UV-Irradiated DNA Matrix Selectively Accumulates Heavy Metal Ions

We recently demonstrated the preparation of a water-insoluble DNA matrix by UV irradiation. The UV-irradiated DNA matrix selectively accumulated DNA-intercalating compounds and some endocrine disruptors. We evaluated the accumulation of metal ions in the UV-irradiated DNA matrix using a UV-irradiated DNA-film and DNA-immobilized glass beads. When DNA-immobilized glass beads were incubated with an aqueous solution of Hg2+, Cd2+, Pb2+, Zn2+, Cu2+, or Fe3+, the heavy metal ions were accumulated in the DNA-beads. The maximum amounts of the accumulated Hg2+, Cd2+, and Cu2+ in the DNA-beads were approximately 0.21, 0.13, and 0.22 mmol per gram of immobilized-DNA, respectively. The amounts of the accumulated Pb2+, Zn2+, and Fe3+ were lower than that of Hg2+, Cd2+, and Cu2+. Further, Fourier transform infrared (IR) studies using a UV-irradiated DNA-film with heavy metals suggested that the heavy metal ions interacted with not only the nucleic acid bases but also the phosphate groups. In contrast, the DNA-immobilized glass beads could not accumulate Ca2+ and Mg2+. These results suggested that the UV-irradiated DNA could selectively accumulate metal ions. The UV-irradiated DNA matrix has potential utility as a functional material to remove harmful heavy metal ions from contaminated water.