Accumulation-Exclusion Combined System for the DNA-Binding Harmful Chemicals with Insolubilized DNA

Abstract

DNA is not only the most important genetic material but a highly functional biomaterial. The unique structure of the double-stranded DNA causes its highly specific functions, such as intercalation, groove-binding and other molecular recognitions. Previously, we reported the preparation of insolubilized DNA by UV-irradiation. The UV-irradiated DNA showed the potential utility as an accumulation device for harmful DNA-binding chemicals such as the dioxin-derivative. In this study, we investigated the exclusion process of accumulated chemicals from the insolubilized DNA, and extended this approach to the construction of an accumulation-exclusion combined system for DNA-binding harmful chemicals. Such a system would allow us to systematically concentrate very small amount of DNA-binding chemicals from large amounts of water. It might provide a suitable method to omit the complicated pre-treatment processes which are popular in the analysis for the highly diluted chemicals in the water system such as some environmental hormones. Two different procedures were performed to exclude ethidium bromide (EtBr) from UV-irradiated DNA containing EtBr. The first one is the treatment with a cationic polymer which would induce DNA-condensation and, as a result, exclude EtBr. Another one is the extraction of EtBr with organic solvent. The extraction process with an organic solvent attained a high exclusion efficiency for EtBr. The UV-irradiated DNA which accumulated the EtBr, could be easily recovered by washing with some organic solvents and maintain the efficiency to accumulate the DNA-binding chemicals.