Fabrication of DNA functionalized carbon nanotubes/Cu2+ complex by one-step electrodeposition and its sensitive determination of nitrite

In this paper, DNA functionalized single-wall carbon nanotubes/Cu2+ (DNA–CNTs/Cu2+) complex was one-step electrodeposited onto the glassy carbon electrode (GCE), which fabricated a DNA–CNTs/Cu2+/GCE sensor to detect nitrite. Cyclic voltammogram of DNA–CNTs/Cu2+/GCE showed a pair of well-defined redox peaks for Cu2+/Cu+. Compared with DNA–CNTs/GCE and DNA–Cu2+/GCE, the prepared DNA–CNTs/Cu2+/GCE exhibited more excellent electrochemical properties. Thus, the prepared DNA–CNTs/Cu2+/GCE was proposed as nitrite sensor. The effects of Cu2+, CNTs and DNA concentration in the mixture together with electrodeposition time and determination conditions such as applied potential, pH value on the current response of DNA–CNTs/Cu2+/GCE toward nitrite were optimized to obtain the maximal sensitivity. In addition, electrochemical experiments revealed that the modified electrode showed high electrocatalytic activity to the reduction of nitrite ion (NO2−). The linear range for the detection of NO2− was 3 × 10−8 to 2.6 × 10−3 M, and the response was very fast (less than 3 s). A low detection limit of 3 × 10−8 M (S/N = 3) for NO2− was achieved.