Fabrication of MIL-101(Fe)/MWCNTs-COOH hybrid material for ultra-sensitive electrochemical monitoring of ciprofloxacin in actual matrices

The extensive use of ciprofloxacin (CIP) has raised growing concerns regarding environmental pollution, food safety, and public health, thereby driving an urgent demand for rapid, sensitive and cost-effective detection methods. Herein, an electrochemical sensing platform is constructed by integrating MIL-101(Fe) with MWCNTs-COOH, which synergistically couples the effective analyte preconcentration and catalytic Fe–O active sites of MIL-101(Fe) with the exceptional conductivity and large surface area of MWCNTs-COOH. Notably, the reversible Fe 2+ /Fe 3+ redox cycle in MIL-101(Fe) facilitates rapid electron shuttling, further amplifying the electrochemical signal toward CIP oxidation. This dual-functional interface enables simultaneous preconcentration and signal amplification, yielding a broad linear response spanning 0.05–15 μM, accompanied by a high sensitivity of 5.6492 μA·μM −1 , as well as an ultralow LOD of 0.006 μM. Additionally, this sensor also demonstrates outstanding selectivity, good repeatability, excellent reproducibility, and durable stability, retaining approximately 96.1% of its initial current signal after 21 days of storage. Furthermore, to rigorously validate practical feasibility, acceptable recoveries between 92.9% and 105.3% were measured in honey, tap water, and CIP eye drops, demonstrating its versatility across food, environmental, and pharmaceutical matrices. Overall, this work establishes a design blueprint for high-performance electrochemical sensors based on MIL-series MOF/carbon composites, opening new avenues for rapid, on-site antibiotic monitoring to ensure food safety, environmental protection, and pharmaceutical quality control.