Preparation of a composite sensor based on a fluorescent and magnetic molecular imprint polymer for metronidazole extraction–detection

[Display omitted] •Fluorescent and magnetic nanoprobe was developed for the extraction-detection of MNZ.•MFMIP provided an easy way to isolate MNZ with a magnetic field.•SPR studies were conducted to evaluate the interaction MFMIP-MNZ.•The kinetic constants of association/dissociation between MFMIP-MNZ were obtained.•The MFMIP sensor detected MNZ in water samples at concentrations ranging 5–60 μM. We developed a metronidazole (MNZ)-selective sensor, combining magnetic and fluorescent molecularly imprinted polymers (MFMIP) with a non-imprinted reference composite (MFNIP). Using isothermal titration calorimetry (ITC), we optimized the MNZ-to-APTES ratio during polymerization, obtaining a specific MNZ-APTES bonded complex (Kb= 2.575 × 103 L/mol, ΔH° = −1.079 kJ mol−1, TΔS° = 18.389 kJ mol−1, and ΔG° = −19.468 kJ mol−1). The MFMIP composite, incorporating Fe3O4@TEOS magnetite nanoparticles and CdTe@TGA quantum dots, exhibited cavity-specific interactions with MNZ, as confirmed by surface plasmon resonance (SPR) studies. Compared to MFNIP, the MFMIP sensor demonstrated superior selectivity in water samples (5–60 μM, with LOD and LOQ values of 1.28 and 5.00 μM), and even in the presence of interferents. In addition, the use of CdTe quantum dots enabled real-time analysis via Stern–Volmer quenching mechanisms without complex sample preparation. In conclusion, our MFMIP sensor offers sensitive and selective MNZ detection. It presents practical advantages, including real-time analysis and ease of handling, making it a promising extraction–determination system for trace concentrations of MNZ.