Conducting polymer functionalized Cu-metal organic framework-based electrochemical immunosensor for rapid and sensitive quantitation of Escherichia coli O157:H7.

Escherichia coli (E. coli) O157:H7 is an important food-borne pathogen that can cause hemorrhagic diarrhea and enteritis in humans and animals. Realizing the rapid quantitation of E. coli O157:H7 is of great significance for the guarantee of food safety and disease control. In this study, an electrochemical immunosensing technique based on a functionalized composite of Cu-metal organic framework (Cu-MOF) and poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT:PSS) is developed, achieving rapid and sensitive quantitation of E. coli O157:H7 in food and clinical feces samples. The organic functionalization of Cu-MOF significantly improves the interface conductivity to facilitate electron transfer and provides the sulfonic groups (-SOH) to conjugate bio-recognizing elements for target determination. The immunosensor delivers a linear detection range of 3 × 10 ~ 3 × 10 cfu/mL, a low limit of detection (LOD) of 7.4 cfu/mL, and a short analysis time of 40 min. In addition, it does not show any cross-reactivity with other common pathogens and exhibits high repeatability with relative standard deviations (RSDs) all lower than 2.09%, providing a promising approach for warranting  food safety and control of E. coli O157:H7 disease.