Abstract: DNA modified electrode was prepared by covalent immobilization of ssDNA or dsDNA on a mercaptoethanol monolayer self-assembled gold electrode with the help of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimidehydrochloride (EDC) and N-hydroxysuccinimide (NHS). The electrochemical behaviors of brilliant cresyl blue (BCB) on ssDNA or dsDNA electrodes were studied. BCB had different binding models with ssDNA or dsDNA and the adsorptive constants were 1.67×10^4 L·mol-1 for ssDNA/Au electrode and 3.22×10^4 L·mol-1 for dsDNA/Au electrode. BCB bound to ssDNA via electrostatic interaction while bound to dsDNA through both the electrostatic and intercalative models. The results showed that dsDNA had a stronger appetency for BCB, which indicated that BCB was a suitable electroactive indicator.

Key words: Mercaptoethanol, DNA, Self-assembled monolayer, Gold electrode, Electrochemistry, Brilliant cresyl blue