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.