APPLICATIONS OF RAMAN SPECTROSCOPY

This thesis is devoted to exploring experimental applications of Raman spectroscopy. The ability of Raman spectroscopy to investigate the vibrational modes of a molecule was explored in several studies. The work included using Raman spectroscopy to examine the molecular configuration of proteins, the relative amounts of certain molecules present in a nanoporous material, the enhanced scattering properties of nano-structures and finding the local temperature of nanowire materials. The primary research project presented in this thesis focused on determining the structural conformation of lysozyme in a variety of contact lens solutions and the relation to its functionality. Protein activity was established by the use of micrococcal assays. The two multipurpose solutions tested, BioTrue and ReNu, as well as a neutralized hydrogen peroxide solution, ClearCare, showed no indications of major structural alterations in the lysozyme when exposed to the separate solutions. The assay experimental data indicated a consistently high protein activity during exposure to the various solutions. Both the data indicating a native structural conformation and high degree functionality result in the conclusion that the multipurpose solutions do not denature lysozyme during a regular cleaning cycle. The non-neutralized ClearCare and the other hydrogen peroxide solution, UltraCare (both neutralized and non-neutralized), demonstrated signs of lysozyme denaturation within a time period of a typical cleaning cycle, due to structural changes to the protein. However, the functionality of non-neutralized UltraCare and ClearCare (by the micrococcal assay) were both found to remain relatively high, seemingly contradicting the structural indications of denaturation. This discrepancy between the structure and function of the proteins may be attributed to the irreversible process of aggregation that occurs at the high concentrations of protein which are require to produce a strong Raman signal. However, the relatively lower concentration of lysozyme used in the assay experiments better reflect the true amounts found in the tear film. Thus, the conclusion can be made that if lysozyme is denatured by the majority of the solutions, they are only reversibly denatured, posing minimal risks when reintroduced back into the eye. The only contact lens solution that may pose the potential for inducing an inflammatory response to permanently denatured lysozyme is following exposure to neutralized UltraCare. The exact reason for this permanent denaturation seems to be from the components of the neutralizing tablet, but this requires further investigation. Raman spectroscopy was also employed in several additional research projects for other graduate groups. The first side project involved the use of heptane to wash away only