Selective accumulation of rare earth metal and heavy metal ions by a DNA-inorganic hybrid material

Abstract

A DNA-inorganic hybrid film (DNA film) was prepared by mixing DNA and a silane coupling reagent, bis(trimethoxysilylpropyl)amine. This DNA film can accumulate heavy metal ions in aqueous solution. We have demonstrated the accumulation of rare earth metal and heavy metal ions using DNA-inorganic hybrid-immobilized glass beads (DNA beads), which were prepared by coating the DNA-inorganic hybrid onto glass beads. When these DNA beads were placed in an aqueous solution of metal ions and incubated for 24 h (batch method), the DNA beads selectively accumulated heavy metal and rare earth metal ions. The maximum-accumulated amounts of Cu2+, Cd2+, In3+ and La3+ were ∼1.2, 0.94, 1.6 and 1.3 μmol, respectively, for 1 mg of DNA (3.0 μmol of nucleotide). The molar ratio of DNA to a metal ion was nucleotide:metal ion=1:0.5. Finally, we demonstrated the accumulation of metal ions by a DNA-bead column (DNA column). As a result, the DNA column effectively accumulated the heavy metal and rare earth metal ions. The DNA column was recycled by washing with an EDTA solution. DNA-immobilized glass beads (DNA beads) were prepared by coating DNA-inorganic hybrid material onto glass beads. When these DNA beads were placed in an aqueous metal ion-containing solution and incubated (batch method), the DNA beads selectively accumulated the heavy and rare-metal ions, such as Cu2+, Cd2+, In3+ or La3+. Therefore, we demonstrated the accumulation of metal ions by a DNA-immobilized glass bead column (DNA column). As a result, the DNA column effectively accumulated the heavy and rare-metal ions. Furthermore, the DNA column could be recycled by washing it with an aqueous EDTA solution.