Arylboronates capture aqueous (18)F-fluoride in one step to afford a highly polar (18)F-labeled aryltrifluoroborate
anion ((18)F-ArBF(3) (-)) that clears rapidly in vivo. To date however, there is little data to show that a
ligand labeled with a prosthetic (18)F-ArBF(3) (-) will provide functional images. RGD, a high-affinity
ligand for
integrins that are present on the cell surface of numerous
tumors, has been labeled in many formats with many different
radionuclides, and as such represents a well-established
ligand that can be used to evaluate new labeling methods. Herein we have labeled RGD with a prosthetic (18)F-ArBF(3) (-) via two approaches for the first time: 1) a RGD-boronate bioconjugate is directly labeled in one step and 2) an
alkyne-modified arylborimidine is first converted to the corresponding (18)F-ArBF(3) (-) which is then conjugated to an RGD-
azide via Cu(+)-mediated [2+3] dipolar cycloaddition in one pot over two steps. RGD-(18)F-ArBF(3) (-) bionconjugates were produced in reasonable radiochemical yields using low amounts of (18)F-
fluoride anion (10-50 mCi). Despite relatively low specific activities, good
tumor images are revealed in each case.