Radiolabeling by aluminum fluoride-18 complexation: method optimization on a NODA-based model for application to sensitive biomolecule as PET tracers for oncology
Radiomarquage par complexation de 18-fluorure d'aluminium : optimisation de la méthode sur un modèle dérivé de NODA en vue d'applications à des biomolécules sensibles comme traceurs TEP pour l'oncologie
Résumé
Fluorine-18 (18F) is the most favorable positon emitter for tumor imaging. However, direct 18F labeling of biomolecules is challenging as it involves multiple steps and stringent conditions that are generally not suitable for biomolecules whose integrity may be altered. Over the past decade, an elegant new approach has been developed by coordination of aluminum fluoride {Al-18F}.(a) The objective of this work was to implement such a method and to find the mildest conditions compatible with heat- or acid-sensitive biomolecules. To evaluate {Al-18F} complexation, NODA MP C4 was prepared as a model compound from the commercially available NODA MP NCS (Figure). This model bears a thiourea function to mimic that present in the final conjugates. The corresponding radioactive complex Al18F NODA MP C4 was obtained following the most common reported radiofluorination conditions (pH 4, buffer AcO/AcOH, reflux). Based on this preliminary result, several parameters have been varied to obtain the highest radiochemical yield (RCY) under the mildest conditions. To this end and to guide the operational conditions in radiochemistry, a complementary study in cold series was performed in parallel. Al18F NODA MP C4 was obtained with a reproducible satisfactory RCY on comparison with reported results on NODA derivatives.(b,c) Herein, we will present and discuss the optimization study.
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