A novel sensor based upon surface-enhanced Raman scattering (SERS) has been constructed by immobilizing colloidal silver particles onto the distal end of an optical fiber. This same single fiber was then used to both transport the exciting laser radiation and collect the Raman scattering from analytes sorbed onto the colloidal particles. The colloidal particles were immobilized by functionalization of the end of the optical fiber with (3-aminopropyl)trimethoxysilane prior to immersion of the fiber in silver colloid. Spectra were obtained from both 4-(5′-azobenzotriazol)3,5-dimethoxyphenylamine and crystal violet. The within-batch variation of a set of five fibers has been measured as approximately 10%. Raman imaging experiments demonstrated that the effects due to spatial variations in the intensity of the SERS recorded over the distal end of the fiber are removed by the use of a multimode fiber.

A combined surface enhanced resonance Raman scattering (SERRS) and transmission electron microscopy (TEM) method has been developed allowing the same immobilised nanoparticles to be reliably located and studied by both techniques. The method allows large numbers of particles to be analysed by each technique relatively simply and the distribution of Raman enhancement between particles and clusters, as well as the relationship between particle microstructure and Raman enhancement, to be investigated. In addition, the effect of chemical and laser damage on the dye on the surface of the particles and the effect on the particles can be systematically investigated. These effects can cause time dependence fluctuations in Raman signals which could be confused with "blinking" from single molecules. Conditions were identified to enable Raman scattering to be detected without photodegradation to either the analyte molecules or the particles. Measurement outside this range gave rise to alterations in the spectra and to loss of signal. The extent of the damage to the analyte/particle if these conditions are not adhered to gives rise for concern about interpretation of changes in spectra observed unless an attempt is made to assess the limits of the conditions which can be applied before photodegradation or sample drying occurs. The method developed will enable reliable and systematic studies of the enhancement obtained from immobilised single particles by enabling the full power of high resolution TEM to be utilised to aid the development of a reliable SERRS theory.

Surface-enhanced resonance Raman scattering (SERRS) is a very sensitive and selective detection method that can be used for the analysis of both DNA and P-450s. A number of factors have limited the broader application of the technique. These limitations are described and addressed. An approach to reduce the problems associated with variation of the silver colloids used to provide surface enhancement and chemical methodologies that ensure surface adsorption are presented. A practical approach was used to investigate the nature of the effect. This approach has highlighted the importance of resonance enhancement for ultimate sensitivity. Two approaches to achieve successful detection of DNA using SERRS are described, and, using these two approaches, the possibility of multiplexing is also demonstrated. The analysis of proteins by SERRS is discussed and P-450 is presented as a specific example of the information that may be gained from SERRS of proteins.