Background Nanotechnology is an important and promising field that can lead to improved environment and human health and contribute to a better social and economic development. Materials in nanoscale have unique physiochemical properties which allow for completely new technical applications. Enlarged surface area and properties due to quantum physics are among the properties that distinguish the nanoscale. Nano safety has evolved as a discipline to evaluate the adverse health effects from engineered nanomaterials (ENMs). The prevalence of allergic diseases is increasing in the society. An additional issue is the influence of inherited factors on the health responses to ENMs. The aim of this thesis was to investigate the respiratory, inflammatory, and immunological effects following inhalation of ENMs; both sensitive and genetically susceptible individuals were used. Sensitive individuals refer to individuals with pre-existing respiratory diseases, such as allergic asthma, and genetically susceptible individuals refer to individuals prone to autoimmune and allergic diseases. Methods In vivo models of mice and rats were used. In study I the inflammatory and immune responses following exposure to titanium dioxide nanoparticles (TiO2 NPs) were investigated. The effect of when the TiO2 NP exposure occurs during the development of allergic airway inflammation was investigated in study II, with regards to respiratory, inflammatory, and immune responses. In study III, the influence of the genetics on the respiratory, inflammatory, and immune responses, following TiO2 NP exposure to naïve and sensitive rats was evaluated. In study IV, the inflammatory and immune responses of naïve mice and mice with an allergic airway inflammation were studied in lung fluid and lymph nodes draining the airways following inhalation to hematite NPs (α-Fe2O2). Results Exposure to TiO2 NPs induced a long-lasting lymphocytic response in the airways, indicating a persistent immune stimulation. The dose and timing of TiO2 NP exposure affected the airway response in mice with allergic airway disease. When the mice were exposed to particles and an allergen during the same period, a decline in general health was observed. By comparing different inbred rat strains it was demonstrated that genetically determined factors influence the immune and respiratory responses to TiO2 NP exposure in both naïve and sensitive individuals. Exposure to hematite NPs resulted in different cellular responses: naïve mice had increased numbers of cells while mice with allergic airway inflammation had decreased cell numbers in BALF. Analogous cell responses were also observed in the lung draining lymph nodes. Conclusion Altogether, this thesis emphasises the complexity of assessing health risks associated with nanoparticle exposure and the importance of including sensitive populations when evaluating adverse health effects of ENMs. / <p>Forskningsfinansiär: Umeå Center for Environmental Research, and by the Swedish Ministry of Defence</p>

Two synthesis pathways were employed throughout this work to create a variety of unique carbon materials. The first of these routes involves the photo-dissociation of liquids by direct irradiation with ultrashort laser pulses; while the second entails the bombardment of polycrystalline chemical layers by a pulsed laser induced carbon plasma. The pulsed laser irradiation (PLI) of liquid benzene (C6H6) was found to result in the formation of amorphous carbon nanoparticles consisting of clusters of sp2-bonded aromatic rings bridged by sp hybridized polyyne functionalities. In a complimentary experiment, liquid toluene (C6H5CH3) was irradiated under similar conditions leading to the synthesis of a series of free floating methyl capped polyynes, with chain lengths ranging from C10 – C20. The synthesis of polyynes is an active and cutting edge topic in material science and chemistry. In a more complex experiment, solutions of ferrocene and benzene were irradiated by fs-laser pulses resulting in highly ordered mesoscale structures exhibiting four unique geometries; ribbons, loops, tubes, and hollow spherical shells. After a purification process, the higher order structures were destroyed and replaced with nanoparticles consisting of three distinct species including; pure iron, and two phases in which part of the ferrocene molecule was bound to either carbon or iron/carbon complexes. This material is extremely interesting because it exhibits properties similar to that of an electret and is also ferromagnetic over a large temperature range. In the final liquid phase laser irradiation experiment, a new hybrid deposition technique was originated and used to coat stainless steel electrodes with disordered mesoporous nanocrystalline graphite. This method involves the laser induced breakdown of benzene and the subsequent electrodeposition of the resulting carbon ions. Another focus in this work involved the synthesis of a special class of polymer-like carbon nanomaterials using a new method that augments traditional pulsed laser deposition. This technique involves the plasma processing of frozen materials with a pulsed laser initiated graphitic plasma. We call this technique "pulsed laser induced plasma processing" or "PLIPP". Various thin film compositions were created by processing alkane and alkene ices. Finally, in a slight departure from the previous experiments, the effects of carbon ion bombardment on water ice were examined in an effort to understand certain astrophysical processes.

Bottom-up synthesis is increasingly becoming the method of choice for assembling and studying novel nanomaterials. Whereas more traditional top-down methods may lead to mixtures of products and suffer from reproducibility issues, bottom-up approaches offer atomistic control over the material's structure. Bottom-up synthesis can also produce materials that would otherwise be unobtainable with top-down methodologies. Finite substructures of carbon nanotubes (CNTs) are one such example. The work encompassed in this thesis details the study of two related classes of CNT substructures: the cycloparaphenylenes (CPPs) and [5.7]ncyclacenes. Cycloparaphenylenes are a class of graphitic material with many unique properties that make them intriguing candidates for study in a variety of electronic applications. Chapter 1 describes the current state of CPP research, from preliminary synthesis to fundamental understanding of their properties. To optimize device performance, carbon materials are often doped with heteroatoms. Towards this end, the synthesis of a series of nitrogen-doped [8]CPPs (N-[8]CPPs) are detailed in Chapter 2. Nitrogen is incorporated into the CPP structure by way of the reductive aromatization strategy used for the all carbon CPPs, replacing 1,4-dibromobenzene with 2,5-dibromopyridine. The synthesis utilizes oxidatively masked benzenes to assemble less strained, macrocyclic precursors. Through the divergent nature of the synthesis, macrocycles containing up to three nitrogen atoms at precise locations are prepared. Macrocycles are aromatized via a single electron reduction to reveal the final N-CPP structures. Chapter 3 details the full characterization of the properties of the novel N-[8]CPPs. The differences between the N-[8]CPPs and [8]CPP are rationalized in the context of DFT studies. Finally, the study of 1N-[8]CPP and [8]CPP as novel electrode materials in supercapacitor cells is presented. Preliminary results show that the CPP electrodes are more conductive than the activated carbon control group, but the specific capacitances are found to be low. Finally, Chapter 4 describes the computational study of a novel family of macrocycle: [5.7]ncyclacenes. [5.7]ncyclacenes are isomers of the sought after [n]cyclacenes. Unlike their isomeric cousins, DFT studies show that [5.7]ncyclacenes have stable, closed-shell singlet ground states with relatively low strain energies. NICS values also show the molecules to be non-aromatic. These results suggest that with proper synthetic design, the [5.7]ncyclacenes should be accessible synthetically.

<p>Nanocomposite thin films are materials that have the potential to improve and tune many properties for various applications in electronics, sensors, memory storage, and optics. Materials properties are a consequence of their structure, so being able to manipulate the nanostructure of nanocomposite thin films is important for modifying them for device purposes. One structure that has gained a lot of attention is vertically aligned nanocomposites (VANs) due to the increased vertical coupling between two or more phases of materials and the unique nanostructures achievable through controlling deposition factors. </p> <p>VAN thin film growth involves many factors: diffusion, substrate surface conditions, source material composition, and deposition temperature and rate. The two main approaches to thin film fabrication are bottom-up and top-down. Bottom-up growth focuses on the self-assembly of the nanostructure. This work focuses on the self-assembly of VAN thin film materials through controlling the thermodynamic and kinetic factors involved in thin film growth. The main factors being considered in this work are substrate manipulation, oxygen gas flow during deposition, deposition rate, and composition. The effectiveness of each of these methods is evaluated in comparison to each other and their growth of VAN thin film materials along with the future work needed to refine each nanostructure manipulation method. </p>

Nanocellulosics, often found in the form of cellulose nanocrystals (CNCs) and nanofibrillated cellulose (NFCs), provide promise as rheological modifiers and reinforcement fillers for composite materials. The biological origin of CNCs promises a bio-renewable resource with the potential to expedite degradation times compared to synthetic polymer species. Additionally, the surface functional groups provide a route for both hydrogen bonding and further chemical modification. While much research is currently investigating the possible uses of these materials, they offer limited aid if their use is not scalable to industrial processing techniques. Common processing techniques such as injection molding subject materials to high temperatures and strain rates upwards of 100000 s-1. Thermal stability is a known challenge that can be increased via chemical modifications, but little is known about the effects of high or extended shear stresses typical of those experienced during typical polymer processing. High shear rates, which proportionally result in high shear stresses, have the potential to influence the alignment, degradation, and overall usability of these materials when employed in consumer applications. In this work, we investigate the rheology and processing of aqueous CNC suspensions at concentrations up to 12.1 wt% and of aqueous NFC suspensions at concentrations up to 20 wt% under capillary shear stresses. Traditional capillary rheology corrections, including the Weissenberg-Rabinowitsch-Mooney (WRM) correction for non-Newtonian fluids, and the Bagley correction for entrance pressure effects, have been applied to determine the true rheological behaviors of these suspensions. Additional analysis using atomic force microscopy (AFM), wide-angle x-ray scattering (WAXS), and conductometric titration assist identification of morphological and chemical changes that affect the CNMs after they have been subjected to industry-relevant shear rates. These studies demonstrate that processing conditions can significantly affect the size and shape of the post-processed nanomaterials by fracturing the CNCs and unwinding the larger bundles of the NFCs. Given the importance of the final aspect ratio of filler and reinforcement materials, the impact of this discovery will substantially influence how these materials are used and processed to create consumer products. / Doctor of Philosophy / As the world struggles with the problem of plastic waste and climate change, it is important to develop biologically friendly solutions to combat these issues. Filler materials such as carbon fibers and glass fibers can help create lightweight materials for cars and transportation containers. However, carbon fibers can be hazardous and expensive to obtain. Glass fibers offer a more cost-effective option, but they often break during processing and are heavy in comparison to carbon fibers. Cellulose nanomaterials (CNMs) can provide a lightweight and more bio-friendly alternative to these fillers. These CNMs can come from a wide variety of sources, such as hardwood trees, bacteria, or tunicates (a type of marine animal). This makes them abundantly available, relatively cheap to produce, and easy for the environment to break down fully. Using these as fillers instead of glass fibers, carbon fibers or other materials could help reduce much of our waste, but we need to be able to process them in the same ways we currently handle other composite materials. This work focuses on characterizing the effect of high-speed flows and the forces those flows put on the cellulose nanomaterials. The following document will show that the smaller, more rigid, cellulose nanocrystals (CNCs) often break under these stresses, while the longer nanofibrillated cellulose (NFCs) unwind and disperse.

Acid oxidation of multi-walled carbon nanotubes (MWCNTs) introduced carboxylic acid sites onto the MWCNT surface, which permitted further functionalization. Derivatization of carboxylic acid sites yielded amide-amine and amide-urea functionalized MWCNTs from oxidized precursors. Conventional MWCNT characterization techniques including X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and Raman spectroscopy supported successful MWCNT functionalization. Incorporation of MWCNTs functionalized with hydrogen bonding groups into a segmented polyurethane matrix led to an increase in mechanical properties at optimized MWCNT loadings, in contrast with non-functionalized MWCNTs that resulted in mechanical property decreases across all loadings. Dynamic mechanical analysis (DMA) demonstrated an increase in the polyurethane-MWCNT composite flow temperature with increasing hydrogen bonding MWCNT incorporation, as opposed to non-functionalized MWCNT composites which displayed no significant change in flow temperature. Variable temperature Fourier transform infrared spectroscopy (VT FT-IR) probed temperature-dependent hydrogen bonding in the polyurethane-MWCNT composites and revealed a significant impact on composite hydrogen bonding interactions upon MWCNT incorporation, which was amplified in composites formed using hydrogen bonding functionalized MWCNTs. Acid oxidation of carbon nanohorns (CNHs) yielded carboxylic acid functionalized CNHs, providing sites for further reaction with histamine to afford histamine-functionalized CNHs (His-CNHs). Raman spectroscopy, XPS and TGA confirmed successful functionalization. Transmission electron microscopy (TEM) demonstrated that His-CNHs efficiently complex quantum dots (QDs) through imidazole-Zn interactions. Combination of His-CNHs, QDs, and a poly(oligo-(ethylene glycol9) methyl ether methacrylate)-block-poly(4-vinyl imidazole) copolymer using an interfacial complexation technique afforded stable ternary nanocomplexes with average hydrodynamic diameters under 100 nm. These ternary nanocomplexes represent promising materials for photothermal cancer theranostics due to their size and stability. The efficient reaction of 2-isocyanatoethyl methacrylate with amines afforded urea-containing methacrylic monomers, where the amine-derived pendant groups determined the polymer Tg. Reversible addition-fragmentation chain-transfer (RAFT) polymerization enabled the synthesis of ABA triblock copolymers with urea-containing methacrylic outer blocks and poly(2-ethylhexyl methacrylate) inner blocks. These ABA triblocks copolymers displayed composition dependent phase-separated morphologies and desirable mechanical properties. The urea-containing polymers efficiently complexed gold nanoparticles through urea-gold interactions. Furthermore, urea-containing methacrylic polymers served as a useful matrix for incorporation of silica-coated upconverting nanoparticles, affording upconverting nanoparticle composite films.The novel ionene monomer N1,N2-bis(3-(dimethylamino)propyl)oxalamide permitted synthesis of novel oxalamide-containing ammonium ionenes. The hydrogen bonding, charge density, and counter anion tuned the ionene mechanical properties. The ionene structure also influenced water uptake and conductivity. The differences in physical properties correlated well with the morphology observed in small-angle X-ray scattering. The oxalamide-containing ionenes greatly enhance mechanical properties compared to typical ammonium ionenes, and further expand the library of ionene polymers. / Ph. D.

Doctor of Philosophy / Department of Chemistry / Takashi Ito / This research was focused on understanding how external stimuli affect the permeability of the chemically modified electrodes, and how the materials used in modifying the working electrodes respond to the changes in the surface charge. We adopted a voltammetric type electrochemical sensor to investigate the permeability effects induced by pH and organic solvents. The working electrodes used in this research were chemically modified with thioctic acid self assembled monolayer (TA SAM), track etched polycarbonate membranes (TEPCM) and PS-b-PMMA nanoporous films (polystyrene-block-polymethylmethacrylate). We studied the permeability behavior of each of the material upon application of external stimuli. In chapter 3, the permeability changes induced by change in surface charge of thioctic acid SAM was investigated. The surface charge of the monolayer was tuned by changing pH of the medium, which resulted in decrease of redox current of a negatively charged marker due to deprotonation of the surface –COOH groups of TA SAM. Decrease in redox current reflected a decrease in the reaction rate, and by using closed form equations the effective rate constants at several pKa values were extracted. In chapter 4, permeability changes induced by pH in TEPCM were investigated. We assessed the surface charge of these membranes via cyclic voltammetry generated for neutral and charged redox molecules. Limiting current of charged markers were affected by the surface charge induced by pH, where as the redox current for the neutral marker was not affected. Experimental redox currents were larger than the theoretical current, indicating that redox molecules preferentially distributed in a surface layer on the nanopore. Organic solvent induced permeability changes of PS-b-PMMA nanoporous films were investigated via electrochemical impedance spectroscopy and AFM. Higher response of pore resistance in the presence of organic solvents indicated either swelling of the nanoporous film or partitioning of organic solvents in the pores. However AFM data revealed that the permeability changes are due to partitioning of the solvents rather than swelling of the porous film, since there was no appreciable change if the pore diameter in the presence of solvents.

Nanotechnologies are the fastest growing industry sector ever recorded. The US budget for nanotechnology is predicted to reach the 1 trillion dollar threshold in 2015, meaning that nanotechnologies will indeed be larger than all other technologies combined. High aspect ratio nanomaterials (HARN) become increasingly important in the nanotechnology industries, and show great promise, offering many advantages and improvements to a significant range of products. The main feature of HARN is the ratio of the width of a nanomaterial to its height which can be up to 1000, making the material fibre or platelet- shaped. However, this feature leads to comparison between HARN and other high aspect ratio materials including fibre shaped materials, such as asbestos fibres. Due to the structural similarities between fibrous HARN and asbestos the question arises- do HARN pose the same risk as asbestos? This project aimed to assess the potential of a range of HARN to cause similar pathological effects as asbestos fibres. In order to address this aim a panel of HARN was tested against the fibre pathogenicity paradigm in vivo by examining the pulmonary and pleural responses as well as in vitro to reveal the mechanism of cell/HARN interaction. The first part of the study focused on fibre-shaped HARN, including a panel of distinct length classes of silver nanowires (AgNW) which were injected directly into the pleural space, a target tissue for asbestos related diseases. Injection of high aspect ratio AgNW into the pleural space of mice revealed a length dependent inflammatory response in line with the fibre pathogenicity paradigm which explains fibre pathogenicity. AgNW from 5 μm in length and above led to a significant increase in granulocytes in the pleural space which is similar to that seen after treatment with long amosite asbestos. The use of additional HARN with different compositions allowed us to identify a threshold length for fibre-induced pleural inflammation, which is 5 μm. Frustrated phagocytosis has been stated as an important factor in the initiation of an inflammatory response after fibre exposure. A novel technique, backscatter scanning electron microscopy (BSEM), was used to study frustrated phagocytosis since it provides high-contrast detection of nanowires, allowing clear discrimination between the nanofibres and other cellular features. Using this technique we showed that the onset of inflammation does not correlate with the onset of frustrated phagocytosis, with a fibre length of ≥5 μm and ≥10 μm, respectively, leading to the conclusion that intermediate length fibres fully enclosed within macrophages as well as frustrated phagocytosis are associated with a proinflammatory state in the pleural space. We further showed that fibres compartmentalise in the mesothelial cells at the parietal pleura as well as in inflammatory cells in the pleural space. To investigate the mechanism of the lengthdependent inflammation caused by AgNW, the NALP3 inflammasome activation pathway was studied in vitro, however no clear correlation could be identified. We further aimed to investigate the threshold length of fibre-induced inflammation in the lung and the effect of fibre length on macrophage locomotion in an in vitro macrophage migration assay. Pharyngeal aspiration of AgNW resulted in a length dependent inflammatory response in the lungs with threshold at a fibre length of 14 μm. Shorter fibres including 3, 5 and 10 μm elicited no significant inflammation. This identified threshold length differs from that in the pleural space which may be explained by differences in clearance mechanism of deposited fibres from the airspaces compared to the pleural space. Particle clearance from the lung is partly performed by migration of particle-laden macrophages to the mucociliary escalator. We investigated if uptake of longer fibres leads to restricted mobility and showed that exposure to AgNW in the length of ≥ 5 μm resulted in impaired motility of macrophages in the wound closure assay. The second part of the study focused on HARN in the form of nanoplatelet-shaped particles since nanoplatelets may pose an unusual risk to the lungs and the pleural space because of their aerodynamic properties. We first derived the respirability of graphene nanoplatelets (GP) from the basic principles of the aerodynamic behaviour of plate-shaped particles which allowed us to calculate their aerodynamic diameter. This showed that the nanoplatelets, which were up to 25 μm in diameter, were respirable and so would deposit beyond the ciliated airways following inhalation. We therefore utilized models of pharyngeal aspiration and direct intrapleural installation of GP, as well as an in vitro model, to assess their inflammatory potential. These large but respirable GP were inflammogenic in both the lung and the pleural space at an acute timepoint although they decreased in their inflammatory potential over a 6 weeks period. Oxidation of GP in the lung tissue was investigated in order to identify if GP degraded over the 6 week period in the lung tissue and therefore showed reduced inflammogenicity. Raman spectroscopy was used to measure the oxidation state and revealed that no change occurred over the observed timeframe. The mechanism underlying acute GP inflammation was studied in THP-1 macrophages exposed to GP. These investigations showed that GP exposure led to significant expression of IL-1β, which could be blocked via a number of inhibitors related to the NALP3 inflammasome activation. This study highlights the importance of shape/length of HARN as a driver for in vivo and in vitro inflammogenicity by virtue of their respirable aerodynamic diameter, despite a considerable 2-dimensional size which leads to an inflammatory response when deposited in the distal lungs and the pleural space. The identification of the threshold length for nanofibre-induced pathogenicity in the pleura and the lung has important implications for the understanding of the structure–toxicity relationship for asbestos-induced mesothelioma. It also contributes to risk assessment by offering a template for production of safer synthetic nanofibres by the adoption of a benign-bydesign approach. The results of this work highlight the importance of testing new HARN to protect workers in nanotechnology industries and the public.

DNA cages are polyhedra self-assembled from synthetic oligonucleotides in a one-pot process. The main system described in this thesis is a reconfigurable, wire-framed DNA tetrahedron in nanometre-scale. On one of its vertices this tetrahedron has an overhang that can hybridise with a specific sequence of nucleic acids and open the cage. We describe the design of a reconfigurable cage that remained closed under physiological conditions and only opened in the presence of an appropriate signal in solution. Fluorescence techniques were employed to distinguish the open and closed states of the cage. We used flow cytometry and confocal microscopy to successfully established the open and closed states of the cage inside live cultured mammalian cells. Further experiments revealed that the DNA cage could be opened by a separately transfected signalling strand. Hybridisation between two separately transfected systems was possible. The DNA cage was then simplified to a DNA duplex so that the intracellular interactions between the two nucleic acids systems could be studied more efficiently. Microscopy images showed that the interaction occurred in membrane-bound compartments. We describe an investigation into the use of various cellular RNAs, including full-length mRNA and tRNA-RNA fusion, to actuate the DNA cages. Choosing an appropriate cellular opening signal remains a challenge. Analysis showed that bulky cellular RNA experienced steric hindrance with the rigid DNA cage. Finally, other potential biological applications of DNA cages, such as using DNA nanostructures as the carriers for genetic therapeutic agents, were also presented.

Diabetic foot ulcers (DFUs) are a common and severe adverse event associated with diabetes, as 25% of diabetic patients will experience DFUs. The lack of effective DFU therapies results in 20% of diabetic patients requiring amputation. We first developed an algorithm to account for polydispersity when calculating nanoparticle concentration, which will reduce variability between batches and treatments. We also developed a novel 2-layer biomaterial, which combines anti-microbial properties of CLKRS peptide coated silver nanoparticles (CLKRS- AgNPs) with a pro-regenerative collagen matrix embedded with microscopic skin tissue columns (MSTC), to promote DFU wound healing. The collagen hydrogel formulation was optimized, and the physical properties, biocompatibility, and wound healing properties were assessed. Our results indicate that the CLKRS-AgNPs prevent bacterial growth and the collagen matrix provides a regenerative environment. Last, we developed and tested antimicrobial fabrics which can also be applied to chronic wounds, such as DFUs, to prevent and treat infections.