Radiosynthesis and evaluation of an F-labeled silicon containing exendin-4 peptide as a PET probe for imaging insulinoma.

Background: Analogues of exendin-4 have been radiolabeled for imaging the glucagon-like peptide type 1 receptors (GLP-1R) which are overexpressed in insulinoma. The aim of this research was to synthesize an F-labeled silicon containing exendin-4 peptide (F-) and to evaluate its in vitro and behavior in CHL-GLP-1 receptor positive tumor-bearing mice. F-labeled silicon containing exendin-4 peptide (F-) was prepared via one-step nucleophilic substitution of a silane precursor with F-fluoride in the presence of acetic acid and K222.

Studies toward the development of new silicon-containing building blocks for the direct (18)F-labeling of peptides.

Silicon-containing prosthetic groups have been conjugated to peptides to allow for a single-step labeling with (18)F radioisotope. The fairly lipophilic di-tert-butylphenylsilane building block contributes unfavorably to the pharmacokinetic profile of bombesin conjugates. In this article, theoretical and experimental studies toward the development of more hydrophilic silicon-based building blocks are presented.