A homogeneous magnetic bead-based impedance immunosensor for highly sensitive detection of Escherichia coli O157:H7

As foodborne pathogen contamination has become a threat to human health worldwide, early detection of pathogen is significant. Traditional electrochemical immunosensors for pathogen detection involve electrode modification or samples adsorption on the electrode which affect the detection sensitivity and electrode reproducibility, thereby limiting their further application in POCT (point of care testing). We established a homogeneous magnetic bead-based electrochemical impedance system using interdigitated gold electrodes as sensing elements for high sensitivity detection of Escherichia coli. (E. coli) O157:H7. The system avoided electrode modification and sample matrix adsorption, and greatly improved detection sensitivity. The detection limit of this method for E.coli O157:H7 was 10(2) colony-forming units per milliliter (CFU mL(-1)), coefficient of variation (CV) < 10 % (n = 3), which was three orders of magnitude lower than the traditional ELISA method, and the linearity detection range was 10(2) CFU mL(-1) to 10(6) CFU mL(-1). This magnetic bead-based impedance method is expected to be used for a wider range of pathogen targets analysis.