A study of double stranded DNA adsorption on aluminum surface by means of electrochemical impedance spectroscopy

Immobilization of DNA on the solid surfaces is one of the goals in bio- and nano-technologies. Adsorption of double stranded DNA on the surface of aluminum was electrochemically studied by means of impedance spectroscopy. Nyquist diagram of aluminum in a tris (hydroxymethyl) ammoniummethane–HCl (Tris–HCl) buffer solution, pH 7.4 consisted of two overlapped capacitive semicircles. The high-frequency semicircle was related to the passivity of Cl−-containing aluminum species in the oxide layer, and low-frequency semicircle was attributed to metal dissolution. When DNA was added to the Tris–HCl buffer solution, Nyquist diagrams represented an inductive loop at low frequencies due to the adsorption of DNA on the pre-covered aluminum surface by hydroxy-contained species. The DNA adsorption on the aluminum surface was also confirmed by X-ray photoelectron spectroscopy. Open circuit potential variation with time also indicated the chemical adsorption of DNA on the aluminum surface.