title: A Label-Free Impedance Immunosensor Using Screen-Printed Interdigitated Electrodes and Magnetic Nanobeads for the Detection of E. coli O157:H7.
abstract: Escherichia coli O157:H7 is one of the leading bacterial pathogens causing foodborne illness. In this study, an impedance immunosensor based on the use of magnetic nanobeads and screen-printed interdigitated electrodes was developed for the rapid detection of E. coli O157:H7. Magnetic nanobeads coated with anti-E. coli antibody were mixed with an E. coli sample and used to isolate and concentrate the bacterial cells. The sample was suspended in redox probe solution and placed onto a screen-printed interdigitated electrode. A magnetic field was applied to concentrate the cells on the surface of the electrode and the impedance was measured. The impedance immunosensor could detect E. coli O157:H7 at a concentration of 10(4.45) cfu·mL(-1) (~1400 bacterial cells in the applied volume of 25 μL) in less than 1 h without pre-enrichment. A linear relationship between bacteria concentration and impedance value was obtained between 10(4.45) cfu·mL(-1) and 10(7) cfu·mL(-1). Though impedance measurement was carried out in the presence of a redox probe, analysis of the equivalent circuit model showed that the impedance change was primarily due to two elements: Double layer capacitance and resistance due to electrode surface roughness. The magnetic field and impedance were simulated using COMSOL Multiphysics software.
authors.affiliation: Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701, USA. rwang@uark.edu.
authors.forename: Ronghui
authors.initials: R
authors.lastname: Wang
authors.affiliation: Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR 72701, USA. jlum@pacificvetgroup.com.
authors.forename: Jacob
authors.initials: J
authors.lastname: Lum
authors.affiliation: Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701, USA. zcallawa@uark.edu.
authors.forename: Zach
authors.initials: Z
authors.lastname: Callaway
authors.affiliation: College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China. jianhan@cau.edu.cn.
authors.forename: Jianhan
authors.initials: J
authors.lastname: Lin
authors.affiliation: Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA. wbottje@uark.edu.
authors.forename: Walter
authors.initials: W
authors.lastname: Bottje
authors.affiliation: Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701, USA. yanbinli@uark.edu.|Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR 72701, USA. yanbinli@uark.edu.|Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA. yanbinli@uark.edu.|College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310068, China. yanbinli@uark.edu.
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Li
mesh_terms: D000818:Animals; D055910:Antibodies, Immobilized / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D002417:Cattle; D017097:Electric Impedance; D004566:Electrodes; D004867:Equipment Design; D004927:Escherichia coli Infections / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods; D057230:Limit of Detection; D008280:Magnetics / Q000295:instrumentation / Q000379:methods; D059346:Magnets / Q000737:chemistry; D000069466:Red Meat / Q000382:microbiology*
chemical_list: D055910:Antibodies, Immobilized
keywords: E. coli O157:H7; immunosensor; impedance; magnetic nanobeads; rapid detection; screen-printed interdigitated electrode