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Proceedings Paper

Fiber optic biosensor employing Alexa-Fluor conjugated antibodies for detection of Escherichia coli O157:H7 and Shiga-like toxins
Author(s): Shu-I Tu; Tao Geng; Joe Uknalis; Arun Bhunia
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Paper Abstract

We developed an antibody-based fiber-optic biosensor to rapidly detect low levels of Escherichia coli O157:H7 and shiga-like toxins (SLTs) in ground beef samples. The principle of the sensor is a sandwich immunoassay using an antibody which is specific for E. coli O157:H7 or toxins. A polyclonal antibody was first immobilized on polystyrene fiber waveguides through a biotin-streptavidin reaction that served as the bacteria and toxin capture entity. Alexa Fluor 647 dye-labeled antibodies against E. coli O157:H7 or SLTS incubated with the waveguides were used to detect cells or toxin and generate a specific fluorescent signal, which was acquired by launching a 635 nm laser-light from an Analyte-2000. Fluorescent molecules within several hundred nanometers of the fiber were excited by an evanescent wave, and a portion of the emission light from fluorescent dye transmitted by the fiber and collected by a photodetector at wavelengths of 670 to 710 nm quantitatively. This immunosensor was specific for E. coli O157:H7 compared with multiple other foodborne bacteria. The approach was also able to detect ~0.5 μg/mL of pure SLTs and the the SLTs associated with 10 5 E. coli O157:H7 cells at stationary phase after olfoxacin induction.

Paper Details

Date Published: 23 October 2006
PDF: 6 pages
Proc. SPIE 6381, Optics for Natural Resources, Agriculture, and Foods, 638106 (23 October 2006); doi: 10.1117/12.686316
Show Author Affiliations
Shu-I Tu, USDA Agricultural Research Service (United States)
Tao Geng, Purdue Univ. (United States)
Joe Uknalis, USDA Agricultural Research Service (United States)
Arun Bhunia, Purdue Univ. (United States)

Published in SPIE Proceedings Vol. 6381:
Optics for Natural Resources, Agriculture, and Foods
Yud-Ren Chen; George E. Meyer; Shu-I Tu, Editor(s)

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