ИСТИНА

Unique properties of fullerenes, especially endohedral metallofullerenes (EMFs) and their derivatives find increasingly wide acceptance in basic science and applied technologies. During the last decade, they are in demand in up-to-date energy systems and fine-chemical and drug synthesis. Recently, much attention has been paid to their use in medicine (e.g., MRI contrast agents, radiopharmaceuticals etc.). Nonetheless, aqueous dispersions of fullerenes (AFDs) show certain difficulties and often call for chemical modification or the use of toxic organic solvents. Currently, there is a lack of sufficient methodology for accurate identification of the aggregation, size, surface alteration, quantitative determination etc. Y@C82 is the most stable type of EMF and it can be used as a model EMF system. Gd@C82 can be useful for a medical application as a MRI agent after obtaining AFD. Thus, the aim of this study is to develope approaches to the synthesis and characterization of AFD C60, C70, and metallofullerenes. The solvent-exchange process was applied to obtaining AFDs. Using UV/vis/NIR, optical spectra was registered and apparent molar absorptivities were calculated along with the data on a total organic carbon analyzer. LODs for both fullerene C60 and C70 were ca. 10µМ. ICP-AES was used for quantitationof metallofullerene aqueous dispersions. The total yield determined under the optimum synthesis conditions was 1-10%. Headspace GC/MS was used to analyze volatile compounds (benzeneetc.); the quantity of the hazardous organic matter was no more 1 ppb after the purification by solid-phase extraction. We have studied the forms of fullerenes existence in the AFD. Gd@C82 AFDs were tested as MRI contrast agents and compared with commercially available Magnevist MRI contrast agent. The results of relaxation times (T1) study are presented in the report. Acknowledgements The work is supported by the grants of the Russian Foundation for Basic Research no. 16-33-00654 mol_a (I.V. M.), 16-03-00810-a (I.E.K.) and 17-03-00713-a (V.P.B.).