A brief introduction to solid lipid nanoparticles (SLN) is provided and the reasoning behind the use of SLN over other colloidal carriers, such as emulsions and liposomes, are discussed. SLN has many advantageous such as controlled drug release, non-biotoxicity of the carrier, increased bioavailability of drug and lower overall cost. Techniques for the production of SLN, drug incorporation, loading capacity and drug release mechanisms are reviewed. The potential of SLN in anti-cancer drug delivery systems is highlighted. SLN formulations of two different lipids (tristearin, stearic acid), used as carriers for the encapsulation of the anticancer drug substance curcumin (CRC), have been investigated. The physicochemical characteristics of the CRC-SLNs were investigated by particle size, zeta potential and stability measurements. In addition transmission electron microscopy was used to study the morphology of the SLNs and differential scanning calorimetry (DSC) as well as X- ray diffraction (XRD) were used to evaluate the physical state of the drug in the SLN formulations after freeze drying. The release pattern of CRC-SLN showed sustained release over five days, Moreover, encapsulation efficiency at the range of 92-95% indicated the loosely ordered crystal lattice of lipid matrix, which facilitated a higher drug payload. The anti-cancer effects of CRC encapsulated SLN formulations (both loaded and unloaded) were evaluated using a human prostate cancer cell line (LNCaP). Blank SLN (BL-SLN) did not show any anti-tumour activity; CRC encapsulated SLN (CRC-SLN) displayed anti-tumour activity. Both lipid based CRC loaded SLNs reduced the LNCaP cell viability to almost 0% at a CRC concentration of 100 μg/ml. Cellular uptake studies confirmed the internalisation of CRC-SLN which was found to be localized in the cytoplasm around the nucleus. Flow cytometric studies confirmed the early and late apoptosis inducing ability of CRC-SLNs. Retinoic acid (RTA) loaded SLN, optimized by tuning the process parameters (pressure and temperature) and using various lipid grades to produce nano-dispersions, displayed enhanced anticancer activity. The RTA-SLN dispersions were produced by high-pressure homogenization and characterized in terms of particle size, zeta potential, drug entrapment efficiency, transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and in vitro drug release. Anticancer efficiency was evaluated by incubating RTA-SLN with LNCaP cells, and demonstrated reduced cell viability with increasing drug concentrations (9.5% at 200 ug/ml) while blank SLN showed negligible cytotoxicity. Cellular uptake studies of SLNs showed localization within the cytoplasm of the cell and flow cytometry analysis showed an increase in the fraction of cells expressing early apoptotic markers, suggesting that the RTA-SLN is able to induce apoptosis in LNCaP cells. Both empty and loaded (curcumin) nanostructured lipid carriers (NLC) were characterized in relation to their size, zeta potential and polydispersity index. The drug entrapment efficiency and in vitro drug release behaviour of these NLC formulations were also investigated. Analysis of the shape and morphology (using transmission electron microscopy (TEM) and laser diffraction) revealed spherical shaped NLC with a uniform particle size distribution. Cellular uptake studies revealed the internalisation of CRC-NLC, which appear to be localized in the cytoplasm around the nucleus. Flow cytometry studies were performed to evaluate apoptosis inducing abilities of CRC-NLC, as at a CRC concentration of 100 μg/ml, the CRC-NLC treated cells showed 12.2% (early) and 76.9% (late) apoptotic cells. Nude mice bearing prostate cancer xenografts exhibited significant suppression upon administering CRC loaded NLC formulations, with no significant weight loss. The efficacy of CRC-NLC treatment group with CRC only group in comparison with the CRC group showed 40% tumour volume suppression. Unconjugated SLN were conjugated with transferrin for specific (active) delivery of CRC into LNCaP prostate cancer cells. SLNs prepared by high-pressure homogenization were characterised for particle size, zeta potential and drug loading. The transferrin conjugated to SLN was quantified by the Bradford assay. In vitro and in vivo studies of SLN for passive and active delivery of CRC to LNCaP prostate cancer cells were evaluated. In vivo studies of tumour regression efficiency showed CRC-SLN formulations to be more effective in suppressing tumour growth compared to the free drug. In addition the transferrin conjugated SLN also demonstrated a higher anti-tumour activity in tumour bearing mice compared to the non-conjugated formulation. The tumour mass was significantly suppressed by 61% and 79% for CRC-SLN and Tf-CRC-SLN, respectively, when compared with the control group.

No description available.

A great deal of the remarkable properties of plants lie in the complex nature of adhesion of cells which is unparalleled in modern materials science. The exact nature of the polymer network that results in this is still to be completely understood. A basic view of the plant cell wall has a cellulose microfibrillar network embedded in a highly crosslinked pectin matrix. It is suspected that it is these crosslinks that give rise to the adhesion between cells and it is the aim of this thesis to examine the molecular features responsible for inter cellular adhesion in plants and how these might vary within the cell and between cells. A variety of cell separation techniques were utilised including the development of a multi-step pectin extraction procedure and investigation into the use of enzymes to break specific linkages in order to effect cell separation. These experiments confirmed that crosslinks between pectic polymers were responsible for cell adhesion as breaking them resulted in separation. These experiments also showed that the mechanism responsible for cell adhesion differed between faces of the individual cell and also between different types of cell. The existence and potential role in cell adhesion for non-methyl esters was also investigated. From this work it was discovered that non-methyl intermolecular esters existed. Studies that combined enzyme treatment with tensile strength testing equipment at the Institute of Food Research, Norwich endeavoured to test the strength of cell-cell adhesion and these discovered that this varied according to the structure of the polysaccharides in the wall.

Research was conducted to evaluate the potential of chitosan, a fishery waste-based material, and its derivative cross-linked chitosans, as soil amendments for the remediation of metal contaminated land. This research comprised modification of chitosan followed by a characterisation study, a batch sorption study, two pot experiments and a biodegradation study. Chitosan was modified with three cross-linking reagents, namely glutaraldehyde (GLA), epichlorohydrin (ECH) and ethylene glycol diglycidyl ether (EGDE). The characterisation study used X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR) methods to investigate the effect of cross-linking treatment on the surface and physical properties of chitosan, the effect of metal interaction on the surface properties of chitosan and cross-linked chitosans, and the binding mechanism(s) of metal ions onto the chitosans. Cross-linking treatments on chitosan enhanced its chemical stability in acidic media and increased its BET surface area. Metal interaction reduced the crystallinity and changed the surface morphology of the chitosans. FTIR analysis revealed that the complexation of metal ions was through dative covalent interaction with the amino and hydroxyl groups of the chitosans. The batch sorption study evaluated the ability of chitosan and cross-linked chitosans to bind heavy metals. The effects of contact time, initial metal concentration and background electrolyte on metal binding were assessed. The binding behaviour was described by several kinetic and isotherm models. The maximum binding capacity (Q) values, estimated using the Langmuir isotherm model for the chitosans were comparable with other low-cost sorbents reported in the literature. The sorption-desorption study showed that the chitosans were able to retain metal ions on their surfaces, even at dilution factor of x11. The pot experiments evaluated the effectiveness of chitosan and chitosan-GLA in immobilising heavy metals in the contaminated soil. Their effects on plant growth and metal accumulation in plant tissue were determined using Lolium perenne (perennial ryegrass) and Brassica napus (rapeseed). For perennial ryegrass, the results were dependent on the rate of addition of the chitosans. Low application rates (up to 1% w/w) resulted in an increase in metal uptake, whereas 10% (w/w) addition decreased metal uptake. For rapeseed, metal uptake was decreased at all rates of application of chitosans. The ammonium acetate extractable metals in soil decreased following application of chitosan and plant growth. The biodegradation study measured microbial breakdown of the chitosans in both non-contaminated and contaminated soils. It was estimated that a longer period is required to complete the breakdown of the cross-linked chitosans (up to approximately 100 years) than unmodified chitosan (up to approximately 10 years). The influence of biodegradation on the bioavailable fraction of heavy metals in soil was studied concurrent with the biodegradation trial. It was found that the binding behaviour of chitosan for heavy metals in soils was not affected by the biodegradation process.

The asbestinins are a sub-class of the ether bridged 2,11-cyclised cembranoid family of marine natural products that have been isolated from octocoral species Briareum Asbestinum. They exhibit high structural complexity and a diverse range of bioactivities that include cytotoxicity against tumour cell lines, potent anti-bacterial properties and antagonism of both histamine and acetylcholine. This report presents the continued efforts in developing an efficient synthetic route to the asbestinins which will be general enough to enable the synthesis of virtually every member of this family of compounds. The key synthetic steps include; a samarium diiodide reductive cyclisation to generate 2,6-syn-5,6-anti tetrahydropyranol motif, oxonium ylide formation with subsequent [2,3]-sigmatropic rearrangement of a functionalised diazoketone and an intramolecular Diels-Alder cycloaddition to construct the cyclohexyl ring. Many studies have been carried out on other sub-classes within the ether bridged 2,11-cyclised cembranoid family of natural products, of particular interest have been the sarcodictyins and cladiellins, the latter of which has been extensively investigated within the Clark group.

There is currently much interest in the investigation of dynamics in solids and the primary goal of this thesis is to present well-known and new NMR methods used for studying motion on Larmor and spectral timescale. The quadrupolar interaction usually dominates solid-state NMR spectra of quadrupolar nuclei. When the magnitude of quadrupolar interaction is large then the second-order correction to the dominant Zeeman Hamiltonian must be considered. Owing to this second-order quadrupolar effect, NMR peaks can be displaced from their chemical shift positions by a second-order shift. When considering motional averaging of the second-order shift, the critical frequency is the Larmor frequency, 0. In the case of motion that is faster than the Larmor precession, the isotropic quadrupolar shift is affected. This analogous phenomenon in solution-state NMR is known as the "dynamic shift". In Chapter 4, it will be shown that multiple-quantum NMR measurements of isotropic second-order quadrupolar shifts are a simple way to probe nanosecond timescale motions in solids. An analysis of one- and two-dimensional 11B MAS NMR spectra of three isomers of the closo-carboranes gives the results that provide the first evidence for the presence of solid-state dynamic shifts. There are several experiments that provide a sensitive test for the presence of dynamics on spectral timescale. One piece of evidence for dynamics on the spectral timescale is a motional broadening of quadrupolar satellite-transition spinning sidebands. Therefore, it is possible to investigate the influence of dynamic reorientation on satellite-transitions MAS spectra by recording variable-temperature one-dimensional spectra with wide spectral width or by comparing two-dimensional STMAS spectra with MQMAS spectra. These methods can be extended to 2H NMR spectroscopy as the sidebands observed in the magic angle spinning (MAS) NMR spectrum of a spin I = 1 2H nucleus may be very strongly broadened due to interference between the line-narrowing effects of MAS and the dynamics-driven reorientation of the 2H quadrupole tensor, if motion is present in the solid. In the last chapter, the 27Al, 31P and 2H NMR study of AlPO-34 type materials with the topology of chabazite are undertaken and the use of the full range of NMR methods to develop a structure and dynamic behaviour of these materials is presented. In addition, the NMR calculations are performed in order to combine DFT calculations with experimental data. Finally, GaPO-34 samples were investigated to extract information about the effects of Ga substitution in AlPO-34 on dynamical behaviour.

No description available.

In the industrial synthesis of 4,4’-methylene diphenyl diisocyanate (MDI), an unwanted side reaction between the product and the starting material, 4,4’-methylene dianiline, can lead to the formation of ureas. It has been postulated these ureas undergo further reaction with phosgene to produce a precursor to chlorine radicals, which could then attack the MDI backbone forming conjugated systems that would promote colour in the final products. To investigate this process model compounds including 4-benzylaniline (4-BA) and 1,3-diphenylurea were used as starting materials. The reactions carried out showed the phosgenation of the urea forms a chloroformamidine-N-carbonyl chloride (CCC) which upon heating > 303 K can break down to form an isocyanide dichloride (ID). Conventional synthesis routes were used to gain high yields of p-tolyl and phenyl isocyanide dichlorides in order to analyse the compounds. It was found that upon heating to 453 K or irradiating the isocyanide dichlorides in the process solvent (chlorobenzene) coloured solutions were formed; with the presence of MDI and oxygen increasing the intensity of the colouration. Electron paramagnetic resonance spectroscopy was used to gain information on the use of isocyanide dichlorides as a source of chlorine radicals. Using N-tert-butyl--phenylnitrone (PBN) as a spin trap, an 8 line spectra relating to the chlorine adduct was measured confirming the production of Cl•. Throughout the project side reactions involving the formation of carbodiimide from CCC and a secondary route for the phosgenation of the urea to the isocyanate have been investigated and are presented within a global reaction scheme. It was also found the ureas were only partially soluble in the process solvent leading to research into the structure of three different urea molecules and the proposal of a modified reaction scheme.

1,2-Dichloroethane (EDC) plays a major role as an intermediate in the PVC chain and as a feed material for C2 solvent manufacture. Knowledge and understanding at the fundamental level of the role of trace inorganic species present during EDC manufacturing are very limited. The primary aim of this work was therefore to determine the roles of these species. Due to the lack of, and in certain cases contradictory, literature it was important to re-examine the system at its most fundamental levels. The reaction medium in which EDC is produced contains several different organic and inorganic constituents. The most important are 1,2-dichloroethane (present not only as the reaction product but also the solvent), ethane, dichlorine, hydrogen chloride, ethyl chloride, water and iron amongst others (a full description of reaction constituents is provided in chapter 1). The current work has established the presence of [FeCl4]- as the dominant species in solution. Importantly, a precursor to this species has also been identified in dilute and purer/dryer EDC/FeCl3 solutions. This precursor is believed to take the form of a molecular species such as FeCl3.χH2O (χ = 1,2 etc.). The work has also established that the EDC/FeCl3 solution system is inevitably complicated by the presence of FeCl3. This is particularly important when the behaviour of "free" water within the system is examined. The work has established that addition of H2O and/or HCl leads, with time, to the formation of a significant, probably water-related, species in the observed in the infra-red spectrum. A simple model is proposed to account for events occurring at the solid/solution interface.

The objective of this research was to develop and investigate a number of flavoenzyme model systems which were designed to mimic the microenvironment created by the natural apoenzyme’s active site and which would ultimately lead to controlling the redox properties of the flavin cofactor. In natural flavoenzymes the same cofactor is known to catalyze a wide range of reactions according to the interactions involved in stabilizing the three main flavin redox states; the neutral flavin oxide Flox, the flavin radical anion and the fully reduced neutral flavin FlredH2. Previous work reported within the group had focused on simple but effective small molecule solution model systems to isolate and probe these properties. This next generation of model systems employed a combination of general synthetic and polymerization techniques to firstly create synthetic flavoenzymes which were water soluble and therefore able to exist in solution phase under physiological conditions and secondly to utilize recently developed controlled molecular motion techniques as a novel method of interacting and modulating the cofactors behaviour. This thesis was therefore incorporated under two broad heading, “Polymeric flavoenzyme model systems” and “Controlled molecular motion”, both of which share a common flavin theme.