Toxicity of the C₆₀ fullerene aqueous colloid solution in vitro and in vivo experiments was studied. C₆₀ fullerene in the concentration range of 3.6-144 µg/mL demonstrated low toxicity against human embryonic kidney (HEK293) cells with 383.4 μg/mL IC₅₀ value. The acute toxicity of C₆₀ fullerene in a dose progression (75, 150, 300, 600, 1200 and 1800 mg/kg) was investigated at 14^th day after single intraperitoneal (i.p.) administration into mice. No toxic effect of С₆₀ fullerene in the dose range of 75-150 mg/kg was observed; the calculated LD₅₀ value was 721 mg/kg. The toxic effect of C₆₀ fullerene was observed at a concentration of 300 mg/kg and higher, it was accompanied with mice behavior disturbance, hematotoxicity and pathomorphological changes in spleen, hepatic and kidney tissues. In mice treated with 600 mg/kg of C₆₀ fullerene indices of inflammatory process were detected, whereas at 1200 mg/kg dose leukopoies and thrombocytopoies were found to be suppressed. Thus, C₆₀ fullerene aqueous colloid solution in a dose range of 75-150 mg/kg is nontoxic and could be used for biomedical purposes.

Development of nanocarriers for effective drug delivery to molecular targets in tumor cells is a real problem in modern pharmaceutical chemistry. In the present work we used pristine C₆₀ fullerene as a platform for delivery of anticancer drug doxorubicin (Dox) to its biological targets. The formation of a complex of C₆₀ fullerene with Dox (C₆₀ + Dox) is described and physico–chemical characteristics of such complex are presented. It was found that Dox conjugation with C₆₀ fullerene leads to 1.5-2-fold increase in Dox toxicity towards various human tumor cell lines, compared with such effect when the drug is used alone. Cytotoxic activity of C₆₀ + Dox complex is accompanied by an increased level of cell produced hydrogen peroxide at early time point (3 h) after its addition to cultured cells. At the same time, cellular production of superoxide radicals does not change in comparison with the effect of Dox alone. Cytomorphological studies have demonstrated that C₆₀ + Dox complexes kill tumor cells by apoptosis induction. The results of in vivo experiments using Lewis lung carcinoma in mice confirmed the enhancement of the Dox toxicity towards tumor cells after drug complexation with C₆₀ fullerene. The effect of such complex towards tumor-bearing mice was even more pronounced than that in the in vitro experiment with targeting human tumor cells. The tumor volume decreased by 2.5 times compared with the control, and an average life span of treated animals increased by 63% compared with control. The obtained results suggest a great perspective of application of C₆₀ + Dox complexes for chemotherapy of malignant tumors.

Background Doxorubicin (Dox) is one of the most potent anticancer drugs, but its successful use is hampered by high toxicity caused mainly by generation of reactive oxygen species. One approach to protect against Dox-dependent chemical insult is combined use of the cytostatic drug with antioxidants. C₆₀ fullerene has a nanostructure with both antioxidant and antitumor potential and may be useful in modulating cell responses to Dox. Objective The aim of this study was to estimate the antitumor effect and antioxidant enzyme activity of combined C₆₀ fullerene and Dox (C₆₀ + Dox) in the liver and heart of mice with Lewis lung carcinoma compared with Dox treatment alone. Methods Highly stable pristine C₆₀ fullerene aqueous colloid solution (concentration 1.0 mg/ml, average hydrodynamic diameter of nanoparticles 50 nm) was used in the study and characterized by means of atomic force microscopy (AFM). The in vivo investigation of C₆₀-Dox action was performed via the standard methods of histological and enzyme activity analyses. Results Dox (total dose 2.5 mg/kg) combined with C₆₀ fullerene (total dose 25 mg/kg) in tumor-bearing animals resulted in tumor growth inhibition, prolongation of life, metastasis inhibition, and increased number of apoptotic tumor cells and was more effective than the corresponding course of Dox treatment alone. C₆₀ fullerene demonstrated a protective effect against superoxide dismutase and glutathione peroxidase inhibition induced by Dox-dependent oxidative insult in the liver and heart. Conclusion Combined treatment with C₆₀ + Dox is considered to be a promising approach for cancer chemotherapy.

We formulated and analyzed a novel nanoformulation of the anticancer drug cisplatin (Cis) with C₆₀ fullerene (C₆₀+Cis complex) and showed its higher toxicity toward tumor cell lines in vitro when compared to Cis alone. The highest toxicity of the complex was observed in HL-60/adr and HL-60/vinc chemotherapy-resistant human leukemia cell sublines (resistant to Adriamycin and Vinculin, respectively). We discovered that the action of the C₆₀+Cis complex is associated with overcoming the drug resistance of the tumor cell lines through observing an increased number of apoptotic cells in the Annexin V/PI assay. Moreover, in vivo assays with Lewis lung carcinoma (LLC) C57BL/6J male mice showed that the C₆₀+Cis complex increases tumor growth inhibition, when compared to Cis or C₆₀ fullerenes alone. Simultaneously, we conducted a molecular docking study and performed an Ames test. Molecular docking specifies the capability of a C₆₀ fullerene to form van der Waals interactions with potential binding sites on P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP-1), and multidrug resistance protein 2 (MRP-2) molecules. The observed phenomenon revealed a possible mechanism to bypass tumor cell drug resistance by the C₆₀+Cis complex. Additionally, the results of the Ames test show that the formation of such a complex diminishes the Cis mutagenic activity and may reduce the probability of secondary neoplasm formation. In conclusion, the C₆₀+Cis complex effectively induced tumor cell death in vitro and inhibited tumor growth in vivo, overcoming drug resistance likely by the potential of the C₆₀ fullerene to interact with P-gp, MRP-1, and MRP-2 molecules. Thus, the C₆₀+Cis complex might be a potential novel chemotherapy modification.

The aim of the present work was the investigation of the interaction of water-soluble pristine fullerenes C₆₀ with bimolecular lipid model membrane (BLM) and cellular plasma membrane (PM). The findings demonstrate that the fullerenes C₆₀ at low concentrations, namely in the concentration range of 1.0 × 10⁻⁴–1.0 mg·ml⁻¹, are preferentially incorporated into the hydrophobic region of BLM, increasing, thus, its specific conductivity and specific capacity. Furthermore, upon interaction of fullerenes C₆₀ with PM, pores or other type of local defects are formed, which are wide enough in order to permit the passage of water molecules across the cell membrane resulting to the externalization of phosphatidylserine from the inner to the outer PM leaflet.

Fullerene C60 as a representative of carbon nanocompounds is suggested to be promising agent for application in photodynamic therapy due to its unique phys