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Title: Photoelectrochemistry of immobilised photosynthetic components: From chlorophyll to intact chloroplasts
Author: Martin, Sophie
ISNI:       0000 0001 3620 2366
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2007
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This thesis aims to explore the use of scanning electrochemical microscopy (SECM) to investigate a range of processes, in particular fundamental electron transfer processes, connected to photosynthesis. These studies focus on several model systems ranging from LB films of chI a to intact chloroplasts. Electrochemical and scanned probe microscopy (SPM) techniques will be invaluable for monitoring these electron transfer processes and the structure - activity relationships in the systems of interest. A study of the different methods of chlorophyll film formation on solid supports and characterisation of these films with regard to surface coverage and film thicknesses has been explored with a range of techniques. Dropcast, spincast and LB films are investigated using UV-visible spectroscopy and AFM in order to elucidate the most appropriate chlorophyll film formation techniques for use in the later studies of this thesis. SECM has combined with an inverted microscope setup to investigate electron transfer in thin films of chlorophyll, with the aim of correlating the photoelectrochemical activity of the chlorophyll layer with the spatial organisation of the film. Using LB techniques, monolayers and multilayer films of chi a have been prepared on solid inert supports. It is clarified that electron transfer occurs from photo-excited chlorophyll to reduce oxygen. This is observed using SEeM, to electrochemically follow the transient change in oxygen concentration close to chlorophyll films upon illumination. The data obtained have been simulated using a commercial software package and used to determine kinetic parameters for this electron transfer process. This work is extended by considering the effects of electron transport in chI a molecules when deposited onto conducting electrode surfaces, compared to inert glass surfaces. These studies present some contradictory results to those previously published in literature and these findings have been discussed. ' The photosynthetic activity and surface structure of chloroplast and 'thylakoid membranes using SPM techniques and CLSM has been investigated. Factors such as illumination conditions, O2 evolution and reactions with different redox mediators will be studied to probe key steps in the electron transport chain reaction. Finally, confocal microscopy has been combined with SECM to study lateral proton diffusion at different phospholipid monolayers under a range of surface pressures. Therefore, investigating key diffusional processes as a model for those processes occurring at biological membranes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available