Construction of a molecularly imprinted polymer electrochemical sensor based on g-C 3 N 4 /Cu-MOF for the detection of norfloxacin

The detection of norfloxacin (NOR) is crucial because the overdoes and accumulation may result in residues in environment in animal-derived foods, which can destroy ecology and cause disease for people. A molecularly imprinted electrochemical sensor based on g-C 3 N 4 /Cu-MOF was constructed for the selective detection of norfloxacin in this paper. The g-C 3 N 4 /Cu-MOF was synthesized by melamine pyrolysis and solvothermal method followed by ultrasonic mixing. After drop casting g-C 3 N 4 /Cu-MOF on glassy carbon electrode, the molecularly imprinted film was synthesized by electropolymerization. The composite was analyzed by powder X-ray diffractometer, field emission scanning and transmission electron microscope, and Fourier transform infrared spectroscopy. The electrochemical properties of the sensor were characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and pulse voltammetry. The results show that the composite of g-C 3 N 4 /Cu-MOF efficiently decreased the charge transfer resistance of electrode and improved the electron transfer kinetic between analyte and electrode with the improved current response and increased active area. After optimizing conditions of the ratio of functional monomers to template molecules, the number of polymerization cycles, accumulation time, electrolyte pH, and the sensor exhibits excellent response toward NOR with the linearity range of 0.02–0.1 μmol/L and 1–120 μmol/L and the limit of detection of 6.67 nmol/L. Moreover, it shows good selectivity, anti-interference, and reproducibility properties. In the real sample detection of pharmaceutical formulations, serum and milk, the sensor shows an acceptable recovery rate and standard deviation.