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

•Electrode modification and samples adsorption restrict the application of electrochemical biosensing.•Magnetic bead-based impedance biosensor avoids matrix interference and improves electrode reproducibility.•Interdigital electrode and enzymatic reaction system enhance detection efficiency.•Escherichia coli O157:H7 could be analyzed with highly sensitivity.