Abstract
Fluorine-18 labeling of biomolecules is mostly performed by an indirect labeling method using a prosthetic group. Fluorine-18 labeled 6-fluoronicotinic acid-2,3,5,6-tetrafluorophenyl ester is a useful prosthetic group to radiolabel a protein. Recently, we reported an improved preparation of this prosthetic group. To test the conjugation efficiency of the labeled ester prepared by this method, we have performed conjugation reactions with a peptide, a protein, and a small molecule. Prostate-specific membrane antigen targeting small molecule [(18) F]DCFPyL, αvβ3 integrin receptors targeting peptide [(18) F]c(RGDfK) and [(18) F]albumin were prepared in good radiochemical yields. The conjugation reactions were completed at 40°C to 50°C in 10 minutes. The overall radiochemical yield was 25% to 43% in 30 to 45 minutes.