A NIR-responsive up-conversion nanoparticle probe of the NaYF4:Er,Yb type and coated with a molecularly imprinted polymer for fluorometric determination of enrofloxacin

The paper describes the preparation of a fluorescent probe based on the use of up-conversion particles (UCPs) of the type NaYF 4 : Er, Yb and shelled with a molecularly imprinted polymer (MIP) that is specific for the antibiotic enrofloxacin. The upconverted green luminescence emitted by the UCPs upon photoexcitation at 980 nm was used to locally generate a thin MIP shell around the UCPs via photopolymerization. Enrofloxacin is used as the template, and ethylene glycol dimethacrylate (EGDMA) as the cross-linking agent. It is found that enrofloxacin is well captured by the MIP and then quenches the fluorescence of the UCPs. Fluorescence decreases linearly in the 63 ng·L −1 to 60 μg·L −1 enrofloxacin concentration range, with a 8 ng·L −1 limit of detection. The method was applied to the determination of enrofloxacin in spiked fish samples. Recoveries ranged from 83.7 to 87.7%, with relative standard deviations between 2.0 and 5.5% (for n  = 3). Schematic of an NIR-responsive up-conversion nanoparticle probe of the NaYF 4 :Er,Yb type and coated with a MIP for fluorometric determination of enrofloxacin. The upconverted luminescence emitted by the UCPs was used to locally generate a thin MIP shell around the UCPs via photopolymerization.