Abstract: Thionine was firstly electropolymerized on the glassy carbon electrode (GCD) surface,and then prussian blue-gold nanocomposites (PB-Au) and gold nanoparticals (GN) were electrodeposited on modified electrode surface respectively.Finally,DNA probes (ssDNA) were conjugated with GN through Au-NH2 bond,and a DNA biosensor (GCE/PTh/PB-Au/GN/ssDNA) was prepared.The preparation processes of DNA biosensors were characterized by electrochemical impedance spectroscopy (EIS),cyclic voltammetry (CV) and differential pulse voltammetry (DPV).The DNA was detected with the sensor by differential pulse voltammetry (DPV) using methylene blue (MB) as hybridization indicator.The results exhibited linear response (r=0.994) to DNA and slope of curve (-13.4 μA/decade) in the concentration range from 1.0×10^-14~1.0×10^-6 mg/L with a lower detection limit of 1.0×10-14 mg/L.The sensor prepared is sensitive and accurate which makes it applicable not only for gene detection but also for detection of heavy metal ion and organic pollutant.

Key words: DNA；polythionine, prussian blue nanoparticals, gold nanoparticals； electrochemistry, biosensor