Detection of salmonella using surfaced enhanced Raman scattering

Abstract

The use of Surface Enhanced Raman Scattering (SERS) for biological detection has brought up the question of detection limits and how these detection limits apply to the application. For most biological detection uses of SERS, a high detection probability is needed for a relatively small amount of biological specimen. This is especially true for the detection of S. enteriditis (Salmonella) bacteria that may be present on minute concentrations , for example, in food products. Using SERS we have identified the associated antibody conjugated with 12nm diameter Au colloid. Our preliminary results show small fractals with a disperse distance of about 1 monomer diameter (12nm) between the colloidal gold monomers may enhance the SERS emission. We also investigate the possibility that a conformation change may induce an increase in the aromatic amino acid contribution. We then compare the antibody SERS alone to SERS of antibody conjugated to Salmonella bacteria. The use of SERS as a bacterial detection method leads to the possibility for detection of small amounts (<10,000 bacteria/ml) of Salmonella bacteria. In our study we obtained a detection limit of 10⁶ bacteria/ml using gold as a SERS active substrate.