Contributions of phosphate to DNA adsorption/desorption behaviors on aminosilane-modified magnetic nanoparticles.

The adsorption and desorption behaviors of DNA on aminosilane-modified magnetic nanoparticles were investigated by altering both type of anions and solvation state to achieve eficient recovery of DNA useful for subsequent polymerase chain reaction (PCR) analysis. The effects of multiple anions in accordance with the Hofmeister ion series were determined to clarify the contribution of phosphate ions on the effective desorption of DNA from aminosilane surfaces. Efficient DNA desorption (85% recovery) occurred in the presence of 1 M phosphate buffer, however, little DNA desorption was observed using any other anions. This phenomenon indicates that desorption originated from the replacement of DNA by phosphate ions. Furthermore, the adsorption and desorption were significantly affected by the addition of both protic and aprotic solvents. Efficient recovery of adsorbed DNA was attained using deoxynucleotide triphosphates (dNTPs) in place of phosphate buffer and was suitable for subsequent PCR analyses. Therefore, the DNA adsorption/desorption process proposed in this study will be a promising, novel approach for DNA purification with a high recovery ratio that is suitable for subsequent enzymatic reactions, such as PCR or restriction enzyme digestion.