Rapid screening detection of fluoroquinolone residues in milk based on turn-on fluorescence of terbium coordination polymer nanosheets

Abstract We report a facile, effective and rapid screening method for the determination of total fluoroquinolones (FQs) in milk using lanthanide coordination polymer nanomaterials as the sensing platform. The non-luminescent coordination polymer nanosheets (CPNSs) used in this work are composed of adenosine monophosphate (AMP) and terbium (Tb3+) ions (AMP/Tb CPNSs). The as-prepared CPNSs were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy and fluorescence techniques. Tb3+ acts as the center ion of the coordination polymer, with AMP assembled through phosphate and amine groups. However, the reaction between FQs and AMP/Tb CPNSs noticeably turns on the fluorescence due to the strong coordination interaction between FQs and Tb3+. Under optimized conditions, the fluorescence intensity of AMP/Tb at 545 nm shows a linear relationship with FQ concentrations between 0.04 μmol/L and 5.0 μmol/L. The relative standard deviation (RSD) of the intraday precision is below 1%, and detection limits are as low as 0.01 μmol/L. The proposed method was successfully applied to the determination of FQs in milk samples.