Geraghty, Conor (2024) The Design, Synthesis, and Evaluation of Nitroreductase Triggered Sensors and Theranostics. PhD thesis, National University of Ireland Maynooth.

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Abstract

Poorly developed vasculature results in low intracellular O2 regions within tumour tissues. Such areas of hypoxia are under intense reductive stress due to the lack of O2 and lead to the upregulation of oxidoreductase enzymes such as nitroreductases (NTRs). NTRs are a particularly valuable marker for reductive stress being capable of reducing nitroaromatics to corresponding amino derivatives, a feature that has been exploited in the design of hypoxia sensitive fluorescent imaging agents. To date, 1,8-naphthalimide fluorophores have attracted considerable attention owing to their exceptional fluorescence characteristics, making them ideal candidates for the design of NTR responsive fluorescent probes. Given their synthetic versatility, which allows for the consequential modulation of fluorescence, coupled with their inherent sensitivity and selectivity, 1,8-naphthalimide fluorophores are considered highly applicable for monitoring NTR activity in hypoxic environments. This thesis entitled ‘The Design, Synthesis, and Evaluation of Nitroreductase Triggered Sensors and Theranostics’ is divided into 6 chapters and begins with Chapter 1, an introductory chapter which provides a literature review regarding the background and current research in the field of cancer, hypoxia, fluorescent sensors, and NTR based 1,8-naphthalimide fluorescent sensors. This chapter also outlines the aims and the objectives of the research carried out within this thesis. Chapter 2 details the synthesis and luminescence response of 3 novel Ru(II) polypyridyl complexes, a moiety not yet exploited for NTR sensing. It was proposed that the MLCT emission of these compounds could be quenched by nitroaromatic moieties allowing for an OFF-ON luminescence response in the presence of NTR. These complexes exhibited luminescence Turn-ON responses towards NTR, with one compound in particular displaying a significant OFF-ON response coupled with sensitivity and selectivity towards NTR. This compound was further investigated with regards to its DNA binding ability as well as its potential as an imaging agent for NTR in cellulo. Chapter 3 introduces four novel self immolative dendrimers designed to elicit a blue to green ratiometric fluorescent response in the presence of NTR. The synthesis of these dendrimers through the use of carbamate bond formation allows for the modulation of either fluorophore or prodrug. The fluorescent response of each probe was evaluated first by using a reducing agent and then by NTR under physiological conditions. One compound in particular established remarkable change in fluorescence as well as exceptional selectivity towards NTR, showcasing the utility of such a design as a self immolative theranostic approach for NTR sensing. Chapter 4 presents two novel fluorescence sensors for NTR described as quaternarised phenanthroline-naphthalimide conjugates. By quaternarization of the phenanthroline moiety, a compound with water solubility and potential DNA binding ability is achieved through its cationic nature, without the requirement of a heavy metal. Both compounds were observed to be responsive towards NTR with one of the compounds displaying both exceptional sensitivity towards varying concentrations of NTR and selectivity towards NTR in comparison to other biologically relevant species. Chapter 5 consists of a thesis summary that outlines the key findings and future work for each chapter. Subsequently, Chapter 6 includes the general experimental procedures as well as the synthesis and characterisation of all compounds. Literature references are also provided, followed by the Appendix which consists of the spectroscopic data that validates the work described in the main text.

Item Type:	Thesis (PhD)
Keywords:	Design; Synthesis; Evaluation; Nitroreductase Triggered Sensors; Theranostics;
Academic Unit:	Faculty of Science and Engineering > Chemistry
Item ID:	18880
Depositing User:	IR eTheses
Date Deposited:	13 Sep 2024 13:49
URI:
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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