Detection of Biological Species by Surface Enhanced Raman Scattering

In recent years there has been a strong interest in the development of rapid detection techniques of biological species, especially pathogens that are involved in food poisoning, water contamination, and air-borne diseases. Conventional detection methods are time consuming and usually involve overnight culture of bacteria in a suitable growth medium. In this study we used surface-enhanced Raman scattering (SERS) to develop a rapid method of identifying bacteria. Molecules in close contact to the nanometallic surfaces show a huge enhancement in their Raman signature. The enhancement can be as great as 1010. We also explored the application of dry nanostructured surfaces to characterize biomolecules by softly landing them on plasma-etched silver surfaces. By such landings, biomolecular gas phase ions were allowed to chemically bind to the surface so that the Raman effect was significantly enhanced and fluorescence was suppressed.