Selective Detection of Trace Metronidazole by Using a Magnetic Molecularly Imprinted Polymer‐based Fluorescent Probe.

A magnetic molecularly imprinted polymer‐based fluorescent (MIP‐FL) probe has been synthesized by embedding glutathione‐stabilized gold nanoclusters (GSH‐AuNCs) and Fe3O4 nanoparticles (Fe3O4NPs) into silica composites. The Fe3O4NPs/AuNCs@MIPs are characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and UV–Vis absorption spectroscopy. The results show that the spherical Fe3O4NPs/AuNCs@MIPs contain a core‐shell structure with GSH‐AuNCs anchored on the surface of silica‐protected Fe3O4NPs. As a fluorescence probe (excitation: 360 nm, emission: 615 nm), Fe3O4NPs/AuNCs@MIPs can selectively detect metronidazole (MNZ) among other nitroimidazoles (ronidazole, ornidazole, and tinidazole). During the detection, the fluorescence intensity of the MIP‐FL probe drops gradually with increasing MNZ concentration. The sensitive linear range of the fluorescence probe is from 0 to 5 μM, and the limit of detection is 4.2 nM. After the recognition sites interact with the template, the occurrence of charge transfer from the GSH‐AuNCs to MNZ results in fluorescence quenching. Finally, a real sample test has been performed in spiked milk. Satisfactory recoveries spanning from 96% to 102% indicate that Fe3O4NPs/AuNCs@MIPs enable highly sensitive detection of MNZ based on fluorescence signal output, while the MIPs also have enrichment potential for the target from complex samples due to the magnetic properties. [ABSTRACT FROM AUTHOR]