Quick Method For ¹⁸F Labeling

Time is of the essence when preparing short-lived radioactive compounds for positron emission tomography (PET) scans. A promising new strategy allows researchers to quickly label biomolecules such as peptides with the commonly used tracer fluorine-18 which has a half-life of only 110 minutes (Angew. Chem. Int. Ed. 2014, DOI: 10.1002/anie.201406258). Many radiolabeled small molecules such as glucose are used to trace malignant activity in PET scans, but peptides offer the promise of greater specificity. However, peptides are much more difficult to label. Now, David M. Perrin of the University of British Columbia and colleagues at the B.C. Cancer Agency have developed a one-step ¹⁸F-radiolabeling method, with which they successfully labeled several peptides as well as an enzyme inhibitor. The group synthesized a new zwitterionic alkylammoniomethyltrifluoroborate compound (AMBF₃), which they attached to three different “radiosynthons,” molecular precursors to the radiolabeling process. These AMBF₃-radiosynthon combinations were readily attached to the tracer biomolecules. Then, the authors performed the crucial tasks of substituting radioactive ¹⁸F for stable F in one step in water and used the tracers to image tumors in mice.