Alkanolammonium Protic Ionic Liquids for Low Temperature (68)~Ga-Radiolabeling of DOTA-Functionalized Compounds

摘要

Nowadays, the radiolabeling of small biomolecules with isotope 68 Ga is one of the important directions in the field of Positron-Emission Tomography (PET). The right choice of buffer for reaction helps to achieve optimal conditions for higher yields. Earlier, we found that protic ionic liquids based on tris(2-hydroxyethyl)ammonium and tris(hydroxymethyl)methyl ammonium salts are suitable buffers for the chelation of the 68 Ga to the PSMA-HBED-CC (a peptide with an acyclic chelator). Herein we describe the labeling of p-SCN-Bn-DOTA (DOTA= 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) chela-tor and peptides (DOTA-NOC, DOTA-TATE, and PSMA-617) with gallium-68 isotope in media of alkanolammonium buffers based on tris(2-hydroxyethyl)ammonium (TEA), tris (hydroxymethyl)methyl ammonium (TRIS) and N-phenyl-bis(2-hydroxyethyl)ammonium (PDA) salts. Besides, for the first time, we present results of low-temperature 68 Ga-complexation in the presence of organic solvents additives. An essential consequence of this study is that for the series of alkanolam-monium buffers, high radiochemical conversions were achieved upon incubation of reaction media under 37°C.