9 - Applications in Medicine

Abstract

This chapter focuses on the applications of micro-Raman spectroscopy in medicine. Raman scattering is a vibrational spectroscopic technique that can both fingerprint components of biological and biomedical species and identify polymorphs of crude mixtures, extracts, cells and chromosomes. The difficulties which arise in the application of Raman microprobe spectroscopy in biomedicine are basically the same as those encountered in conventional Raman spectroscopy. They include the small Raman cross-section which results in very low signal levels, the possibility of sample damage and the strong fluorescence background which is often observed in the spectra of crude biomedical extracts and mixtures, tissues and cells. Surface-enhanced Raman scattering (SERS) spectroscopy offers the possibility of circumventing many of the problems of conventional Raman spectroscopy, as well as in its microscopic applications. Molecules adsorbed on metal surfaces are found to have an unusually large Raman cross-section under certain conditions. In this phenomenon the optical properties of molecules in the vicinity of the solid surface are modified. The magnitude of the Raman scattering cross-section is usually enhanced, to an extent which depends on the chemical nature of the adsorbed molecules, the type of metal surface and its structure. The greatest enhancement occurs for molecules adsorbed on silver, gold, or copper. This technique has been found to be very useful in increasing the spectral sensitivity, thus yielding new information on both organic and inorganic molecules. Raman microscopy not only complements the other biochemical methods, but also offers the attractive features of superior mass sensitivity, molecular specificity and in situ applicability.