I. Noiseux, J.-P. Bouchard, P. Gallant, P. Bourqui, H. Cao, M. Vernon, R. Johnson, S. Chen, O. Mermut "Detection of foodborne pathogens by nanoparticle technology coupled to a low cost fluorescence cell reader" Proc. of SPIE, 7553, art. no. 75530C, 2010
Résumé: The detection, identification and quantification of pathogenic microorganisms at low cost are of great interest to the
agro-food industry. We have developed a simple, rapid, sensitive, and specific method for detection of food-borne
pathogens based on use of nanoparticles alongside a low cost fluorescence cell reader for the bioassay. The nanoparticles
are coupled with antibodies that allow specific recognition of the targeted Listeria in either a liquid or food matrix. The
bioconjugated nanoparticles (FNP) contain thousands of dye molecules enabling significant amplification of the
fluorescent signal emitted from each bacterium. The developed fluorescence Cell Reader is an LED-based reader
coupled with suitable optics and a camera that acquires high resolution images. The dedicated algorithm allowed the
counting of each individual nanoparticles-fluorescent bacterial cells thus enabling highly sensitive reading. The system
allows, within 1 hour, the recovery and counting of 104 to 108 cfu/mL of Listeria in pure culture. However, neither the
Cell Reader nor the algorithm can differentiate between the FNPs specifically-bound to the target and the residual
unbound FNPs limiting sensitivity of the system. Since FNPs are too small to be washed in the bioassay, a dual tagging
approach was implemented to allow online optical separation of the fluorescent background caused by free FNPs.
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