Study On DNA Damage Mechanism And Toxicity Effects Of Fullerene

The toxicity of nano-particle has been concerned widely and increasely. In this work, The DNA damage and the in vitro toxic effects caused by C₆₀ was studied. We discuss the interaction between C₆₀ and organism, further the method on researching nano-particle toxicity and the toxicity of some nano-particle were studied.In this study, we found that C₆₀ can degrade pBR322 plasmid DNA under normal temperature without photo activation, which was correlated to the incubation temperature, reaction time and concentration of C₆₀. The generation of superoxide radical anion in the solution detected by chemical method was also related to the incubation temperature, reaction time and the concentration of C₆₀. Superoxide dismutase acts as a kind of ROS scavenger and inhibited DNA cleavage and O₂^- generation induced by C₆₀. These results indicated that the ROS induced by non-photo treated C₆₀ under normal temperatures should be the major cause of DNA cleavage. Also, when formamide or other acylamidocyanogen group-containing organic compound was co-incubated with C₆₀, the DNA degradation induced by C₆₀ was significantly inhibited. Moreover, while increasing the ionic strength of the reaction solution, the degradation was eliminated as well, suggesting that DNA conformation stability and C₆₀ surface characters are the others important factors in DNA degradation. SYBR GREEN I Combination assay demonstrated that C₆₀ might bind to DNA and affect its conformation. Based on the above results, we conclude that C₆₀ may bind to DNA, decrease DNA conformation stability, induce ROS generation and degrade DNA strand at normal temperatures.In order to simulate the course of DNA replication, PCR reaction as the research model which was based on a designed single strand DNA template was established to evaluate the effect of C₆₀ on DNA in vitro replication and the potential genotoxicity. The agarose gel staining results showed that C₆₀ could dose-dependently inhibit the generation of PCR products; After co-incubated with C₆₀, the activity of Taq DNA polymerase was significantly inhibited; The amplification product of treated DNA template was decreased also; The inhibition effect induced by C₆₀ could be eliminated by increasing the amount of Taq DNA polymerase in the PCR reaction solution, but could not be eliminated by increasing the quantity of DNA template. The results revealed that C₆₀ could inhibit the activity of Taq DNA polymerase, and should have potential adverse effect on DNA template.The cytotoxicity results indicated that the water-soluble C₆₀ had no obvious effects on the viability of human gastric cancer cell line SGC-7901 and human embryonic kidney cell line HEK-293, as well as the expression of the CYP1A1.Escherichia coli, bacillus subtilis and pseudomonas aeruginosa were exposed to C₆₀. Results revealed that the growth of these three bacteria were inhibited by C₆₀ with obvious time and dose-response effect. Different from pseudomonas aeruginosa, escherichia coli and bacillus subtili could recover into normal state after exposing to C₆₀, that was quite related to the endurance ability and the mechanism of antibacteria.