Ultrasensitive and rapid detection of Escherichia coli O157:H7 in beef juice using immunoassay based on field-effect enzymatic detection

Ultrasensitive and rapid detection of E. coli O157:H7 in beef juice was carried out using a novel immuno-detection approach. The detection system was realized by incorporating the recently developed technique of field-effect enzymatic detection with the immunosensing method. The detection of unprocessed samples resulted in a detection limit of 19 CFU mL-1 with an assay time of 67 min. The ultrasensitive detection of the original sample was due to the intrinsic amplification provided by the system. The direct detection without performing pre-enrichment significantly shortened the assay time. The voltage-controlled signal amplification of the detection system also facilitated the transduction of the electrical signal through the bulky immune complex so that the detection did not rely on the use of mediators or other diffusional substances. The novel detection approach can be used as a detection platform for ultrasensitive, specific and rapid detection of microorganisms and other types of analytes that can be detected using immunoassay. © 2014 The Royal Society of Chemistry.