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Copolymer of N-vinylpyrrolidone (VP) with vinylformamide (VFA) and N-vinyliminodiacetic acid (VIDA) was synthesized; its metal-polymer complexes (MPCs) with gallium were obtained. The complexes were characterized by size exclusion chromatography, hydrodynamic and optical methods, scanning electron microscopy, and spectral methods (UV, IR, 1Н NMR spectroscopy). It was demonstrated that in going from polymer to complex, hydrodynamic parameters of macromolecules change only slightly, although the polymer contains intramolecular Ga(VIDA)2 fragments in its structure. A new method for preparation of MPCs with gallium and gallium-68 radionuclide was suggested. The obtained metal-polymer complex is stable over a wide range of pH values as well as in the histidine challenge reaction. In vivo distribution experiments in intact animals showed high primary accumulation of thegallium-68 MPC in blood with subsequent excretion via urinary tract.

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Nowadays, the radiolabeling of small biomolecules with isotope 68Ga 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 68Ga 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) chelator 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 68Ga‐complexation in the presence of organic solvents additives. An essential consequence of this study is that for the series of alkanolammonium buffers, high radiochemical conversions were achieved upon incubation of reaction media under 37 °C.