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标题：A Label-Free Impedance Immunosensor Using Screen-Printed Interdigitated Electrodes and Magnetic Nanobeads for the Detection of E. coli O157:H7
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作者：Ronghui Wang ; Jacob Lum ; Zach Callaway 等
期刊名称：Biosensors
电子版ISSN：2079-6374
出版年度：2015
卷号：5
期号：4
页码：791-803
DOI：10.3390/bios5040791
出版社：MDPI Publishing
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 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.
关键词：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