Aptamer-based surface enhanced Raman spectroscopy (SERS) for the rapid detection of Salmonella Enteritidis contaminated in ground beef

A rapid and specific aptamer-based surface enhanced Raman spectroscopy (SERS) for the detection of S. enterica at a serovar level was developed. The aptamer was modified in this research with an additional short chain adenine and a fluorescein molecule. The aptamer-based SERS method could differentiate between S. enterica subsp. Enteritidis (S. Enteritidis) and S. enterica subsp. Gaminara (S. Gaminara) and allowed the in-vitro detection of S. Enteritidis at 3 log CFU/mL. The SERS characteristic peaks of the aptamer at 1184 and 730 cm-1 were used as reporters for the presence of S. Enteritidis as it binds specifically to that bacterium. Whereas, those peaks were not observed in the spectra of S. Gaminara, suggesting that the aptamer-based SERS was specific to S. Enteritidis but not S. Gaminara. The efficacy of the method to detect S. Enteritidis contaminated in ground beef (93% lean) was also determined. The observed increase of peak intensity at 726-732 cm-1 in the SERS spectra of S. Enteritidis (4 log CFU/g) inoculated samples apparently confirmed that the method can be a promising tool to specifically detect the presence of S. Enteritidis in ground beef with a total running time of 4 h.