Fabricating a Novel Raman Spectroscopy-Based Aptasensor for Rapidly Sensing Salmonella typhimurium

A novel surface-enhanced Raman scattering (SERS) response emerging from aptamers, complementary DNA (cDNA), p-aminothiophenol (PATP), and Au nanorods (GNRs) for detection of foodborne pathogens sensitivity is proposed here. In the presence of Salmonella typhimurium (ST) and cDNA simultaneously, ST and cDNA would competitively combine with the S. typhimurium aptamer (STA), inducing a highly conformation changes of STA. Accordingly, STA no longer stabilizes the GNRs in salt solution, leading to the varying aggregation extent of GNRs. The varying GNR aggregation will give rise to the plasmonic coupling and display a strong SERS signal, which can be distinctly reflected by the attached PATP via a transition of signals typical from ST peaks to PATP peaks. Under optimal conditions, the SERS intensity was observed to increase linearly with ST concentration from 56 to 56 x 10(7) cfu/mL (R-2 = 0.971), with a LOD of 9 cfu/mL. Additionally, this aptasensor exhibits a high selectivity to other similar pathogens, and the ability of the bioassay to detect ST was also confirmed in adulterated milk samples.