C_(60)/Cu^(2+)影响质粒DNA构象的复合效应研究

Combined Effect Study of C_(60)/Cu^(2+) Affecting Plasmid DNA Conformation

碳纳米材料的毒性效应日益受到广泛关注,通过比较研究多种非光催化条件下,富勒烯(C60)/Cu2+共存时对质粒DNA构象影响的复合作用,借以评估碳纳米材料的毒性效应。实验结果显示在非光催化条件下,C60/Cu2+可显著诱导DNA构象从超螺旋DNA转变成开环DNA,并且这种剪切效应随C60和Cu2+浓度的升高而增强;断裂后的DNA片段可重新被T4DNA连接酶连接成环状DNA,这说明C60/Cu2+的剪切位点为磷酸二酯键。另外,多种活性氧捕获剂均不能有效消除C60/Cu2+对DNA的剪切作用,这与Cu2+在DNA裂解中起主要作用相关。上述研究结果表明在非光催化条件下,C60/Cu2+可有效诱导DNA断裂,具有明显的复合效应,其潜在的基因毒性值得关注。

The toxic effects of carbon nanoparticles have been increasingly gaining attention. In this research, the combined effect of C60/Cu2＋ on DNA conformation was comparatively studied by altering various reaction conditions, to assess the biological toxicity of carbon nanoparticles. The results showed that without photoexeitation, C60/Cu2＋ could significantly induce the conversion of supercoiled DNA into nicked DNA, and this DNA cleavage effect was enhanced as the concentration of Cu2＋ and C60 increased. Moreover, the cleaved DNA could be reconnected to circular DNA by T4 DNA ligase, which indicated that the phosphodiester bond was the splicing site of C60/Cu2＋. In addition, various ROS savengers could not reduce the DNA cleavage effect of C60/ Cu2＋, which was relate to the feature that Cu2＋ played a pivotal role in DNA cleavage. Taken to- gether, these results demonstrated that Ca/Cu2＋ could significantly induce the DNA cleavage with- out photoexcitation, which exhibited obvious combined effect. Further consideration should be given in assessment of their potential genotoxicity.