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Biosensors 2015, 5(4), 791-803; doi:10.3390/bios5040791

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
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)
View Full-Text   |   Download PDF [528 KB, uploaded 15 December 2015]   |  

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 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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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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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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