Electrochemical Behaviors of Methylene Blue on DNA Modified Gold Electrode

DNA modified electrode was prepared by covalent immobilization of single-stranded calf thymus DNA (ssDNA) or double-stranded calf thymus DNA (dsDNA) on a mercaptoethanol monolayer self-assembled gold electrode with the help of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The electrochemical behaviors of methylene blue (MB) on ssDNA/self-assembled monolayer (SAM)/Au or dsDNA/SAM/Au electrodes were studied. MB binds to ssDNA or dsDNA with different models. The adsorptive constants are larger for dsDNA/SAM/Au electrode than ssDNA/SAM/Au electrode. MB binds to dsDNA predominantly intercalative models. The results show that dsDNA had a stronger appetency for MB, which indicates that MB is a suitable hybridization indicator.