Metal-organic framework with dual-loading of nickel/nitrogen-doped carbon dots and magnetic nanoparticles for fluorescence detection of fenitrothion in food samples

The development of precise methods for the residue assay of organophosphate toxin, fenitrothion, is of great significance in minimizing its side effects on human life and the environment. Herein, a magnetic fluorimetric nanosensor for fenitrothion was constructed via embedding the nickel and nitrogen-doped carbon dots and Fe3O4 nanoparticles into the zeolitic imidazolate framework-8 (ZIF-8). The prepared nanosensor combines the advantages of Fe3O4 nanoparticles (magnetic separation and enriching the target analyte) and ZIF-8 (excellent adsorption capability) with high sensitivity of Ni,N-carbon dots. Magnetic ZIF-8 nanocrystals were used as ideal adsorbents to catch and accumulate fenitrothion, and Ni,N-carbon dots were exploited as optical materials to produce stable and strong fluorescence signals. We observed that the fluorescence signal of the ZIF-based nanocomposite (with excitation/emission maxima at 340/450 nm) was dynamically quenched by fenitrothion via the electron transfer process. Hence, a platform was designed for the assay of fenitrothion with a detection limit of 0.8 nM. The practicability of this method was verified by the quantification of fenitrothion in real food samples.