In this work, a sensitive electrochemical DNA biosensor for the detection of sequence-specific target DNA was reported. Firstly, CuO nanospindles （CuO NS） were immobilized on the surface of a glassy carbon electrode （GCE）. Subsequently, gold nanoparticles （Au NPs） were introduced to the surface of CuO NS by the electrochemical deposition mode. Probe DNA with SH （HS-DNA） at the 5＇-phosphate end was covalently immobilized on the surface of the Au NPs through Au-S bond. Scanning electron microscopy （SEM） was used to elucidate the morphology of the assembled film, and electrochemical impedance spectroscopy technique （EIS） was used to investigate the DNA sensor assembly process. Hybridization detection of DNA was performed with differential pulse voltammetry （DPV） and the methylene blue （MB） was hybridization indicator. Under the optimal conditions, the decline of reduction peak current of MB （A/） was linear with the logarithm of the concentration of complementary DNA from 1.0 X 10-13 to 1.0× 10-6 mol·L l with a detection limit of 3.5 × 10 14 mol·L -1 （S/N=3）. In addition, this DNA biosensor has good selectivity, and even can distinguish single-mismatched target DNA.
