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Journal of Nanomaterials
Volume 2014, Article ID 851905, 6 pages
Research Article

Rubpy Dye-Doped Silica Nanoparticles as Signal Reporter in a Dot Fluorescence Immunoassay Strip

1Program in Bioscience, Faculty of Science, King Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand
2Department of Medical Sciences, National Institute of Health, Tiwanon Road, Nonthaburi 11000, Thailand
3Department of Physics, Faculty of Science, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand
4Department of Microbiology, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
5Food Safety Center, Institute of Scientific and Technological Research and Services, King Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand

Received 27 November 2013; Revised 3 January 2014; Accepted 4 January 2014; Published 18 February 2014

Academic Editor: William W. Yu

Copyright © 2014 Nualrahong Thepwiwatjit 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 paper describes an application of Rubpy dye-doped silica nanoparticles (RSNPs) as signal reporter in a dot fluorescence immunoassay strip for rapid screening of Vibrio cholera O1 (VCO1). These nanoparticles have a spherical shape with an average diameter of 45 nm. They appear luminescent orange when excited with a 312 nm UV lamp. Based on the sandwich immunoassay principle, a test strip was made of a nitrocellulose membrane dotted with monoclonal antibodies against VCO1 as analyte capture molecules. After introducing a test sample, followed by polyclonal rabbit anti-VCO1 antibody conjugated RSNPs as detection reporters and one washing step, the presence or absence of the target bacteria could be identified under UV light by naked eyes. A positive sample would signal a bright orange dot on the strip. The proposed assay had a detection limit of  cfu/mL and was successfully applied as a rapid screening test for VCO1 in food samples with high sensitivity, specificity, and accuracy.