Upconversion particle@Fe3O4@molecularly imprinted polymer with controllable shell thickness as high-performance fluorescent probe for sensing quinolones.

Localized photo-polymerization was ingeniously applied to prepare a multifunctional molecularly imprinted polymer (MIP) fluorescent probe using the "layer-by-layer" assembly of MIP and Fe3O4 nanoparticles on NaYF4: Yb3+, Er3+ upconversion particles (MUCPs@MIP). Enrofloxacin was used as the template and chosen as the target molecular during the investigation of the adsorption property. This ternary probe has magnetic and broad-spectrum molecular recognition capability, fast response, and upconversion fluorescence. The results of the fluorescence quenching analysis showed good linear ranges of 1.03nmol/L to 0.28μmol/L for enrofloxacin, 1.69nmol/L to 0.22μmol/L for fleroxacin, 6.92nmol/L to 0.28μmol/L for levofloxacin, 7.54nmol/L to 0.30μmol/L for ciprofloxacin, and 3.90nmol/L to 0.25μmol/L for enoxacin. This probe was further used to determine five quinolones in fish tissues and the recoveries ranging from 90.33% to 108.43% were obtained with relative standard deviation below 5.53%. This work offers a new and general strategy to synthesize a MUCPs@MIP upconversion fluorescence probe with magnetic and selective molecular recognition capability for rapid and accurate sensing of multiple chemical residues in the environment and agri-food products.