Fiber optic biosensor employing Alexa-Fluor conjugated antibodies for detection of <i>Escherichia coli</i> O157:H7 and Shiga-like toxins

Shu-I Tu; Tao Geng; Joe Uknalis; Arun Bhunia

doi:10.1117/12.686316

23 October 2006 Fiber-optic biosensor employing Alexa-Fluor conjugated antibodies for detection of Escherichia coli O157:H7 and Shiga-like toxins

Shu-I Tu, Tao Geng, Joe Uknalis, Arun Bhunia

Author Affiliations +

Proceedings Volume 6381, Optics for Natural Resources, Agriculture, and Foods; 638106 (2006) https://doi.org/10.1117/12.686316
Event: Optics East 2006, 2006, Boston, Massachusetts, United States

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.

Citation Download Citation

Shu-I Tu, Tao Geng, Joe Uknalis, and Arun Bhunia "Fiber-optic biosensor employing Alexa-Fluor conjugated antibodies for detection of Escherichia coli O157:H7 and Shiga-like toxins", Proc. SPIE 6381, Optics for Natural Resources, Agriculture, and Foods, 638106 (23 October 2006); https://doi.org/10.1117/12.686316

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