utilized in molecular imaging studies to investigate biological processes and disease mechanisms at the cellular level.