The Ni 2+/poly（o-aminophenol）electropolymerization was carried out by a continuous cyclic voltammetric scanning at a carbon paste electrode in a mixture of 0.02 mol/L o-aminophenol,0.3 mol/L NiSO 4 and 0.6 mol/L HClO 4.dsDNA was linked to the conducting polymer via three-dimensional structure of polymer film and electrostatic attraction between the negatively charged phosphate backbone of DNA and Ni 2+ ion.The results were testified by the electrochemical methods by using Co（phen）2+3 as an electrochemical indicator.The currents of redox peaks of Co（phen）2+3 increased after immobilizing dsDNA.The conditions for the preparation of Ni 2+/P-OAP/CPE and DNA immobilization were optimized.The voltammetric behavior of dopamine was investigated at the modified electrode.It was found that the modified electrode exhibited a highly electrocatalytic activity toward dopamine oxidation.Differential pulse voltammetry was used for determination of dopamine in pH 5.1 phosphate buffer solution.A linear response of the peak current versus the concentration was found in the range from 5.0×10-6 to 2.0×10-4mol/L with 1.0×10-2 mol/L AA（ascorbic acid）coexisting.The presence of a high concentration of AA did not interfere with the determination.The proposed method exhibits a good recovery and reproducibility.
