Effect of polymer carrier origin and physical state on fullerene C60 phototoxicity in vitro

Biological effects of water-soluble inclusion complexes of fullerene C60 with poly(vinyl pyrrolidone) (C60/PVP) and gamma-cyclodextrin (C60/g-CD) as well as solid C60 (C60-coated surface) on cell viability have been studied in vitro. It is established that both inclusion complexes (in a broad range of concentrations) and solid fullerene coatings are nontoxic in the dark for the cell of all lines tested. In contrast, under intense UV illumination, the C60/PVP complex reliably protected test cells from the UV radiation damage, whereas the C60/g-CD and fullerene-coated surface exhibited pronounced phototoxicity. Moreover, solid fullerene caused a photodynamic effect under irradiation with both UV and visible light. The radiation damage could be blocked by some antioxidants (e.g., hypoxen) and singlet-oxygen scavenger (sodium azide). This is evidence for the participation of 1O2 in phototoxicity manifestations. The results indicate that the biological properties of fullerene C60 in vitro depend on its aggregate state, form of solubilization, and, probably, the nature of solubilizing medium.