Synthesis and Characterization of ¹⁸F-FBEM-NGA as a Potential ASGP Receptor Imaging Agent

A ¹⁸F-labelling prosthetic group named as N-2-(4-¹⁸F-fluorobenzamido) ethyl maleimide (¹⁸F-FBEM) was prepared for peptides and protein labeling, and the radiopharmaceuticals prepared from this prosthetic group were designed for positron emission tomography (PET) imaging. This prosthetic group was synthesized by the reaction of Nsuccinimidyl 4-¹⁸F-fluorobenzoate (¹⁸F-SFB) with N-(2-aminoethyl) maleimide trifluoroacetate salt. The total synthesis time from ¹⁸F- to ¹⁸F-FBEM was about 2.5 h with decay corrected radiolabeling yield of 9.8%. The double bond contained in maleimide of the synthon can react with sulfhydryl groups with high efficiency under room temperature, thus it can be applied in indirect radiofluorinations of thiol-containing molecules such as peptides and protein. ¹⁸F-labeled galactosyl-neoglycoalbumin (¹⁸F-FBEM-NGA) was developed based on ¹⁸F-FBEM for example.