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Title: Surface-enhanced Raman scattering spectroscopy for rapid bacterial screening

item Chao, Kuanglin - Kevin Chao
item Kim, Moon
item Yang, Chun Chieh
item QIN, JIANWEI - University Of Maryland
item Liu, Yongliang

Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 6/20/2010
Publication Date: 6/21/2010
Citation: Chao, K., Liu, Y., Kim, M.S., Yang, C., Qin, J. 2010. Surface-enhanced Raman scattering spectroscopy for rapid bacterial screening. ASABE Annual International Meeting.

Interpretive Summary: Due to public health risks and economic losses that can result from outbreaks of foodborne illnesses, the development of rapid and accurate methods to identify pathogenic bacteria is needed for food safety screening applications. Surface-enhanced Raman scattering (SERS) spectroscopy was investigated for the development of a rapid spectroscopy-based screening method to identify bacteria. Characteristic SERS bands were identified at 712 and 390 wavenumbers for prepared bacteria-colloid mixtures of E. coli, Listeria, and Salmonella. These SERS bands were incorporated into two-waveband ratios, I390 / I352 and I712 / I730, which could be used to differentiate between the three bacteria cultures with 100% success. On the basis of practical implementation, this study suggests that simple procedures can be used to produce silver colloids and assess their quality, to prepare bacterial cultures for SERS analysis, and to analyze the SERS spectra for the differentiation of E. coli, Listeria, and Salmonella. These procedures for SERS-based analysis avoid the need to perform the processes of labeling, purifying, separating, drying, or washing the bacterial samples that are typically necessary for other laboratory screening methods, and also are advantageous in requiring only about 20 minutes for bacteria-colloid mixture preparation and SERS measurement with the use of relatively small samples. This SERS technique for screening for the presence of these bacteria can be useful to regulatory government agencies and the food processing industries as a rapid.

Technical Abstract: This study reports the feasibility of citrate-reduced colloidal silver SERS for differentiating three important foodborne pathogens, E. coli, Listeria, and Salmonella. FT-Rama and SERS spectra of both silver colloids and silver colloids mixed with tripotassium phosphate were collected and analyzed to evaluate the reproducibility and stability of silver colloids fabricated in a batch-production process. The results suggest that the reproducibility of the colloids over the batch process is high and that their binding effectiveness remains consistent over a 60-day storage period. Two specific SERS bands were identified at the 712 and 390 wavenumbers, and these were used to develop two-band ratios for differentiating E. coli-, Listeria-, and Salmonella-colloid mixtures with a 100% success. These results indicate that colloidal silver SERS technique can be a practical alternative method suitable for rapid screening of E. coli, Listeria, and Salmonella bacteria.