Hexafluorobenzene (HFB) reacts with free thiols to produce a unique and selective perfluoroaromatic linkage between two sulfurs. We modified this chemical reaction to produce dimeric 18F-RGD-tetrafluor-obenzene (TFB)-RGD, an integrin αvβ3 receptor ligand. 18F-HFB was prepared by a fluorine exchange reaction using K18F/K2.2.2 at room temperature. The automated radiofluorination was optimized to minimize the amount of HFB precursor and, thus, maximize the specific activity. 18F-HFB was isolated by distillation and subsequently reacted with thiolated c(RGDfk) peptide under basic and reducing conditions. The resulting 18F-RGD-TFB-RGD demonstrated integrin receptor specific binding, cellular uptake, and in vivo tumor accumulation.18F-HFB can be efficiently incorporated into thiol-containing peptides at room temperature to provide novel imaging agents.
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