Pathogens in food and environment can be easily exposed to human during harvest, processing, and food handling and thus a huge issue to public health. Rapid bacterial detection methods are critical for quick identification of target pathogens, and of great research interest over the decades. Well-established rapid methods such as PCR and ELISA offers great sensitivity at the cost of complicated sample preparation and require pre-enrichment in most cases. In addition, PCR-based methods cannot differentiate live and dead bacteria which leads to false positive results. Surface-enhanced Raman spectroscopy (SERS) is a combination of Raman spectroscopy and nanotechnology, which can provide signature spectral information of the target analyte upon interaction with metallic nanostructures and has been widely applied to the characterization and detection of microorganisms. We have developed filter-based SERS mapping assays for detection of total and specific bacteria, which requires simple sample preparation procedures and can achieve low detection limit with adjustable sample volume. 4-mercaptophenylboronic acid (4-mpba) serves as a chemical label for total bacteria, which specifically bind to the diol structure on the bacterial cell wall. We also applied an aptamer specifically designed for <i>Salmonella enteritidis</i> to develop a filter-based rapid screening assay for target pathogen using ultra-fast Raman imaging. This method can rapidly identify and estimate the level of target pathogen in pure water and produce rinsed water within 3 hours. We also applied propidium iodide to SERS for live and dead validation. The success of combining the filtration technique with SERS mapping demonstrates the compatibility of the filter-based system with multiple SERS labels to serve various detection purposes and provides useful implications for future applications of the filtration technique in SERS-based bacterial screening methods.

Development of a filter-based SERS platform for total and specific bacterial detection

2019 Fall National Meeting

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