Induced temperature-dependent DNA degradation by C60 without photoactivation

This study shows that C₆₀ can degrade pBR322 plasmid DNA at room temperature without photoactivation. The degradation was enhanced by increasing incubation temperature, reaction time or C₆₀ concentration. We also found that superoxide radical anions (O ₂ ^?· ) were formed in the C₆₀ solution. Superoxide dismutase significantly inhibited DNA cleavage and O ₂ ^?· generation induced by C₆₀. These results suggest that DNA cleavage was caused by the formation of reactive oxygen species induced by C₆₀ at room temperature. Furthermore, we demonstrate that the DNA degradation was significantly inhibited by acid amide chemicals such as formamide, and by increased ionic strength of the reaction solution. These results indicate that the DNA conformation stability and the surface properties of C₆₀ are important factors regulating DNA degradation. We propose that C₆₀ can bind DNA, decrease DNA conformation stability, and induce the formation of reactive oxygen species and DNA cleavage at room temperature. Our results provide a possible explanation for the genotoxicity of C₆₀, which should be considered in future use of this particular nano-material.