Application of enhanced Raman techniques in life sciences and biomedicine

Current understanding of complex biological processes and structures relies entirely on available imaging and sensing techniques. As many of these investigation tools suffer from severe limitations, the need for methods which can provide new insight is growing rapidly. Enhanced Raman techniques are becoming increasingly important research tools in biosciences thanks to their unique non-destructive, non-invasive and label-free nature. This work aimed to demonstrate the capabilities of enhanced Raman techniques in life sciences and biomedicine research. The techniques used in this work were surface-enhanced Raman spectroscopy (SERS) and coherent anti-Stokes Raman scattering (CARS). While SERS uses the enhancement of Raman signals by utilising nanoparticles CARS utilises non-linear optical effects to increase signals. Furthermore, SERS is utilised as an analytical technique using spectral information while CARS is used for chemically selective imaging at a vibrational frequency of molecular bond. The studies in this thesis explore the broad scope of applications of both these enhanced Raman techniques. SERS was used for detection of different bacterial strains, where it was shown that using nanopatterned surfaces resulted in improved distinction compared to use of nanoparticles. SERS was also applied to monitor of intracellular metabolic processes. The effect of different treatments to differentiate SHSY-5Y cells was studied and the changes observed were correlated with biochemical analysis. Additionally, novel SERS nanoparticle probes and their potential in life sciences was also investigated. CARS was used to study stem cell differentiation and food deprivation in nematodes. In both the cases the effect of chemical modulators and treatments was also studied. The results showed that label-free imaging using CARS is a viable and superior alternative to conventional staining used to study these processes in biological sciences. Overall, the work in this thesis establishes the use of SERS and CARS as potent tools in the life sciences