First label-free carbohydrate-based electrochemical sensor to detect Escherichia coli pathogenic bacteria using affinity between adhesion FimH and mannose on the glassy carbon electrode

First label-free carbohydrate-based electrochemical sensor to detect Escherichia coli pathogenic bacteria using affinity between adhesion FimH and mannose on the glassy carbon electrode

Controlling water and food contamination by pathogenic organisms requires quick, simple, and low-cost methods. Using affinity between mannose and type I fimbriae in the cell wall of Escherichia coli (E. coli) bacteria as evaluation elements compared to the conventional plate counting technique enables a reliable sensing platform for the detection of bacteria. In this study, a simple new sensor based on electrochemical impedance spectroscopy (EIS) for rapid and sensitive detection of E. coli was developed. Biorecogniton layer of the sensor was formed by covalent attachment of p-carboxyphenylamino mannose (PCAM) to gold nanoparticles (AuNPs) electrodeposited on the surface of glassy carbon electrode (GCE). The resultant structure of PCAM was characterized and confirmed using FTIR. The developed biosensor demonstrated a linear response with a logarithm of bacterial concentration (R2 = 0.998) in the range of 1.3 × 10 1~ 1.3 × 106 CFU.mL−1 with the limit of detection of 2 CFU.mL−1 within 60 min. The sensor did not generate any significant signals with two non-target strains, demonstrating high selectivity of the developed biorecognition chemistry. Selectivity of the sensor and its applicability to analysis of the real samples was investigated in samples of tap water and low-fat milk. Overall, the developed sensor has shown to be promising for the detection of E. coli pathogen in water and low-fat milk due to its high sensitivity, short detection time, low cost, high specificity, and user-friendliness.