Electrochemical sensor based on magnetic molecularly imprinted polymers and Cu2+ for the detection of amoxicillin residuals in milk

Abstract. Amoxicillin has been widely used in dairy cattle production. However, this may cause a threat to human health, especially when amoxicillin residues remain in milk. Therefore, highly sensitive monitoring of the amoxicillin residues in milk is essential. This paper prepared a cost-effective, simple, and highly sensitive magnetic molecularly imprinted polymers (MMIPs) electrochemical sensor for indirect amoxicillin detection. The MMIPs were synthesized by sol-gel process using Fe3O4@SiO2 as a core, amoxicillin as a template, trimethoxyphenylsilane as a functional monomer, tetraethoxysilane as a cross-linking agent, then removal of the template molecules. The MMIPs were characterized by scanning electron microscope, transmission electron microscopy, vibrating sample magnetometer, and Fourier transform infrared spectra. The MMIPs electrochemical sensor was prepared by a complex of Cu2+ and the MMIPs of rebinding the template, which modified on the surface of magnetic glassy carbon electrode. Here, Cu2+ was used as the signal tracer and amplifier of the MMIPs electrochemical sensor. Then the response peak currents of Cu re-oxidized to Cu2+ were recorded by differential pulse voltammetry and used to monitor the level of amoxicillin. Under the optimal conditions, the linear range of the developed MMIPs electrochemical sensor ranged from 1000 nM to 2 nM, with a detection limit of 1.87 nM (3σ). Furthermore, the MMIPs electrochemical sensor showed high selectivity to determine amoxicillin, and it was also successfully applied to detect amoxicillin in milk.