2011 Annual Report 1a.Objectives (from AD-416) To develop a nanobiosensor to detect Salmonella using surface-enhanced Raman scattering (SERS) technique:. 1)determine SERS characteristics of Salmonella;. 2)develop chemometric models to differentiate Salmonella from other bacteria;. 3)classify different Salmonella strains; and. 4)evaluate detection limits of nanobiosensor. 1b.Approach (from AD-416) We will develop methodologies to test and validate the SERS techniques. A series of experiments will be conducted based on the following methods:. 1)Design, fabricate SERS substrate to optimize for lower detection limits;. 2)Salmonella sample preparation;. 3)SERS measurement;. 4)Test and validate classification models for different serotypes;. 4)Test detectability from different background flora. 3.Progress Report This project is related to Objective 3 of in-house project: Develop and evaluate detection methods for foodborne pathogens and toxins with nanotechnology. Research has focused on surface modification with silver metals and determination of surface enhanced Raman spectroscopy (SERS) characteristics on thin titanium coated glass slides as metal nanosubstrates to improve sensitivity and detectability for Salmonella typhimurium in the forms of live and dead cells. For surface enhanced Raman spectroscopy (SERS) measurements, the bacteria cells were exposed to laser diode at 785 nm excitation, then Raman shifts were acquired from 200 to 2400 cm-1. Spectral signatures were compared to differentiate between live and deal cells. These spectral signatures indicated the structural changes in bacterial cell components.