For this process, 4 L of the DNA aptamer (9.6 M HS-DNA)
was placed on a previously conditioned Au electrode that was held
upside down, and the end of the electrode was fitted with a plastic
cup to protect the solution from evaporation. The assembly was
kept standing for 3.0 h at room temperature. After rinsing, the modified
electrode was treated with 1.0 mM 6-mercapto-1-hexanol
(MCH) solution for 1 h to mask the unmodified Au sites