CoOOH-based colorimetric aptasensor with dual cascade amplification for ultrasensitive monitoring of fleroxacin in honey

The abuse or misuse of fleroxacin (FLE) in aquaculture and livestock may elevate FLE residues in foods, posing a serious threat to human health. Consequently, FLE detection has garnered extensive attention in food science. This study developed a magnetic separation-assisted colorimetric aptasensor for ultrasensitive FLE detection, leveraging the enhanced nanozyme activity of CoOOH nanoflakes with hairpins and dual cascade amplification (CHA-HCR). Under optimal experimental conditions, the proposed aptasensor exhibited high specificity for FLE with a wide linear range (1–100 nM) and a detection limit as low as 758 pM. Furthermore, the colorimetric aptasensor demonstrated robust performance in FLE-spiked honey analysis, achieving 96.70–101.06 % recoveries with 2.42–5.45 % RSDs, which showed strong agreement with commercial ELISA results. This study establishes a simple and effective platform for sensitive FLE detection in honey samples, demonstrating significant potential for practical food safety monitoring.