Preparation of DNA-immobilized magnetic particles and their utilization as an accumulative material of metal ions

Abstract

DNA-immobilized Fe 3 O 4 particles (DNA-Fe-particles) were prepared by mixing DNA, magnetic Fe 3 O 4 particles, and the silane coupling reagent, bis [3-(trimethoxysilyl)propyl]amine. The DNA-inorganic hybrid material was uniformly immobilized onto magnetic Fe 3 O 4 particles with the diameters of approximately 450 nm. These DNA-Fe-particles were stable in water. Additionally, we could simply collect the DNA-Fe-particles by a magnet from an aqueous solution. Therefore, we demonstrated the accumulation of various metal ions, such as heavy and rare-earth metal ions, by the DNA-Fe-particles. As a result, although these DNA-Fe-particles could selectively accumulate heavy and rare-earth metal ions, these materials could not accumulate the light metal ions, such as Mg(II) and Ca(II) ions. Furthermore, the metal ion-accumulated DNA-Fe-particles could be recycled by washing them with an aqueous ethylenediaminetetraacetic acid solution.

Preparation of water‐insoluble and biochemically stable RNA hybrid material

“…These phenomena suggested that the nucleic acid base in RNA interacts with the ―NH― group in the imino group of SiNSi through hydrogen bonding. On the other hand, when the SiNSi molecules were added to the RNA materials, the absorption band at 1203 cm −1 , which is related to the phosphate group, did not change. These results indicated that the SiNSi molecules did not interact with the phosphate group of RNA.…”

“…Figure shows the IR spectra of (A) RNA without the hybridization, (B) RNA‐10 wt% SiNSi hybrid, (C) RNA‐20 wt% SiNSi hybrid, (D) RNA‐30 wt% SiNSi hybrid, (E) RNA‐50 wt% SiNSi hybrid, (F), RNA‐70 wt% SiNSi hybrid, and (G) dried SiNSi materials. The RNA material indicated absorption bands at 1676, 1635, and 1203 cm −1 , related to the stretching vibration of C═O in the nucleic acid base, the stretching vibration of C═N in the nucleic acid base, and the antisymmetric stretching vibration of the phosphate group, respectively . The intensity ratio of the absorption bands at 1676 cm −1 and 1635 cm −1 changed by the addition of the SiNSi molecules.…”

“…The initial concentration of Cu(II) ion was 20 ppm, and the amount of RNA in the hybrid material was 1.6 mg. The accumulated amount of Cu(II) ions was estimated from the calibration curve with the metal indicator XO . The accumulated amount of Cu(II) ions increased with the incubation time and reached a constant value at 6 hours.…”

“…The accumulated amount of metal ion was determined from the absorbance of the aqueous solutions in the absence or presence of the RNA‐SiNSi hybrid film. The concentration of metal ion was estimated from the calibration curve using the metal indicator XO, methylthymol blue, or 4‐(2‐pyridylazo)resorcinol …”

“…Therefore, the double‐stranded DNA can be used as a biomedical, pharmaceutical, and engineering materials . Recently, we reported the selective accumulation of a planar‐structure containing harmful compounds by the intercalation function of the double‐stranded DNA and the effective accumulation of rare‐earth metal ions by the binding to nucleic acid bases . As a result, we propose the novel utilization of the double‐stranded DNA for environmental applications, such as an absorbent of harmful compounds and useful components …”