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Journal of Nanomaterials
Volume 2013 (2013), Article ID 706354, 8 pages
Research Article

Facile and Sensitive Epifluorescent Silica Nanoparticles for the Rapid Screening of EHEC

1Department of Microbiology, Food Safety Center, Faculty of Science, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand
2Department of Microbiology, Kasetsart University, Bangkok 10900, Thailand

Received 3 January 2013; Accepted 21 April 2013

Academic Editor: Mohamed Bououdina

Copyright © 2013 Pravate Tuitemwong et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study was to develop antibodies conjugated fluorescent dye-doped silica nanoparticles (FDS-NPs) aiming to increase signals for the rapid detection of Escherichia coli O157:H7 with glass slide method. The FDS-NPs were produced with microemulsion/sol-gel techniques resulting in spherical in shape with 47 ± 6 nm in diameter. The particles showed high intensity and stable orange color Rubpy luminescent dye. The XRD spectrum showed a broad diffraction peak in the range of (centered at ) indicating an amorphous structure. Surface modifications for bioconjugation with affinity chromatography purified (IgGs) antibodies were successful. The properties were evident from FTIR spectra at 1631.7  . Results indicated that nanoparticles could attach onto cells of E. coli O157:H7 coated on a glass slide, and give distinctively bright color under epifluorescence microscope (400x). It was shown that FDS-NPs could detect a very low amount of cells of E. coli O157:H7 (16 CFU in 10 ml) in 60 min. The phosphate buffered saline (PBS) with ionic strength of 1.70 gave zeta potential of good particle dispersion (−40 mV). This work demonstrated that highly sensitive bioconjugated E. coli O157:H7 FDS-NPs were successfully developed with a potential to be used for the rapid detection of E. coli O157:H7 in foods.