New AlF chelators for fluorine-18 radiolabeling of biomolecules

Positron emission tomography (PET) uses a PET scanner to track radioactive molecules in the body. Fluorine-18 (18F, a radioactive form of fluorine) is a frequently used radionuclide used in PET. The chemical incorporation of 18F into biological molecules (biomolecules) allows visualization of the binding of the biomolecule to its target in the body using a PET scanner. The Al18F method allows to incorporate 18F in various biomolecules in a short procedure which is important as the radioactivity of fluorine-18 decreases with 50% every 2 h due to radioactive decay. The Al18Fstrategy involves chemical binding (“chelation”) of Al18F to a dedicated binding molecule (“chelator”) which is in turn chemically bound to the biomolecule that needs to be tracked in the body. Recently, we developed a new Al18F chelating agent (RESCA1), that allows chelation at room temperature. This is important as biologicals are frequently unstable at higher temperatures. Promising results were obtained with RESCA1, including radiolabelling at ambient temperatures (≤40 °C) of the temperature sensitive protein human serum albumin (HSA) and maintaining stability up to 4h after intravenous injection in rats. Therefore, RESCA1 is promising for labelling of heatsensitive biomolecules in general with 18F. This project will look deeper into the chemistry of the chelator and will apply the technology to radiolabel different biomolecules with 18F for visualization of specific tumors using a PET scanner.