Nano-Biophotonics

Photonic techniques are the methods of choice for probing biological systems, as they are non-invasive, non-ionising, inexpensive, and are ubiquitous. When applied to the treatment and prevention of disease and for pathology in general, biophotonics offers a means to bridge the gap between understanding of molecular structures and their role in physiological functions. There is a wide range of such techniques used in imaging, assaying, bio-sensing, optical diagnosis, each of which has limitations as well as benefits. The experiments outlined in this thesis use nanotechnology to overcome the limitations of resolution, contrast and chemical specificity with photonic techniques in biology. The experimental work outlined in this thesis is divided over three chapters, the first of which is concerned with nanostructured metallic surfaces for use in surface enhanced Raman scattering (SERS) for protein assay applications. This chapter gives details of the methods used to produce and characterise SERS substrates using gold and silver thermally evaporated onto butterfly wing sections, together with the protocols developed for manufacturing biomimetic analogues of these naturally occurring nanostructures. The conjugation system designed to modify the metal surfaces for use in an avidin/biotin model protein binding assay is described, together with an account of the efficacy of the final assay. The results obtained show that such naturally occurring nanostructures, and their biomimetic analogues, are suitable for use as SERS substrates for wet protein binding assays. This work represents a major advance in the field of SERS assay. The experimental chapters describe experiments that use coherent Raman scattering (CRS) methods to probe the interactions between nanoparticles and live cell cultures, as well as provide chemically selective images of tissue samples.