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Open AccessArticle

A Label-Free Impedance Immunosensor Using Screen-Printed Interdigitated Electrodes and Magnetic Nanobeads for the Detection of E. coli O157:H7

1
Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701, USA
2
Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR 72701, USA
3
College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China
4
Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA
5
College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310068, China
*
Author to whom correspondence should be addressed.
Academic Editors: Nicole Jaffrezic-Renault and Carole Chaix
Biosensors 2015, 5(4), 791-803; https://doi.org/10.3390/bios5040791
Received: 15 October 2015 / Revised: 5 December 2015 / Accepted: 11 December 2015 / Published: 15 December 2015
(This article belongs to the Special Issue Affinity Sensors)
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 104.45 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 104 cfu·mL−1 and 107 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. View Full-Text
Keywords: immunosensor; magnetic nanobeads; impedance; screen-printed interdigitated electrode; E. coli O157:H7; rapid detection immunosensor; magnetic nanobeads; impedance; screen-printed interdigitated electrode; E. coli O157:H7; rapid detection
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MDPI and ACS Style

Wang, R.; Lum, J.; Callaway, Z.; Lin, J.; Bottje, W.; Li, Y. A Label-Free Impedance Immunosensor Using Screen-Printed Interdigitated Electrodes and Magnetic Nanobeads for the Detection of E. coli O157:H7. Biosensors 2015, 5, 791-803.

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