Construction of Norfloxacin Electrochemical Sensors Based on Density Functional Theory and Surface Molecularly Imprinting Technology

Using density functional theory (DFT) for calculation, four kinds of functional monomers that might interact with norfloxacin (NOR) were screened, and methacrylic acid (MAA) was selected as the optimal functional monomer. By using chitosan/multiwalled carbon nanotubes (CS-MWCNTs) as matrix, NOR as template, MAA as functional monomer, surface molecularly imprinting polymer (SMIP)-NOR@CS/MWCNTs were prepared by “grafting polymerization synchronized with crosslinking/imprinting” method. The structure and morphology of polymer were characterized by scanning electron microscope, infrared spectroscopy and X-ray photoelectron spectrometer. The adsorption performance and mechanism of SMIP-NOR@CS/MWCNTs for NOR were explored. The SMIP-NOR@CS/MWCNTs modified glassy carbon electrode (SMIP-NOR@CS/MWCNTs/GCE) was constructed by drop-coating method. The electrochemical performance of the sensor was studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The results showed that SMIP-NOR@CS/MWCNTs had excellent binding affinity for NOR, and imprinting factor was 2.71. The variation of DPV current response showed a good linear relationship with NOR concentration in the range of 0.1–1.5 nmol/L and 1.5–140 nmol/L, respectively, and with a detection limit of 0.026 nmol/L. The sensor exhibited excellent selectivity, stability, reusability and reproducibility. The method presented good practical application performance in detecting NOR in water and milk samples with recoveries of 97.5%–103.3%, and the results had no significant differences compared with those of high-performance liquid chromatography method.