Rapid detection of Salmonella in milk by a label-free electrochemical immunosensor based on CoFe-MOFs@MWCNTs modified electrode

Abstract

Electrochemical sensors exhibit distinct advantages over alternative sensor modalities in the swift detection of microorganisms. In this study, we devised a label-free electrochemical immunosensor utilizing CoFe-MOFs@MWCNTs composite-modified electrodes for the specific detection of Salmonella in milk. The integration of CoFe-MOFs@MWCNTs composites onto the electrode surface effectively enhanced the current response and furnished an abundance of active sites, subsequently augmented by electrodeposited AuNPs for signal amplification and antibody conjugation. The microstructural characteristics of the CoFe-MOFs@MWCNTs composite were meticulously examined via scanning electron microscopy, while its elemental composition and chemical structure were thoroughly analyzed using energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy, respectively. Upon optimization of the experimental parameters, the sensor demonstrated exceptional sensitivity, specificity, and stability, exhibiting a linear detection range spanning from 1.04 × 10⁴ to 1.04 × 10⁸ CFU mL⁻¹ for Salmonella, with a limit of detection (LOD) of 2.89 × 10³ CFU mL⁻¹. In this study, we combined the sensitivity of electrochemical methods and the specificity of immunological reactions with experimental signal amplification from a variety of nanomaterials to achieve sensitive detection of Salmonella. This innovative sensor holds promise for the detection of Salmonella in cow's milk and presents a novel approach for monitoring foodborne pathogens.