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A Chemiluminescence Fiber-Optic Biosensor Coupled with Immunomagnetic Separation for Rapid Detection of E. Coli O157:H7
- Ye, J., Liu, Y., Li, Y.
- Transactions of the ASAE 2002 v.45 no.2 pp. 473-478
- Campylobacter jejuni, Escherichia coli O157, Listeria monocytogenes, Salmonella Typhimurium, antibodies, bacteria, biosensors, chemiluminescence, detection limit, fiber optics, immunomagnetic separation, magnetic fields, peroxidase, rapid methods, regression analysis
- A biosensor, consisting of a chemiluminescence reaction cell, a fiber-optic light guide, and a luminometer linked to a PC, was developed in conjunction with immunomagnetic separation for rapid detection of E. coli O157:H7. The sample containing E. coli O157:H7 was first incubated with anti- E. coli O157:H7 coated magnetic beads and horseradish peroxidase (HRP) labeled anti- E. coli O157:H7 antibodies to form antibody-coated bead - bacteria - HRP-labeled antibody sandwich complexes. Then, a magnetic field was applied to separate the sandwich complexes from the sample, and the HRP in the complexes catalyzed the reaction of luminol and H 2 O 2 in the reaction cell. The cell number of E. coli O157:H7 was determined by collecting the HRP-catalyzed chemiluminescence signal from the bead surface though a fiber-optic light guide and measuring the signal with a luminometer. Key parameters for the biosensor, such as magnetic bead volume, HRP-labeled antibody concentration, incubation time, and blocking agent, were determined for optimum operation conditions. The chemiluminescence biosensor was selective to E. coli O157:H7 in the presence of other bacteria in the sample, including Salmonella typhimurium , Campylobacter jejuni , and Listeria monocytogenes . The detection limit of the biosensor was 1.8 × 10(2) CFU/mL, and the chemiluminescence signal ranged from 3.8 to 241.0 mV, corresponding to E. coli O157:H7 cells from 1.8 × 10(2) to 4.5 × 10(5) CFU/mL. A regression model with R 2 = 0.958 was established for a calibration curve over the detection range. The biosensing procedure was simple and rapid, and could be completed within 1.5 h.