Electrochemical responses of the DE-DNA biosensor were also investigated in the research (Fig. 1). Fig. 1(A) shows the cyclic voltammogram of different modified dual-probe electrodes was tested in TMB substrate by dual-channel electrochemical analyzer. There were two pairs of redox peaks at the surface of HRP/capture probes (HRP/C1 and HRP/C2) modified electrodes exposed in TMB substrate, and the prominent catalytic Tempol peaks were both found in CV of HRP/C1 and HRP/C2 electrodes (Fig. 1(A), curve (a)). From Fig. 1(B), the intensity of current signals were shown more directly from channel 1 (curve (a), 16900 nA) and channel 2 (curve (a), 17,100 nA). This reflected that HRP had been fastened onto the different capture probes modified electrodes via streptavidin–biotin affinity binding. Along with the catalysis of HRP, TMB was oxidized into a colored compound by H2O2, and thousands of reduction reactions of H2O2 could be efficiently catalyzed, leading to significantly amplified electrochemical current signals (Volpe et al., 1998).