Construction of molecularly imprinted voltammetric sensor based on Cu N C polyhedron porous carbon from Cu doping ZIF-8 for the selective determination of norfloxacin

In this paper, a protocol of the integration of Cu doped porous carbon (CuCN) and molecularly imprinted polymer (MIP) was proposed to develop a sensitive, selective, and stable electrochemical sensor toward the determination of norfloxacin (NFX). Field-emission scanning electron microscopy and transmission electron microscope, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller analysis and thermogravimetric analyzer, cyclic voltammetry, and electrochemical impedance spectroscopy were used to characterize the doping materials and the MIP film. CuNC porous carbon was prepared by high-temperature carbonizing Cu/ZIF-8 precursor. The doping of Cu into ZIF-8 allows not only enhancing the conductivity for the sensor by giving active sites, but also favors the great porous structure and active surface area by prohibiting the structure collapse of ZIF-8 polyhedron. The MIP layer was prepared by in-situ electrochemical polymerization of dual monomers of dopamine and resorcinol on glassy carbon electrode (GCE) modified by CuNC. For the electrochemical detecting, the condition of the ratio of two functional monomers, functional monomer to template molecular, the number of electric polymerization cycles, pH, and incubation time were optimized. The proposed MIP/CuNC/GCE sensor allows the sensitive detecting toward NFX with the linear ranges of 0.01–0.5 and 0.5–100 μM and the limit of detection of 3.33 nM (S/N = 3). In addition, the sensor has good selectivity, repeatability, reproducibility, and stability. In terms of practical application, the sensor is feasible and robust in determination of NFX in the commercially available tablet with the average recovery of 96.72 %–103.88 % and RSD less than 5 %.