Ultrasensitive detection of E. coli O157:H7 with biofunctional magnetic bead concentration via nanoporous membrane based electrochemical immunosensor

Ka Yiu Chan, Wei Wei Ye, Yu Zhang, Li Dan Xiao, Hang Mei Polly Leung, Yi Li, Mo Yang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

85 Citations (Scopus)


In this paper, biofunctional magnetic beads were investigated for bacterial cells concentration in a nanoporous alumina membrane based immunosensor for ultra-sensitive detection of E. coli O157:H7. The specific antibody modified magnetic beads were used for concentration of E coli O157:H7 from samples in a small region to enhance sensitivity. The magnetic bead conjugated E. coli O157:H7 cells were then captured on the nanoporous alumina membrane with immobilized antibody via assembled PEG-silane linker. Scanning electron microscopy and fluorescent microscopy were used to demonstrate the magnetic bead-bacteria cell conjugation and bacteria cells magnetic concentration, respectively. Impedance spectroscopy was used to monitor the pure E coli O157:H7 cells and magnetic bead conjugated E coli O157:H7 cells binding on antibody immobilized nanoporous membrane with or without magnetic field. Compared with direct detection of pure bacteria cells, this method via magnetic bead conjugation and concentration demonstrated the ultrasensitivity of 10. CFU/mL for E coli O157:H7 detection.
Original languageEnglish
Pages (from-to)532-537
Number of pages6
JournalBiosensors and Bioelectronics
Issue number1
Publication statusPublished - 15 Mar 2013


  • Bacteria detection
  • Impedance sensor
  • Magnetic bead concentration
  • Nanoporous membrane

ASJC Scopus subject areas

  • Biotechnology
  • Biophysics
  • Biomedical Engineering
  • Electrochemistry

Cite this