In this study an impedance aptasensor was designed for sensitive, selective, and fast detection of tetracycline (TET) based on an interdigital array microelectrode (IDAM). The IDAM was integrated with impedance detection to miniaturize the conventional electrodes, enhance the sensitivity, shorten the detection time, and minimize interfering effects of non-target analytes in the solution. Due to their excellent conductivity, good biocompatibility, the multi-walled carbon nanotubes (MWCNTs) were used to modify the IDAM to immobilize TET aptamer effectively. The proposed aptasensor produced a sensitive impedance change which was characterized by the electrochemical impedance spectroscopy (EIS). With the addition of TET, the formation of TET-aptamer complex on the surface of MWCNTs modified electrode resulted in an increase of electron transfer resistance (R et). The change of R et depends on the concentration of TET, which is applied for the quantification of TET. A wide linear range was obtained from 10-9 to 10-3 M. The linear regression equation was y(ΔR) = 21.310 × x(LogC) (M) + 217.25. It was successfully applied to detect TET in real milk samples.
Keywords: Aptasensor; Impedance; Interdigital array microelectrode; Multi-walled carbon nanotubes; Tetracycline.