Abstract
Rapid and sensitive methods have been developed to detect foodborne pathogens, a development that is important for food safety. The aim of this study is to explore Surface-enhanced Raman scattering (SERS) with silver nano substrates to detect and identify the following three foodborne pathogens: Escherichia coli O157: H7, Staphylococcus aureus and Salmonella. All the cells were resuspended with 10 mL silver colloidal nanoparticles, making a concentration of 107 CFU/mL, and were then exposed to 785 nm laser excitation. In this study, the results showed that all the bacteria can be sensitively and reproducibly detected directly by SERS. The distinctive differences can be observed in the SERS spectral data of the three food-borne pathogens, and the silver colloidal nanoparticles can be used as highly sensitive SERS-active substrates. In addition, the assay time required only a few minutes, which indicated that SERS coupled with the silver colloidal nanoparticles is a promising method for the detection and characterization of food-borne pathogens. At the same time, principle component analysis (PCA) and hierarchical cluster analysis (HCA) made the different bacterial strains clearly differentiated based on the barcode spectral data reduction. Therefore, the SERS methods hold great promise for the detection and identification of food-borne pathogens and even for applications in food safety.
Highlights
For food safety management and monitoring, foodborne pathogens have always been an issue of concern as they can cause severe illness in humans via contaminated water or food (Zhao et al, 2017a)
After placing the silver colloidal nanoparticles for 4 h, the solution was still a clear and transparent light yellow with no deposition phenomenon, which indicates that the silver colloid has good stability
To understand the formation of the AgNP-bacteria complex, the Escherichia coli O157: H7 coated with silver nanoparticles was performed by Transmission electron microscopy (TEM)
Summary
For food safety management and monitoring, foodborne pathogens have always been an issue of concern as they can cause severe illness in humans via contaminated water or food (Zhao et al, 2017a). When the target analyte approaches or adsorbs certain rough metal (gold, silver, etc.) nanoparticle surfaces, the signals can be enhanced by many orders of magnitude compared to normal RS (Sivanesan et al, 2014). This method handles samples and provides the basis for non-destructive and ultra-sensitive detection of samples (Wang and Irudayaraj, 2012). SERS inherits rich chemical fingerprint information from RS, which can be conveniently made under ambient and aqueous conditions It gains sensitivity by plasmonenhanced excitation and scattering and has a narrow width that is suitable for multiplex analysis (Zong et al, 2018). The study showed that the accuracy of the identification results of each different step was in the range of 90.6–99.5%
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