An electrochemical aptamer sensor for rapid quantification sulfadoxine based on synergistic signal amplification of indole and MWCNTs and its electrooxidation mechanism

Unreasonable disposal of sulfadoxine (SDX) causing food safety and eventually result water pollution, and shows great significance of detection. A sensitive unit Aptamer (Apt) was adopted to construct an electrochemical sensor BSA/Apt/indole/MWCNTs/GCE with the synergistic amplification of multi -walled carbon nanotubes (MWCNTs) and indole for the detection of SDX. Optimization of the conditions allowed the detection of SDX shows a wide linear range from 0.10 to 1000.00 mu mol/L by differential pulse voltammetry (DPV). The LOD and sensitivity were determined to be 0.033 mu mol/L and 0.29 mu A/(mu mol/L & sdot;cm2), respectively. The recovery rate of SDX in pork and lake water samples range 98.57 %-104.93 %, 93.6 %-106.2 %, respectively. Both the relative standard deviation (RSD) was lower than 7.40 %, which proved that the sensor has good practicability. In addition, DFT calculation was established that a restricted of B3LYP and a basis set of 6-31 G, the electrooxidation of SDX involves two -electron and one -proton transfer.