Chapter 10 - Surface-Enhanced Raman Scattering Spectroscopy: Electromagnetic Mechanism and Biomedical Applications

Abstract

This chapter deals with studies of the electromagnetic (EM) mechanism and biomedical applications of surface-enhanced Raman scattering (SERS), which are some of the most important and interesting applications. Raman scattering is extensively used as a powerful tool for the determination of molecular structures and nature of bonding in molecules because it allows selective structural, surface processes, interface reaction, and kinetic investigations of various kinds of molecules from gaseous molecules, liquid molecules, polymers, and biomolecules. SERS spectroscopy is a promising tool in analytical science because of the enormous enhancement factors that have increased the detection limits of a wide variety of molecules to the single-molecule level. Many earlier experiments concluded that SERS enhancement is determined more by EM field enhancement than by chemical enhancement. The EM and chemical enhancement factors, specificity of vibrational spectra, and insensitivity to the aqueous environment increase the applicability of SERS to the study of complex biological systems. Also, the development of diverse SERS probes made this technique a practical analytical tool for biomedical applications. This chapter consists of two sections. The first section discusses details of a microspectroscopic system that allowed mechanistic investigations of SERS by simultaneous measurements of plasmon resonance Rayleigh scattering spectra and SERS spectra from single silver (Ag) nanoaggregates and a direct demonstration of relationships between plasmon resonance and SERS. The second section explains biomedical applications of SERS with reference to cellular probing, biological imaging, and pathogen detection.