Flexible Microelectrode-Based Impedance Immunosensor for Rapid Detection of \u3ci\u3eE. coli\u3c/i\u3e O157:H7

Abstract

Abstract Food contamination poses a significant threat to public health, the economy, and human health worldwide, occurring at any stage of the food supply chain, from farm to fork. Escherichia coli 0157:H7, recognized as one of the principal causes of foodborne illness, poses a considerable risk to food safety. The primary objective of this investigation is to devise a flexible microelectrode-based immunosensor capable of swiftly identifying E. coli O157:H7 cells without the need for incubation in a pure culture environment. In the development of the biosensor, the gold electrode (composed of 50% Au) underwent an initial coating process involving 2-aminoethanethiol/cysteamine, followed by functionalization with glutaraldehyde to serve as a linker, and subsequent immobilization with anti-E. coli polyclonal antibodies (pAbs). The determination of the optimal concentration of cysteamine and glutaraldehyde for sensor development revealed an optimal concentration of 20 mg/mL. Upon interaction between anti-E. coli pAbs and E. coli O157:H7, a substantial increase in impedance amplitude from 2.7 to 6.93 kΩ was observed, highlighting the efficacy of the immunosensor in detecting the target pathogen when compared to a bare electrode. Furthermore, the developed immunosensor exhibited the capability to detect E. coli O157:H7 cells with a detection limit ranging from 101 to 103 CFU/mL without the requirement of an incubation period. Visual confirmation of successful binding of E. coli O157:H7 onto the flexible microelectrode-based immunosensor was achieved through scanning electron microscopy imaging, providing insights into the adherence of bacterial cells to the microelectrode surface. Keywords: Foodborne pathogens, flexible biosensors, electrochemical immunosensor; rapid detection; Escherichia coli O157:H