The use of targeted drug delivery systems, including those based on selective absorption by certain receptors on the surface of the target cell, can lead to a decrease in the minimum effective dose and the accompanying toxicity of the drug, as well as an increase in therapeutic efficacy. A fullerene C60 conjugate (FA-PVP-C60) with polyvinylpyrrolidone (PVP) as a biocompatible spacer and folic acid (FA) as a targeting ligand for tumor cells with increased expression of folate receptors (FR) was obtained. Using 13C NMR spectroscopy, FT-IR, UV-Vis spectrometry, fluorometry and thermal analysis, the formation of the conjugate was confirmed and the nature of the binding of its components was established. The average particle sizes of the conjugate in aqueous solutions and cell culture medium were determined using dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). The FA-PVP-C60 showed antiradical activity against •DPPH, •OH and O2•−, but at the same time, it was shown to generate 1O2. It was found that the conjugate in the studied concentration range (up to 200 μg/mL) is non-toxic in vitro and does not affect the cell cycle. To confirm the ability of the conjugate to selectively accumulate through folate-mediated endocytosis, its uptake into cells was analyzed by flow cytometry and confocal microscopy. It was shown that the conjugate is less absorbed by A549 cells with low FR expression than by HeLa, which has a high level of expression of this receptor.

Viral infections and many other dangerous diseases are accompanied by the development of oxidative stress, which is a consequence of an increase in the level of the reactive oxygen species (ROS). In this regard, the search for effective antioxidants remains highly relevant. We tested fullerenol C60(OH)36 in the context of the connection between its self-assembly in aqueous solutions and cell culture media, antiradical activity, UV cytoprotective action, and antiviral activity against international reference strains of influenza virus A(H1N1)pdm09, A(H3N2), and B subtypes in vitro on the MDCK cell line. Various characterization techniques, including Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, NMR and ESR spectrometry, MALDI-TOF mass spectrometry, thermal analysis (TGA and DSC), dynamic light-scattering (DLS), and ζ-potential measurements, were used to confirm the production of fullerenol and study its self-assembly in aqueous solutions and cell culture media. Fullerenol C60(OH)36 demonstrated the ability to scavenge •DPPH, •OH, O2•− radicals and 1O2 and was non-toxic in the range of the studied concentrations (up to 200 μg/mL) when incubated with MDCK cells for 24 h. In addition, fullerenol exhibited a cytoprotective effect under UV irradiation (EC50 = 29.7 ± 1.0 μM) and showed moderate activity against human influenza viruses of subtypes A(H1N1)pdm09 (SI = 9.9 ± 4.6) and A(H3N2) (SI = 12.5 ± 1.3) when determined by the hemagglutination assay (HA-test) and the MTT assay. At the same time, C60(OH)36 was ineffective in vitro against the actual strain of influenza B virus (Victoria lineage). The high bioavailability of fullerenol in combination with its cytoprotective effect, as well as its antiradical and antiviral activity combined with a relatively low toxicity, allows to consider it a promising compound for biomedical applications.

Huntington's disease (HD) is one of the human neurodegenerative diseases for which there is no effective treatment. Therefore, there is a strong demand for a novel neuroprotective agent that can alleviate its course. Fullerene derivatives are considered to be such agents; however, they need to be comprehensively investigated in model organisms. In this work, neuroprotective activity of C60(OH)30 and C120O(OH)44 fullerenols was analyzed for the first time in a Drosophila transgenic model of HD. Lifespan, behavior, oxidative stress level and age-related neurodegeneration were assessed in flies with the pathogenic Huntingtin protein expression in nerve cells. Feed supplementation with hydroxylated C60 fullerene and C120O dimer oxide molecules was shown to diminish the oxidative stress level and neurodegenerative processes in the flies' brains. Thus, fullerenes displayed neuroprotective activity in this model.

A mixture of iron carbides and fullerene C 60 formed by electric arc synthesis has been hydroxylated by adding OH groups to the fullerene surface, which made it possible, according to the EXAFS data, to obtain almost pure fullerenol Fe@C 60 (OH) 30 . Powder samples of the fullerenol and the product obtained after its dehydroxylation have been examined using Mössbauer spectroscopy. The Mössbauer spectra have been processed under the assumption of superposition of three partial doublets of spectral lines. It is established that two doublets due to Fe 3+ dominate in the fullerenol spectrum. For the reduced fullerene Fe@C 60 sample, two doublets are due to Fe 3+ and the Fe 2+ doublet dominates. Thus, attachment of OH groups from the outer side of the fullerene carbon frame increases the oxidation state of iron, which shows that the iron atom is located inside the frame.

A procedure was suggested for highly efficient extraction of fullerenes from electric arc carbon black, with the degree of recovery reaching 86% of the carbon black weight. Analysis by HPLC and by IR and Raman spectroscopy shows that the extracts obtained consist of a mixture of fullerenes. The possibility of preparing highly water-soluble fullerene derivatives from the extracts by hydroxylation with an aqueous solution of hydrogen peroxide was demonstrated.

The radiation resistances of fullerenes C-60 and C-70, end metallofullerenes Me@C(2)n (n = 30 - 50), derivatives C-60(OH)((30)) and Me@C-2n(OH)(30-40) (Me = Sm, Eu, Gd, Tb, Ho, Fe, Co), and complexes with biocompatible polymers - polyvinylpyrrolidone and dextrin - Fe@C-60(C6H9NO)(n), Sm@C-82(C6H9NO)(n), Gd@C-82(C6H9NO)(n) and Fe@C-60(C6H10O5)(n) were studied. For the structures irradiated by protons with energies of 100 MeV and 1 GeV, radiation resistance was estimated. The comparison of the results of radiation resistance under irradiation by protons and reactor neutrons at fluencies from 10(18) to 10(19) cm(-2) was carried out. It is shown, that endofullerenols are more stable under the proton and neutron irradiation than initial endofullerenes. The molecules containing Eu, Gd and Sm with large thermal neutron capture cross sections were found to be the most stable under neutron irradiation. The mechanism of rebuilding of secondary endofullerenols Eu, Sm, Gd, as well as other factors' influence on radiation resistance are discussed.

The toxicity of C60(OH)30, C70(OH)30, and C120O(OH)n fullerenols, prepared by a new original method, has been studied. This method allowed us to obtain high-purity fullerenols and eliminate the risks of synthesis of preparations containing insoluble fractions contaminated with impurities such as fullerenes not completely reacted by hydroxylation. All fullerenols were detected inside cultured cells. The MTT assay as well as the analysis of apoptosis and cell cycle showed that С60(ОН)30 and С70(OH)30 are non-toxic for cultured V79 и HeLa cells at concentrations exceeding physiological levels by an order of magnitude. С120O(OH)n caused low toxicity. Studies in Drosophila melanogaster showed that any preparations used did not result in a decreased lifespan or in behavior abnormalities in flies.