Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.757413
Title: Towards micro-imaging with dissolution dynamic nuclear polarisation
Author: Gaunt, Adam P.
ISNI:       0000 0004 7430 2300
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2018
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Abstract:
Nuclear magnetic resonance (NMR) of small samples and nuclei with a low gyromagnetic ratio is intrinsically insensitive due to the received signal dependence on Boltzmann's statistics. This insensitivity can be partially overcome through the application of hyper polarisation techniques such as Dissolution Dynamic Nuclear Polarisation (D-DNP). It is hoped that the hyper polarised 13C signal received from labelled small molecules could facilitate imaging of metabolic and transporter processes in biological systems. In order to realise this, appropriate molecules and experimental hardware must be used. A detailed description of the experimental set-up used for carrying out DDNP is given and the system is characterised. the advantageous use of a dual iso-centre magnet system is elucidated with optimisation of acquisition of fast relaxing molecules. such a system allows for interrogation of processes with short relaxation times, not possible with traditional, stand-alone polarisers. To acquire the maximum amount of hyper-polarised 13C signal in an imaging experiment, parallel acquisition techniques have been implemented and the hardware designed with such goals in mind. Multiple coils have been used to allow accelerated image acquisition. As such this work has validated the SENSE algorithm for artefact free, image reconstruction on the micro-scale. These techniques require an array of coils which add to the complexity of the design of the probehead. Decoupling methods and array coil construction must be considered the methods used to ensure well isolated coils, such as geometric decoupling, are presented. The novel fabrication and implementation of micro-coils for imaging and spectroscopy of nL scale samples is presented this will help facilitate the acquisition of images showing metabolic processes in active transport in cells. By placing the coils close to the sample it is possible to gain sensitivity relative to the mass of the sample in question. To achieve signal detection on the order of nL a novel, exible micro-coil array has been fabricated and the results of NMR experiments carried out on both protons and 13C are shown. This is the final stage before integrating the coils with the D-DNP system. The acquisition of 13C signal with the micro-coils displays optimal electronic characteristics when compared with other detectors presented in the literature. The final goal of the work is to produce a system that is capable of micro imaging in small biological samples such as the Xenopus Oocyte with a view to monitoring metabolic processes and transportation without the need for the use of the large fluorescing proteins (GFP's) that have been used in previous work (1). The need for GFP's attached to metabolites results in the measured data being non-physical as the fluorescing protein is often much larger than the molecule being transported. It is hoped that the use of hyperpolarised small molecules (such as pyruvic acid) may be able to remove this need for GFP's in the study of metabolite transportation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.757413  DOI: Not available
Keywords: QC770 Nuclear and particle physics. Atomic energy. Radioactivity
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