The successful utilization of carbon nanomaterials in future electron spin-based technologies is highly dependent upon the ability to control their assembly at the nanoscale to form tailored solid-state architectures. Spin active metallofullerenes (MFs), Sc@C₈₂ and La@C<sub>82,/sub>, can be self assembled in 3D fullerene crystals or inside a carbon nanotube to form peapod structures. Single walled carbon nanotubes (SWCNTs) are an architect material to potentially allow the formation of 1-D spin chains. SWCNTs should be optimised to allow formation of spin chains and free of magnetic catalyst and carbon impurities, which have previously limited investigations of SWCNT spin properties. To address this, SWCNTs produced by laser ablation with a non-magnetic PtRhRe catalyst were purified through a multiple step centrifugation process in order to remove amorphous carbon and catalyst impurities. Centrifugation of SWCNT solutions resulted in sedimentation of carbon nanotube bundles containing clusters of catalyst particles, while isolated nanotubes with reduced catalyst particle content remained in the supernatant. Electron paramagnetic resonance (EPR) signals were detected only for samples which contained catalyst particles, with the ultracentrifuged SWCNTs showing no EPR signal at X-band (9.4 GHz) and fields ≤0.4 T. Integration of MFs into future devices requires a clear understanding of the nature of the spin and spin-spin interactions. Evaluating the spin properties of MFs, in both 3D (crystals) and 1D (peapods), will identify the spin-spin interactions and the affect of the surrounding SWCNT. Diluting spin active Sc@C₈₂ and La@C₈₂ MFs in a diamagnetic C₆₀ matrix, between 0.4% and 100%, permitted the tuning of the mean fullerene separation and thus interfullerene spin interactions. In dilute concentrations of MFs the hyper ne structure was resolved in EPR and with increasing concentration exchange narrowing was observed as a single narrow EPR peak. Encapsulation of Sc@C₈₂ MFs, of varying dilutions, into purified SWCNTs allowed formation of highly ordered 1-D array of metallofullerenes. Changing the spin environment from 3D crystal to 1D peapod resulted in the loss of the observed hyperfine structure in EPR. A single narrow peak was observed for Sc@C₈₂:C₆₀ peapods, indicating significant affect of the surrounding SWCNT structure upon the spin interactions of 1D metallofullerenes. Peapods of Ce@C₈₂ showed a similar EPR signal, suggesting that the observed narrow peak arises from charge transfer between the MF cage and the surrounding SWCNT.

The development of enzymatic biosensors and enzymatic biofuel cells (EBFCs) has been a significant area of research for decades. Enzymatic catalysis can provide for specific, reliable sensing of target analytes as well as the continuous generation of power from physiologically present fuels. However, the broad implementation of enzyme-based devices is still limited by low operational/storage stabilities and insufficient power densities. Approaches to improving upon these limitations have focused on the optimization of enzyme activity and electron transfer kinetics at enzyme-functionalized electrodes. Currently, such optimization can be performed through enzyme structural engineering, improvement of enzyme immobilization methodologies, and fabrication of advantageous electrode materials to enhance retained enzyme activity density at the electrode surface and electron transfer rates between enzymes and an electrode. In this work, varying electrode materials were studied to produce an increased understanding on the impacts of material properties on resulting biochemical, and electrochemical performances upon enzyme immobilization and an additional method of electroactive enzyme-based optimization was developed through the use of polymer-based protein engineering (PBPE). First, graphene/single-wall carbon nanotube cogels were studied as supports for membrane- and mediator-free EBFCs. The high available specific surface area and porosity of these materials allowed the rechargeable generation of a power density within one order of magnitude of the highest performing glucose-based EBFCs to date. Second, two additional carbon nanomaterial-based electrode materials were fabricated and examined as EBFC electrodes. Graphene-coated single-wall carbon nanotube gels and gold nanoparticle/multi-wall carbon nanotube-coated polyacrylonitrile fiber paddles were utilized as electroactive enzyme supports. The performance comparison of these three materials provided an increased understanding of the impact of material properties such as pore size, specific surface area and material surface curvature on enzyme biochemical and electrochemical characteristics upon immobilization. Third, PBPE techniques were applied to develop enzyme-redox polymer conjugates as a new platform for enzymatic biosensor and EBFC optimization. Poly(N-(3-dimethyl(ferrocenyl) methylammonium bromide)propyl acrylamide) (pFcAc) was grown directly from the surface of glucose oxidase (GOX) through atom-transfer radical polymerization. Utilization of the synthesized GOX-pFcAc conjugates led to a 24-fold increase in current generation efficiency and a 4-fold increase in EBFC power density compared to native GOX. GOX-pFcAc conjugates were further examined as working catalysts in carbon paper-based enzymatic biosensors, which provided reliable and selective glucose sensitivities and allowed a systematic analysis of sources of instability in enzyme-polymer conjugate-based biosensors and EBFCs. The knowledge gained through these studies and the in-depth characterization of an additional layer of optimization capacity using PBPE could potentially enhance the progress of enzymatic biosensor and EBFC development.

Master of Science / Department of Mechanical and Nuclear Engineering / Gurpreet Singh / 3D-printing is a popular manufacturing technique for making complex parts or small quantity batches. Currently, the applications of 3D-printing are limited by the material properties of the printed material. The processing parameters of commonly available 3D printing processes constrain the materials used to a small set of primarily plastic materials, which have relatively low strength and electrical conductivity. Adding filler materials has the potential to improve these properties and expand the applications of 3D printed material. Carbon nanomaterials show promise as filler materials due to their extremely high conductivity, strength, and surface area. In this work, Graphite, Carbon Nanotubes, and Carbon Black (CB) were mixed with raw Acrylonitrile Butadiene Styrene (ABS) pellets. The resulting mixture was extruded to form a composite filament. Tensile test specimens and electrical conductivity specimens were manufactured by Fused Deposition Method (FDM) 3D-printing using this composite filament as the feedstock material. Weight percentages of filler materials were varied from 0-20 wt% to see the effect of increasing filler loading on the composite materials. Additional tensile test specimens were fabricated and post-processed with heat and microwave irradiation in attempt to improve adhesion between layers of the 3D-printed materials. Electrical Impedance Spectroscopy tests on 15 wt% Multiwalled Carbon Nanotube (MWCNT) composite specimens showed an increase in DC electrical conductivity of over 6 orders of magnitude compared to neat ABS samples. This 15 wt% specimen had DC electrical conductivity of 8.74x10−6 S/cm, indicating semi-conducting behavior. MWCNT specimens with under 5 wt% filler loading and Graphite specimens with under 1 wt% filler loading showed strong insulating behavior similar to neat ABS. Tensile tests showed increases in tensile strength at 5 wt% CB and 0.5 wt% MWCNT. Placing the specimens in the oven at 135 °C for an hour caused increased the stiffness of the composite specimens.

A scalable spray processing technique was used to fabricate carbon nanotube (CNT)-based film electrodes and solid-state supercapacitors. The sprayed CNT-based electrodes comprised a randomly interconnected meso-porous network with a high electrical conductivity. Layer-by-layer (LbL) deposition of functionalised and oppositely charged single-wall carbon nanotubes (SWNTs) increased the electrode density and improved charging and discharging kinetics when compared with carboxylic functionalised only SWNT electrodes. The capacitance was further increased to 151 F g-1 at 2 mV s-1 and 120 F g-1 at 100 mV s-1 after vacuum and H2 heat treatments that removed the functional groups, and resulted in a hybrid microstructure of SWNTs and multi-layer graphene sheets from unzipped SWNTs. Flexible solid-state supercapacitors were fabricated by directly spraying multi-wall carbon nanotube (MWNT)-based aqueous suspensions onto both sides of a Nafion membrane and dried. A single cell with MWNT-only electrodes had a capacitance of 57 F g-1 per electrode at 2 mV s-1 and 44 F g-1 at 150 mV s-1. Cells with MWNT/ionomer electrodes showed a higher H+ mobility and a lower charge transfer resistance, and the capacitance increased to 145 F g-1 at 2 mV s-1 and 91 F g-1 at 150 mV s-1. Finally, MWNT/TiO2 nanoparticle/ionomer hybrid electrodes were used in the same solid-state supercapacitor configuration and provided a capacitance of 484 F g-1 per electrode at 5 mV s-1 and 322 F g-1 at 100 mV s-1. A qualitative model of the charge storage mechanism was developed, where TiO2 promoted H+ ions via redox reactions that fed protons into the proton-conducting ionomer coating over the MWNTs (in which the TiO2 was embedded), while electrons were readily conducted through the MWNT scaffold. This solid-state supercapacitor provided both attractive energy (31.8 Wh kg-1) and power (14.9 kW kg-1) densities, where such high energy density is difficult to achieve for MWNTs alone and such high power density is difficult for metal oxides alone, especially in the solid state.

Chronic lower back pain is a major public health problem, with direct and indirect economic costs comparable to those of heart disease, depression and diabetes. In many cases this pain derives from degeneration of the intervertebral disc (IVD), a fibrous, avascular tissue that sits between the vertebrae in the spinal column. A novel treatment approach for this ‘discogenic’ pain is the injection of a hydrogel that hybridises in situ and restores the normal biomechanical function of the disc. While a number of promising materials are currently under development, existing approaches to removing degenerate material from the disc prior to injection are invasive and compromise the structural integrity of the disc. Mechanical fractionation of the tissue using acoustic cavitation generated by high intensity focussed ultrasound (HIFU) has the potential to be non-invasive, and to enhance the effectiveness of the procedure by preserving the outer regions of the disc. The primary goal of this thesis is to investigate the feasibility of this approach. The acoustic properties of the disc were first measured using a modified scanning acoustic microscope. The outer region of the disc, the annulus fibrosus (AF) was found to be highly attenuative compared to the central nucleus pulposus (NP). These measured properties were then used in a simplified two-dimensional model to simulate the shape of the acoustic pressure field within the disc. A configuration using two confocal spherically focussed 0.5 MHz single-element transducers was able to produce a tightly focused field suitable for use in the IVD. As preliminary experiments suggested that high pressure amplitudes were required to initiate cavitation inside the disc, the use of exogenous nuclei to lower this threshold was investigated. A novel class of solid sonosensitive nanoparticles (SNPs) suitable for use in the IVD were developed and characterised. These SNPs comprise a layer of hydrophobic silica particles deposited onto a polystyrene core, and are thought to trap small gas pockets in surface crevices. Coated particles were found to reduce the cavitation threshold significantly in both water and blood, from some 2.0 - 2.5 MPa at 1.067 MHz to below 1.0 MPa. The particles were also found to provide repeatable initiation of cavitation activity during prolonged or repeated exposures, and to exhibit good storage stability, suggesting that they they may be appropriate for use within the IVD. Finally, a combined therapy and monitoring system was designed, built and validated. The system comprised two confocal 0.5 MHz spherically focussed HIFU transducers with central openings, each co-axially aligned with either a single element passive cavitation detector or a 64-element array that could be used for both active and passive imaging. The system was found to be capable of initiating inertial cavitation in the disc at pressures as low as 2.5MPa in the presence of sonosensitive nanoparticles. Use of the array in active mode enables creation of a B-mode image that provides anatomical information on the boundaries of the IVD, whist the same array could be used for passive mapping of acoustic emissions arising fromthe HIFU focus during therapy. Two different exposure regimes were found to be capable of producing sizeable perforations within the NP without significantly damaging the AF, and preliminary investigations were carried out into themechanism of damage. The location and extent of cavitation as seen on passive maps acquired during treatment was found to coincide with the regions of NP fractionation. This confirms that passive acoustic mapping can provide the real-time treatment monitoring necessary to ensure both safety and efficacy of ultrasonic IVD fractionation. Prior to clinical application, a significant amount of further development is required to further validate non-invasive disc fractionation by HIFU and the subsequent steps for minimally invasive disc replacement using injectable hydrogels. The present work has nonetheless demonstrated for the first time that minimally invasive removal of degenerate disc tissue is feasible trough the combined use of sonosensitive nanoparticles and a relatively low-cost therapeutic ultrasound system that provides simultaneous anatomical imaging and real-time treatment monitoring by passive acoustic mapping.

Optical spin readout (OSR) in fullerene-based systems has the potential to solve the spin readout and scalability challenges in solid-state quantum information processing. While the rich variety of chemical groups that can be linked (covalently or not) to the fullerenes opens the possibility of making large and controlled arrays of qubits, optical methods can be used to measure EPR down to a single spin thanks to the large energy of optical photons compared to the microwave ones. After reviewing the state of the art of OSR, for which the diamond NV cen- ters constitute the benchmark, we undertake the study of fullerene-based species for OSR. An optically detected magnetic resonance (ODMR) setup was imple- mented in a commercial EPR spectrometer for this purpose. Each experimental chapter focuses on one of the molecular systems in question: a functionalised C₆₀ fullerene with a phosphonate group (C₆₀-phosphine), porphyrin-fullerene ar- chitectures (weakly, strongly and moderately coupled) and finally erbium-doped trimetallic nitride template (TNT) fullerenes (focusing on ErSc₂N@C₈₀). In the C₆₀-phosphine system, coherent optically detected magnetic resonance (ODMR) in the triplet state has been achieved. Since a large variety of organic and organometallic molecules can be attached to it both via the fullerene cage and the phosponate group, this result makes it a very useful template to study OSR molecules chemically linked to a qubit. In the porphyrin based structures, an intermediate coupling case in the form of a trimer-fullerene host-guest complex is found to allow detection of both the porphyrin and fullerene triplet sates by CW ODMR, which makes organo-metallic complexes a possible coupling route for a qubit to an OSR component. In the TNT fullerene, crystal field mixing makes the Er³⁺ inaccessible by ODMR. However, optical photons cause a mechanical rearrangement of the en- dohedral cluster which in turns impacts on the observed EPR. In particular, the dynamics of this process have been studied for the first time and hint to- wards diffusion kinetics at low pump power. An orientational selectivity has been discovered by using a polarised pump, and the time dynamics indicate the rearrangement of the matrix via difusion on a free volume around the fullerenes. This shows that the endohedral Er³⁺ in ErSc₂N@C₈₀ can probe the environment outside the cage.

This thesis describes the synthesis and anion recognition properties of a variety of interlocked host receptors and the application of metal nanoparticles in the areas of catalysis and sensing. <b>Chapter One</b> introduces the field of anion supramolecular chemistry, with particular emphasis on areas relevant to the research discussed in later chapters. Following this, the synthesis and applications of metal nanoparticles are outlined. <b>Chapter Two</b> details the synthesis of a range of halo-triazolium based rotaxanes and explores the effects of altering both the halogen bond donor atom and degree of preorganisation on the anion recognition properties of the interlocked host system. A halogen bond containing catenane is also prepared and its anion binding properties investigated. <b>Chapter Three</b> initially reports the anion-templated synthesis of a series of neutral pyridine N-oxide axle containing rotaxanes before their ability to recognise anions in aqueous solvent mixtures is studied. Attempts to enhance anion binding through the incorporation of a positive charge into the macrocyclic component of the rotaxane structure are also explored. <b>Chapter Four</b> outlines the preparation of β-cyclodextrin functionalised metal nanoparticles and investigations of their catalytic and sensing properties. <b>Chapter Five</b> describes in detail the synthetic and analytical procedures discussed in chapters two to four. <b>Chapter Six</b> summarises the conclusions of this thesis.

This thesis studies parameters influencing both the performance and stability of solid state sensitized solar cells (ssSSCs). ssSSCs benefit from their low materials and manufacturing processing costs, a consequence of using solution processed materials. However, solution processed materials are often structurally and electronically disordered. By characterizing fully operational ssSSCs and their charge transport properties, this thesis elucidates the factors limiting charge transport and proposes routes towards both improved photovoltaic conversion efficiency and long-term stability. Chapter 2 provides an explanation of the operation of ssSSCs, while Chapter 3 discusses the basic methods used in this thesis. Having set this background, Chapter 4 explores the interaction between atmospheric oxygen and charge doping mechanisms in the organic semiconductors used in ssSSCs. To understand the implications of the findings presented in Chapter 4, a new technique, “transient mobility spectroscopy”, was developed to understand the evolution of balanced charge transport behaviour of disordered semiconductors at different operating conditions in ssSSCs. This technique is presented in full in Chapter 5. The understanding gained in Chapters 4 and 5 suggest that alternative light absorbers with higher extinction coefficients may be beneficial to improving the performance of ssSSCs. Chapter 6 discusses the use of an organometal trihalide perovskite, as light absorber in ssSSCs. Using time resolved techniques, the charge transport and recombination mechanisms in various device architectures are explored, allowing suggestions to be made towards future improvements. Chapter 7 uses the technique presented in Chapter 5 to understand a rapid degradation mechanism of working ssSSCs. Particular focus is placed on the titanium dioxide charge-transporting layer. Building on this newfound understanding, two methods for attaining stable photovoltaic performance are provided, a great step forward for this technology.

The primary aim of this thesis is to explore the immunostimulatory properties of a family of layered, crystalline, inorganic materials known as layered double hydroxides (LDHs). <strong>Chapter One</strong> provides an introduction to relevant aspects of the immune system, and the context for investigating the immunostimulatory properties of inorganic materials in terms of vaccine/adjuvant formulations. The possible mechanisms of action of commercial adjuvant materials are also reviewed, and the structure, synthesis methods and applications of LDHs are discussed. <strong>Chapter Two</strong> details the controlled synthesis and characterisation of LDHs in specific particle sizes. A series of MgAl-CO3 LDHs with precisely controlled particle sizes ranging from 20 to 10000 nm were successfully synthesised, then the techniques used were extended to other compositions to create a panel of LDHs for use in subsequent Chapters. In <strong>Chapter Three</strong>, the responses of monocyte-derived dendritic cells (Mo-DC) to the LDH particle sizes discussed in Chapter Two are assessed in terms of viability, surface molecule expression, and cytokine secretion. A statistical modelling approach using the physicochemical properties of the LDHs as explanatory variables for immune responses was employed to evaluate the validity of the model formulated in the previous work, and to establish if particle size could be used to improve its predictive ability. It was found that strong relationships between LDH particle size and certain Mo-DC responses exist, and that these responses could be predicted with a high degree of accuracy. <strong>Chapter Four</strong> is concerned with the investigation of T cell responses to LDH-stimulated allogeneic Mo-DC. Various methods were used for assessing T cell division and proliferation, and a protocol for intracellular cytokine staining was developed to probe T cell polarisation. Five LDHs, which have elicited potentially interesting T cell responses in previous work, were selected for investigation. However, using the assays described, no discernible improvement in proliferation or polarisation was observed with any of the LDHs tested. <strong>Chapter Five</strong> presents an initial exploration of the interactions between LDH particles and cells. Experiments have shown that LDH particles both adhere to and are internalised by Mo-DC. Variations in the extent of internalisation with both particle size and composition were highlighted by confocal microscopy studies. Through investigations into interactions between LDH particles and the plasma membrane using protease enzymes, it was revealed that adhesion of LDH particles is partly protein-dependent. Further studies have also demonstrated a pH-dependent element to particle association with Mo-DC. Details of the experimental procedures employed are included in <strong>Chapter Six</strong>. Supplementary information referred to in the main thesis may be found in the <strong>Appendices</strong>.

Solid-state dye-sensitized solar cells (ssDSCs) offer the possibility of high power conversion efficiencies (PCEs) of over 20%. However, after more than a decade of research, devices still barely reach over 7% PCEs. In this thesis, limitations to device performance are studied in detail, and solutions for future advancement are put forward. In the first part of the thesis, factors limiting charge generation are explored by studying the crystallization environment of mesoporous TiO2 self-assembled through block copolymers. It was found that the density and distribution of sub band gap states are a function of the synthesis conditions and critically affect the performance characteristics of the self-assembled titania used in ssDSCs. As a result, the self-assembled mesoporous oxide system presented in this thesis outperforms for the first time the conventional nanoparticle based electrodes fabricated and tested under the same conditions, with demonstrated PCEs of over 5%. In chapters 6, 7, and 8, the factors limiting the diffusion length and hence, the thickness of the fabricated devices, are carefully examined. Previous literature points towards insufficient pore-filling of the hole transporting material (HTM) as the main limiting factor. In chapter 6, a pore-filling study is shown where a new technique to evaluate the pore-filling fraction of the HTM in the conventional mesoporous metal oxide electrode is also presented and conclude that sufficient pore-filling of thick films can easily be achieved. Another usual strategy to extend the electron lifetime in the devices and thus, the charge diffusion length, involving thin film coatings of insulating metal oxides is examined in chapter 7, with satisfactory results for SnO2-based ssDSCs. The diffusion length can also be extended if the factors limiting the diffusion of charges through the device are identified and removed, as presented in chapter 8. Finally, a study on the stability of the ssDSC is presented in chapter 9. The developments achieved enable long term stability to be effectively targeted, and represent a key milestone towards commercial realization of ssDSCs.