A new¹⁸F-heteroaryltrifluoroborate radio-prosthetic with greatly enhanced stability that is labelled by¹⁸F–¹⁹F-isotope exchange in good yield at high specific activity

Abstract

An 18F-heteroaryltrifluoroborate was designed as a novel radioprosthetic for PET imaging. The stability of the new prosthetic was confirmed using 19F-NMR spectroscopy: the solvolytic half-life was measured to be >16 000 min. Conjugation to RGD gave a stable radiotracer precursor for kit-like labeling by 18F–19F isotope exchange in 15 min. The total radiosynthetic procedure including HPLC purification requires <45 min. A plasma stability assay showed negligible defluoridation following 150 min and stability is corroborated by in vivo imaging showing minimal bone uptake. With Curie levels of 18F–fluoride, yields of 20% and specific activities as high as 3 Ci μmol−1 (110 GBq μmol−1) are achieved (n = 3).