Ultra-sensitive detection of ciprofloxacin hydrochloride in milk by molecularly imprinted electrochemical sensor based on S-CoFe-MOFs/AuNPs

Ciprofloxacin hydrochloride is widely used to treat animal diseases. However, its chronic abuse has caused severe accumulation in animal-derived foods, which has seriously damaged human health. Thus, in this study, a novel molecularly imprinted electrochemical sensor (MIES) was designed for selective and ultra-sensitive detection of ciprofloxacin hydrochloride (CPFX) in milk. The sensor was based on the molecularly imprinted polymers (MIPs) synthesized with poly-pyrrole (PPy) as the functional monomer, AuNPs and S-CoFe-MOFs (CoFe-Metal organic frameworks coated with chitosan) as the Supporting materials, and CPFX as the template molecule. The electrochemical behavior of MIPs/S-CoFe-MOFs/AuNPs/GCE was studied by several electrochemical methods, which showed a wider detection linear range (0.05 ∼ 500 ng·mL-1) and lower detection limit (0.0033 ng·mL-1) than those in previous reports. The optimization of experiments confirmed the good selectivity and stability of the sensors----- with the milk sample recovery of 89.04∼110.26%, and the relative standard deviations (RSD) of less than 5.5%, which was close to HPLC. In conclusion, the sensor we constructed has a high selectivity and stability potential in detecting CPFX in milk.