2007 NSTI Nanotechnology Conference and Trade Show - Nanotech 2007 - 10th Annual

Development of SERS Spectroscopy for Routine and Rapid Identification of Escherichia Coli and Listeria Monocytogenes on Ag Colloidal Nanoparticles

Y-R Chen, Y. Liu, X. Nou and K. Chao
USDA/ARS Beltsville Agricultural Research Center, US

Keywords:
SERS spectroscopy, foodborne bacteria, food safety, nanoparticles, identification, rapid methods

Abstract:
Rapid, accurate, and preferably routine methods for the identification of foodborne bacteria are increasingly important, because of bio- /agro-terrorism threats, public health concerns, and economic loss. Conventional detection of bacteria is time-consuming, requiring 5-7 days, and is not sufficiently rapid to assure the safety of ready-to-eat food products. Although antibody- / nucleic acid-based systems and amplification-based methods have been developed as viable tools to detect bacteria, they often yield high rates of false negative/false positive identification and are slow in speed (>50 min). We conduct research to develop silver SERS substrate and nanoprobe based Raman systems for the rapid, consistent, and routine detection of foodborne toxins and pathogens in agricultural and food products. This paper presents the results of our examination of the reproducibility of Ag nanoparticle colloids over batches and the stability and binding effectiveness of Ag nanoparticle colloids over storage. We also characterize SERS bands with near-infrared (NIR) excitation for E. coli and L. monocytogenes, and found that two simple ratio algorithms could be used for rapid identification of E. coli and L. monocytogenes suspensions with 100% success. The result indicates that NIR SERS spectroscopy can potentially be used for routine detection and screening of bacteria.

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