摘要：

Integrins have become increasingly attractive targets for molecular imaging of angiogenesis with positron emission tomography or single‐photon emission computed tomography, but the reliable production of radiopharmaceuticals remains challenging. A strategy for chemoselective labeling of the integrin ligand—c(RGDyK) peptide—has been developed on the basis of the Cu(I)‐catalyzed conjugation reaction. Recently, we reported a nucleophilic detagging and fluorous solid‐phase extraction method providing an easy way to implement an approach for obtaining 2‐[F]fluoroethyl azide. In this work, we report the practical use of this method for the preparation of the 2‐[F]fluoroethyl‐triazolyl conjugated c(RGDyK) peptide: [F]FtRGD. The two‐step, two‐pot synthesis, HPLC purification, and reformulation could be readily performed with a standard nucleophilic radiofluorination synthesizer (GE TRACERlab FX), with minimal modifications. [F]FtRGD was obtained in a solution for injection (>500 MBq/mL) in 10–30% nondecay‐corrected radiochemical yield, excellent radiochemical purity (>98%), and 28 ± 13 GBq/µmol specific activity. [F]FtRGD ( = 54 ± 14 nM for αβand 1.7 ± 0.2 nM for ) was evaluated in mice and showed good stability in vivo, good tumor‐to‐background ratio (1.6 ± 0.3 %ID/g at 1.5 h post‐injection in U87‐MG tumors), and rapid urinary excretion. Therefore, [F]FtRGD proved valuable for preclinical positron emission tomography imaging of integrin expression.

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