Abstract:

The self-assembling， hybridization and orientation of SH-ssDNA on the surface of thin-film nano-gold electrodes were characterized systematically by means of the electrochemical impedance technique. The effects of assembling time, concentration and the length of SH-ssDNA on its self-assembling were investigated. The Rct and surface coverage reached the highest values when assembling time was 15 h. The influences of the concentration and length of SH-ssDNA and its hybridization method with complementary DNA on the hybridization reaction were also studied. The result shows the change of R_ct decreases with the increase of the SH-ssDNA concentration. The R_ct was increased by 16% when the concentration of SH-ssDNA was 5 μmol/L. The data simulation and analysis of impedance spectroscopy indicated that a unique self-assembled monolayer of SH-ssDNA was formed with an upright orientation on the nano-Au electrode surface. The result shows the hybridization efficiency is closely associated with the coverage of SH-ssDNA.

Key words: Electrochemical Impedance Spectroscopy, SH-ssDNA, Self-Assembling, Hybridization, Orientation