Electrochemical aptasensor for the detection of tetracycline with multi-walled carbon nanotubes amplification

Herein, we present a simple electrochemical tetracycline (TET) aptasensor with multi-walled carbon nanotubes (MWCNTs) modification. MWCNTs were dropped on the glassy carbon electrode (GCE) to immobilize the anti-TET aptamer and to construct the aptasensor. The stepwise assembly process of the aptasensor was characterized by cyclic voltammetry. Results demonstrated that the peak currents of Fe(CN)63−/Fe(CN)64− redox pair decreased due to the formation of anti-TET/TET complexes on the modified electrode. The optimization of the loading amount of MWCNTs, the incubating conditions of aptamer and the detection time of TET were investigated in details. Under optimal conditions, the peak currents change obtained by DPV increased linearly with the increasing TET concentrations in the range from 1 × 10−8 M to 5 × 10−5 M with a linear coefficiency of 0.995. This electrochemical aptasensor has a detection limit of 5 × 10−9 M and was successfully applied to the determination of TET in spiked milk samples.