Selection of a nickel-specific DNA aptamer and development of a protocol for radioactive nickel removal

Abstract

Development of technology for removal of radioactive particles including nickel from liquid nuclear waste is necessary for maintenance of nuclear power plants. In this study, we focused on development of a method for trapping radioactive nickel ions using an aptamer capable of capturing small molecules such as metal ions. Nine rounds of SELEX were performed resulting in selection of two aptamers with high affinity for nickel. Liquid containing 3 nmol stable nickel was passed through a column containing aptamer/bead, and a reduction in the concentration of nickel of 95% or more in the liquid passed through column was confirmed by measurement using ICP-OES. Based on the interaction between the FA-N1 aptamer-bead composite and the nickel-containing surrogates, the specificity for nickel was at least three times higher than that for other metal ions such as cobalt and chrome. Examination of the interaction of the aptamer with stable nickel, a non-radioactive isotope, and nickel-63, a radioactive isotope, was performed in order to determine whether it has similar specificity for radioactive and non-radioactive metal ions. In addition, because recovery of more than 99.5% of nickel bound to the aptamer/bead complex was achieved, the aptamer could be reused. Based on these results, we predict that the aptamer, which is capable of removing radioactive nickel through capture of radioactive isotopes of nickel, can be utilized effectively in the effort to reduce liquid nuclear waste.