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Interdigitated array microelectrode based impedance biosensor coupled with magnetic nanoparticle-antibody conjugates for detection of Escherichia coli O157 : H7 in food samples

Varshney, Madhukar and Li, Yanbin (2007) Interdigitated array microelectrode based impedance biosensor coupled with magnetic nanoparticle-antibody conjugates for detection of Escherichia coli O157 : H7 in food samples. BIOSENSORS & BIOELECTRONICS, 22 (11). pp. 2408-2414.

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Official URL: http://dx.doi.org/10.1016/j.bios.2006.08.030

Abstract

An impedance biosensor based on interdigitated array microelectrode (IDAM) coupled with magnetic nanoparticle-antibody conjugates (MNAC) was developed and evaluated for rapid and specific detection of E. coli O157:H7 in ground beef samples. MNAC were prepared by immobilizing biotin-labeled polyclonal goat anti-E. coli antibodies onto streptavidin-coated magnetic nanoparticles, which were used to separate and concentrate E. coli O157:H7 from ground beef samples. Magnitude of impedance and phase angle were measured in a frequency range of 10 Hz to 1 MHz in the presence of 0.1 M mannitol solution. The lowest detection limits of this biosensor for detection of E. coli 0 157:H7 in pure culture and ground beef samples were 7.4 x 10(4) and 8.0 x 10(5) CFU ml(-1), respectively. The regression equation for the normalized impedance change (NIC) versus E. coli O157:H7 concentration (N) in ground beef samples was NIC = 15.55N-71.04 with R-2=0.95. Sensitivity of the impedance biosensor was improved by 35% by concentrating bacterial cells attached to MNAC in the active layer of IDAM above the surface of electrodes with the help of a magnetic field. Based on equivalent circuit analysis, it was observed that bulk resistance and double layer capacitance were responsible for the impedance change caused by the presence of E. coli O157:H7 on the surface of IDAM. Surface immobilization techniques, redox probes, or sample incubation were not used in this impedance biosensor. The total detection time from sampling to measurement was 35 min. (c) 2006 Elsevier B.V. All rights reserved.

Item Type:Article
Uncontrolled Keywords:interdigitated array microelectrode; impedance biosensor; magnetic nanoparticles; bacterial detection; E. coli O157 : H7
Subjects:Analytical Science > Nanotechnology for sensing and actuating
Physical Science > Nano objects
Biomedical Science > Nanobiotechnology
Biomedical Science > Nanotechnology for human health
ID Code:2646
Deposited By:Anuj Seth
Deposited On:09 Jan 2009 12:25
Last Modified:20 Jan 2009 11:18

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