Electrostatic trapping of double-stranded DNA by using cadmium hydroxide nanostrands.

Cadmium ions (Cd(2+)) spontaneously grew into cadmium hydroxide nanostrands at the proper pH range in water, and the nanostrands efficiently captured negatively charged DNA. The DNA chain adsorbed parallel to the nanostrand due to the numerous positive charges on the extremely long and thin structure of 1.9 nm, giving weakly gelled white precipitates. By the filtration, more than 95% of DNA was separated from the dilute solution with a concentration less than 40 ng/mL. The nanostrands quickly disappeared after adding aqueous EDTA, and DNA was released quantitatively. These characteristics gave a novel separation technique for short DNA fragments without the use of organic solvents.