|Tu, Shu I|
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 10/12/2006
Publication Date: 10/24/2006
Citation: Tu, S., Geng, T., Uknalis, J., Bhunia, A.K. 2006. Fiberoptic biosensor employing alexa-fluor conjugated antibody for detection of escherichia coli o157:h7 and shiga-like toxins. Proceedings of SPIE. 6:(6381:638106-1). Interpretive Summary: The Centers for Disease Control have estimated that E. coli O157:H7 bacteria cause 73,000 cases of serious illness and 61 deaths in the United States each year. The illness has been associated with the Shiga-like toxins (SLTs) secreted by the bacteria. Thus, there is a need to develop sensitive, specific and rapid detection of the bacteria and their SLTs. We have developed a new biosensor assay based on a commercially-available, portable fiber optic waveguide. This assay can detect both E. coli O157:H7 and SLTs from the same food samples within 36 hours. The whole detection biosensor and battery pack can be carried in a briefcase, allowing assays to be performed at the farm, processing plant, distribution center, and retail store. This capability provides the food industry and regulatory agencies a new tool to combat foodborne disease and bio-terror threats.
Technical 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 against the bacteria or the toxins, was first immobilized on polystyrene fiber waveguides through a biotin-streptavidin reaction that served as the bacteria or 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'micro g/mL of pure SLTs and the SLTs associated with 100K E. coli O157:H7 cells at stationary phase after olfoxacin induction.