pharmaceuticals Article 68Ga-Labeling: Laying the Foundation for an Anti-Radiolytic Formulation for NOTA-sdAb PET Tracers Henri Baudhuin 1,*, Julie Cousaert 2, Philippe Vanwolleghem 1, Geert Raes 3,4 , Vicky Caveliers 1,2, Marleen Keyaerts 1,2 , Tony Lahoutte 1,2 and Catarina Xavier 1 1 Department of Medical Imaging (MIMA), Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels, Belgium;
[email protected] (P.V.);
[email protected] (V.C.);
[email protected] (M.K.);
[email protected] (T.L.);
[email protected] (C.X.) 2 Nuclear Medicine Department (NUCG), Universitair Ziekenhuis Brussel (UZ Brussel), Laarbeeklaan 101, B-1090 Brussels, Belgium;
[email protected] 3 Unit of Cellular and Molecular Immunology (CMIM), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium;
[email protected] 4 Myeloid Cell Immunology Laboratory (MCI), VIB Center for Inflammation Research, Pleinlaan 2, B-1050 Brussels, Belgium * Correspondence:
[email protected]; Tel.: +32-2-477-4991 Abstract: During the preparation of [68Ga]Ga-NOTA-sdAb at high activity, degradation of the tracers was observed, impacting the radiochemical purity (RCP). Increasing starting activities in radiolabelings is often paired with increased degradation of the tracer due to the formation of free radical species, a process known as radiolysis. Radical scavengers and antioxidants can act as radioprotectant due to their fast interaction with formed radicals and can therefore reduce the degree of radiolysis. This study aims to optimize a formulation to prevent radiolysis during the labeling of 68 Citation: Baudhuin, H.; Cousaert, J.; NOTA derivatized single domain antibody (sdAbs) with Ga.