One Stone Two Birds: An Upconversion Nanosensor for Sensitive Detection of Fluoroquinolones in Aquatic Products Based on Chelation Recognition

Excessive residues of fluoroquinolones (FQs) in aquatic products have become a growing issue in recent years. Herein, we demonstrate an upconversion fluorescence nanosensor constructed by a one-stone-two-birds strategy, where Fe3+ not only quenches upconversion fluorescence with high efficiency but also specifically recognizes the bidentate ligand structure of FQs. Compared to existing methods, the proposed sensor is simpler to synthesize and cheap and has more storage stability due to the unification of the quencher and recognition molecule. Enrofloxacin (ENR) was chosen as a representative veterinary drug for FQs to verify the effectiveness of the nanosensor. Under optimal conditions, the range of detection for ENR was 2.0 × 10–2 to 2.0 × 102 μg/mL, with a limit of detection of 1.08 × 10–3 μg/mL. The developed nanosensor was further validated by high-performance liquid chromatography–ultraviolet (HPLC-UV) without significant differences in practical detection. Hence, this study offers a potential strategy for the detection of FQs.