Fabrication of highly sensitive and selective electrochemical sensor by using optimized molecularly imprinted polymers on multi-walled carbon nanotubes for metronidazole measurement

A novel electrochemical sensor for determining metronidazole (MNZ) is developed based on a composite structure of molecularly imprinted polymer (MIP) and multi-walled carbon nanotubes (MWCNTs). The morphology characterization by SEM displayed the successful deposition of polymeric layer on MWCNTs surface. A series of parameters including loading quantity of MWCNTs, pH value of polymerization system, and ratio of template and monomer are investigated and optimized during sensor preparation. It is clearly found that the MIP-decorated MWCNTs significantly enhance the electric signal response in MNZ measurement, giving rise to a remarkably low detection limit of 4.92 × 10^-5 mg L^-1 (S/N = 3), while the electro-synthesized MIP layer affords simultaneous identification and quantification of the target molecules by using Fe(CN)₆^3-/4- as probe to indicate the current intensity. In addition, the established sensor is completely reusable and maintains excellent stability. These predominant properties enlist this hybrid electrode to exhibit high reliability for analyzing real samples and detection of MNZ directly in pharmaceutical dosage form and in fish tissue is successfully carried out without assistance of any separation techniques.