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

Biosensors

Ronghui Wang¹  Jacob Lum⁵  Zach Callaway¹  Jianhan Lin³  Walter Bottje²  Yanbin Li¹  Nicole Jaffrezic-Renault⁴ 

[1]Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701, USA

[2] E-Mails:

[3]Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA

[4] E-Mail:

[5]College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China

[6] E-Mail:Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701, USA

[7]

[8]Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR 72701, USA

[9] E-Mail:

关键词: immunosensor;    magnetic nanobeads;    impedance;    screen-printed interdigitated electrode;    E. coli O157:H7;    rapid detection;   

DOI  :  10.3390/bios5040791

来源: mdpi

【 摘 要 】

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 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.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.