Technologies for the accumulation of noble and rare-earth elements have attracted significant attention in the past decade owing to their increasing industrial demand. Chitosan, as well as other compounds with relatively high amine functional group content, have already been shown to be efficient, inexpensive, and environmentally friendly adsorbents of these valuable metals. [1] Complexation of DNA with many metal ions is also well known [2] and the high affinity of DNA phosphates for various rare-metal ions was demonstrated in recent reports by Takahashi et al. [3] Although originally only the biological aspect of DNA was intensively investigated, many studies focused on the application of DNA as a functional material. [4] For example, we [5] and others [6] have successfully demonstrated the application of DNA for the extraction of hazardous metal ions and organic contaminants from aqueous solutions. Similarly, the application of DNA for the extraction of noble and rare-metal ions can be considered. However, owing to the high colloidal stability of DNA in aqueous solution, either deposition of DNA on a suitable solid substrate (e.g., inorganic micro-beads used in columns [6b] ) or post-treatment of DNA complexes with condensation chemicals to induce DNA phase separation from the aqueous phase, [5a] are required.Herein, we propose a single-step extraction of noble-metal (Au, Pd) and rare-earth (Yb) ions from aqueous solutions by using a DNA hydrogel, which possesses intrinsic DNA affinity to the metal ions. The DNA hydrogel was prepared according to a modified procedure reported by Tanaka and Amiya, [7] who studied DNA hydrogels in relation to phase transition in lowpolar solvents. DNA is a suitable natural polymer for the collection of metal ions because the amine and phosphate groups of DNA can act as chelating sites for metal ions.Typically, the sodium salt of DNA from salmon milt (0.1 g) was mixed with MilliQ water (400 mL) and a 1 m aqueous solution of NaOH (320 mL, final solution pH 13-14), and crosslinked by the addition of ethylene glycol diglycidyl ether (EGDE; 50 mL) at room temperature during 2 hours of incubation. Cross-linking occurs through the reaction between amino groups of the DNA nitrous bases and epoxy groups of EDGE, as shown in Scheme 1. [8] The resulting hydrogel was transferred into MilliQ water (200 mL) and incubated for 24 hours to remove unreacted EGDE, NaOH, and non-cross-linked DNA. The hydrogel was then equilibrated against MilliQ water (300 mL) twice in 24 hours. The resulting hydrogel contained 1.5 mm DNA (DNA phosphates per hydrogel volume), as determined by UV spectroscopy measurements of the DNA hydrogel after ultrasonic homogenization for 5 minutes.In all extraction experiments, the same amount of DNA was used, that is, 2.5 g of DNA hydrogel with a DNA concentration Scheme 1. Cross-linking reaction between two DNA nucleotides and EDGE.