Preparation and voltammetric characterization of DNA modified electrode with ethylenediamine as arm molecule

Carboxyl was formed on the surface of glassy carbon electrode(GCE) by electrochemical oxidation. Ethylenediamine(En) was used as the arm molecule to link carboxyl with dsDNA using 1-ethyl-3(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide(NHS) as the activators to prepare dsDNA modified electrode (dsDNA/En/GCE). It was shown that dsDNA could be covalently immobilized on the surface of GCE. ssDNA modified electrode (ssDNA/En/GCE) was obtained via the thermal denaturation of dsDNA/En/GCE. The dsDNA/En/GCE and ssDNA/En/GCE were characterized by voltammetry with methylene blue(MB) as the indicator. The results indicated that the currents of the redox peaks of MB at ssDNA/En/GCE were larger than those at dsDNA/En/GCE, and the currents of the redox peaks at En/GCE were the smallest. The peak-currents of MB at the DNA modified electrode had good reproducibility after multi-denaturation and hybridization cycles.