The main purpose of this work is to calculate the isotropic shielding of some nuclei, other than protons, of first- and second-row atoms in the periodic table and some transition metal elements in a wide variety of molecular environments, with a view to gaining an understanding of the various electronic factors which determine the observed nuclear shielding. Chapter One introduces some general concepts. Chapter Two presents a general servey of various Semi-empirical molecular orbital methods. Various MO calculations of nuclear shielding are briefly reviewed in Chapter Three with particular emphasis on Pople's GIAO-MO approach. This chapter also contains a description of the theory of medium effects on nuclear shieldings. Chapter Four is concerned with approximate MO theories and their application to the GIAO-MO method for Sum-Over-State (SOS) results of some shieldings of first-row elements. The medium effect models are used to explore the role of medium effects on nuclear shielding. This exploration is supplemented by performing some calculations on hydrogen-bonded models. Chapter Five records the SOS results for the nuclear shielding of some second-row elements in conjunction with the GIAO-MO method. The solvaton model is also used in an attempt to improve on our understanding of the relation between magnetic shielding and various features of molecular electronic structure. Chapter Six presents some shielding data for transition metal elements obtained by means of Pople's GIAO-MO method in conjunction with the INDO/5R parameterization scheme for SOS results of some inorganic molecules. A reasonable correlation between the calculated and experimental chemical shifts, compared by mean of a least-squares fit is obtained for some of the molecules considered.

Beta-induced fluorescence (BIF) is the luminescence excited from a compound as a result of the passage of beta-particle radiation through a compound or dilute solution of a compound. A liquid chromatographic detector, based on the principle of BIF, has been developed which allowed the detection and quantitation of fluorescent materials. A number of flow cells, incorporating ,a promethium-147 beta particle emitter, were designed and developed with the objective of attaining maximum sensitivity from the detection technique. The response of, the detector to eluted materials, the linearity of the detector response with sample loading and the sensitivity of the detector were examined in normal and reversed phase liquid chromatography. During the development of the BIF detector it became evident that the compounds detected need not be inherently fluorescent. The range of compounds detected could be increased to include those which quench the beta-induced fluorescent emission from the mobile phase. The technique of quenched beta-induced fluorescence was investigated as a detection technique and the response, linearity of response and sensitivity to eluted materials examined. Cerenkov photons are generated whenever a charged particle, travelling at a velocity greater than the velocity of light in the medium, passes through a transparent medium. Cerenkov photons are emitted from the medium as a continuum of wavelength range between 180 nm and 600 nm. The principle of absorption of Cerenkov photons was investigated as a detection technique in liquid chromatography. Strontium-90 was incorporated into a number of flow cells and the response, linearity of response and sensitivity of eluted materials, examined in normal and reversed phase liquid chromatography.

The rhodium speciation in nitric acid has been identified, primarily by the use of 103Rh Nuclear Magnetic Resonance Spectroscopy. The results have indicated that the rhodium species in stored high level waste (HLW) will range from the hexaaquo ion, {Rh(H20)6}3+-to complexes of the general formula {Rh(H20)6-n(NO2)nl(3-n)+, depending on the nitrite ion concentration. The solvent extraction of these complexes by dinonylnaphthalene sulphonic acid and various organo-phosphine sulphides has been investigated, and an integrated scheme for recovering rhodium from HLW is proposed.

14 MeV neutron activation analysis, based on the 82Se(n,2n) Se81m nuclear reaction, has been investigated for the measurement of selenium in environmental waters. The levels of the selenium present in environmental waters and the relatively high limit of detection achievable with fast neutron activation analysis resulted in the need to develop a concentration procedure for the extraction of selenium from large volumes of environmental water before neutron activation.

Tritium labelled compounds are widely used in the physical and life sciences. The preparation of such compounds is a very important area of chemistry. Although the methods are, on the whole, fairly simple and straightforward, there is still a need for improvement. The same applies as far as the analysis of the tritium distribution is concerned. High resolution 3H NMR spectroscopy of solutions is now a well established technique. However many compounds exist as solids which are either insoluble or sparingly soluble in organic solvents, consequently there is a need to develop high resolution 3H NMR spectroscopy of solids. The thesis therefore consists of four chapters. The first is a review dealing with the properties of tritium, the various labelling methods and tritium nuclear magnetic resonance spectroscopy. In the second chapter an account is given of the way in which complex metal tritides and tritiated methyl iodide, an important reagent which enables one to introduce three tritium atoms in a single step and therefore obtain products of very high specific activity, are prepared. In the third chapter an account is given of the synthesis and attempted tritiation of two potential 5-HT re-uptake inhibitors, prior to their use in biological studies. Whilst the synthesis of the two compounds N-[[[l-[(l-bromo-2-naphthalenyl)methyl]-4-piperidinyl]amino]carbonyl]-3-pyridinecarboxamide, and N-[[[l-[(l-bromo-6-fluoro-2-naphthalenyl)methyl] -4-piperidinyl]amino]carbonyl]-3-pyridinecarboxamide, was successful the tritiation procedure led to unforseen difficulties. Finally in the fourth chapter solid state tritium NMR spectroscopy, using a magic angle accessory, was developed and used in the analysis of several tritiated compounds.

A beta spectrometer, consisting of a liquid scintillation counter, coupled to a programmable multichannel analyser was used to achieve the objective of detecting and measuring beta activity in low level aqueous environmental solution as well as identifying the radioisotopes present. Aqueous solutions of standard beta emitters, covering a range of energies between 18.6 KeV and 3550 KeV, were used to develop computer methods for analysis. The best proportions of the counting cocktail was found consist of 4.0 ml of aqueous sample, 3.0 ml of Triton X-100 and 3.0 ml of toluene containing 4.0 g per litre PRO and 0.4 g per litre POPOP. The effects of pH, acids, bases, buffers, and salts on the stability of the mixture and on the detection efficiency of the radioisotopes, were investigated and found not to be severe. Pretreatment of the sample was not required. It was found that temperature changes, beyond the operating temperature range, could result severe errors. 1024 channels of aquisition area, for the collection of the spectra, give good conditions for computer analysis. End channel and channel number of maximum count calibration gave a linear relationship to the Em, of standard beta emitters. It was found that the theoretical fitting of the spectra is possible and the normalisation ratio V of the theoretical to the experimental fitting procedure has alinear relationship to the activity of emitter. Kurie plot was applied for checking the Emav value of the emitters used. Application of the Cerenkov counting technique for beta emitters, gives extra data to support the main results. For the analysis of environmental solutions, which may contain a variety of radioisotopes, the system was used to obtain spectra of alpha emitters, beta emitters with internal conversion and Cerenkov radiation. Synthetic mixtures of tritium and carbon-14 of activity ratios between 8:1 and 1:8 were used to investigate the problems of multielement spectral analysis.

Glassy methanolic and ethanolic solutions of molecular oxygen were exposed to X-rays at 4.2 K. A marked inhibition of the formation of e-t centres together with formation of O2- was observed. The results suggest that the environment of O2 in methanol is such that initial hydrogen-bond transfer to O2- is facile even at 4.2 K. In ethanol, O2- is too far from hydrogen bonded OH groups for this mechanism to operate. Dilute aqueous glassy solutions of the enzyme superoxide dismutase (SOD) were exposed to ?-radiation. Reduction of the native Cu(II) centre to Cu(I) was observed. A reaction was established between this reduced form and O2-. Potassium hexacyanoferrate II was shown to be a suitable chemical reducing agent for SOD after purification, whereas sodium dithionite was shown to modify the copper centre. Study of the disulphide bridge of reduced SCD revealed RSSR- radicals and, in sane cases, species 'X', depending on the nature of the reducing agent. The pH dependence of S(X) and the effect of some anions has been illustrated and serves to confirm documented results. Dilute aqueous glassy solutions of powered haemoglobin and diluted sarrples of whole blood were exposed to ?-radiation. ? and ? subunit haem Fe-O2 centres were identified at 77 K and several spectral changes recorded during warming. Tentative identification of these species has been made.

The aim of this thesis was to develop a molecular imaging probe for the urokinase plasminogen activator (uPA) system, which has been shown to play a critical role in cancer metastasis, tumour aggressiveness and likelihood of progression. Two classes of small molecule inhibitors carrying isotopes of iodine were synthesized and evaluated using in vitro assays and in vivo studies. Lead compounds showed high affinity for the target with Ki values in the low nanomolar range (1b = 1.4 nM, 1e = 6.1 nM, 1g = 2.6 nM and 2a = 2.1 nM). Biodistribution studies of the reversible compounds (1b, 1e, 1g) showed rapid clearance, accumulation in the gall bladder and intestines and little to no tumour uptake (<1 %ID/g). The irreversible inhibitor (2a) showed specificity for the target through SDS-PAGE and biodistribution studies. Analysis of the biodistribution pattern showed retention in the tumour over time reaching a maximum at 24 h post-injection of 1.95 %ID/g with tumour-to-blood ratio being 0.65 at 24 h, 1.13 at 48 h and 1.09 at 96 h post-injection. A parallel strategy reported involved targeting the uPA receptor (uPAR) through the use of antibodies and bioorthogonal chemisty based on radiolabeled tetrazines and transcyclooctene (TCO) functionalized biomolecules. A new tetrazine synthon was developed that can be readily labeled with both 99mTc and 18F where the products were produced in 75 and 31 % radiochemical yields. Stability studies showed the compounds are suitable for use in vivo. Biodistribution studies were carried out in CD1 mice and results showed that both probes had sufficient distribution patterns to warrant use in pre-targeting strategies. Their reactivity with TCO, including functionalized derivatives such as TCO-anti-uPAR, was also demonstrated creating the means to develop PET and SPECT probes for imaging the urokinase system using a single prosthetic group. / Thesis / Master of Science (MSc)

The aim of this thesis was to develop and evaluate albumin-based conjugates for their use in radiotherapy and antibody-recruiting therapy which may then be combined to enhance therapeutic efficacy of each monotherapy. The approach taken in order to achieve high tumour uptake of the conjugates and minimize doses to healthy tissues involved the intratumoural administration of therapeutic compounds; a technique which has gained popularity in recent years for the treatment of solid tumours. Despite the promise this method of administration holds, it is often limited by the fast clearance of injected compounds from the tumour. Using albumin-based conjugates allows for the exploitation of the enhanced permeation and retention (EPR) effect which aids in the retention of the compound at the site of interest for longer periods of time, thus allowing the opportunity for enhanced therapeutic efficacy. Bovine serum albumin conjugated with DOTA chelators was first synthesized and found to possess 3.9 ± 0.4 chelates per BSA molecule. Radiolabelling of the compound with lutetium- 177 produced the desired product in radiochemical yields of 74 ±2 % with a radiochemical purity >99%. The stability of the compound was evaluated by monitoring the radiochemical purity over 7 days which was found to be >95% pure over the entirety of the testing period, indicating a stable product. The intratumoural administration of [177Lu]Lu-DOTA-BSA in a triple negative breast cancer (TNBC) tumour model revealed significant tumour retention of 52 ± 12 %ID/g and 35 ± 6 %ID/g at 24 h and 72 h post-injection, respectively, while autoradiography displayed a heterogenous dispersion of the compound throughout the tumour. A multidosing therapy study in which animals received two doses of either 4.44, 5.92, or 7.40 MBq of [177Lu]Lu-DOTA-BSA showed promise, with a strong trend observed between the administration of higher doses and a prolonged lifespan. Histological analysis of tumours excised 7 days post-treatment revealed signs iv of necrosis and apoptosis in tumours treated with 7.40 MBq [177Lu]Lu-DOTA-BSA. These preliminary results prove to be a promising approach for use in combination therapy and may be further optimized to enhance its efficacy as a monotherapy. Next, the in vivo evaluation of DNP-BSA was carried out to assess using an intratumourally administered, albumin-based platform for antibody-recruiting in a triple negative breast cancer model. A preliminary antibody-recruiting study administering 35 nmol DNP-BSA three times per week unfortunately did not induce slowed tumour growth nor did it have an impact on lifespan. Treated mice were also unable to tolerate repeated doses of the antigen which indicated too high of a concentration and/or dosing frequency was used. A tolerability study was then carried out in order to determine a treatment schedule which did not lead to adverse effects. Mice treated once per week with low (9 nmol) to moderate (17 nmol) doses of DNP-BSA did not display toxic effects but unfortunately did not exhibit a therapeutic effect nor any indication that an adaptive immune response was achieved. These results suggest that further optimization is required prior to use in combination therapy and moderate doses (17 nmol) DNP should be used to investigate a treatment schedule which is able to induce antibody recruitment. / Thesis / Master of Science (MSc)

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