Over 500 million people worldwide suffer from disease associated with intestinal inflammation, including gastric cancer, inflammatory bowel disease, h. pylori infections, and numerous viral and bacterial infections. Although potentially effective therapeutics exist for many of these pathologies, delivery challenges thwart their clinical viability. The objective of this work was to develop drug delivery platforms that could target toxic immunomodulatory therapeutics to diseased intestinal tissues. To meet this objective, we developed an oral delivery vehicle for siRNA and an NF-κB inhibiting nanoparticle that reduces drug-resistance. Small interfering RNA (siRNA) represents a promising treatment strategy for numerous gastrointestinal (GI) diseases; however, the oral delivery of siRNA to inflamed intestinal tissues remains a major challenge. In this presentation, we describe a delivery vehicle for siRNA, termed thioketal nanoparticles (TKNs), that can orally deliver siRNA to sites of intestinal inflammation, and thus inhibit gene expression in diseased intestinal tissue. Using a murine model of ulcerative colitis, we demonstrate that orally administered TKNs loaded with TNFα-siRNA (TNFα-TKNs) diminish TNFα messenger RNA (mRNA) levels in the colon and protect mice from intestinal inflammation. Activation of nuclear factor-κB (NF-κB) results in the expression of numerous prosurvival genes that block apoptosis, thus mitigating the efficacy of chemotherapeutics. Paradoxically, all conventional therapeutics for cancer activate NF-κB, and in doing so initiate drug resistance. Although adjuvant strategies that block NF-κB activation could potentiate the activity of chemotherapeutics in drug resistant tumors, clinical evidence suggests that current adjuvant strategies also increase apoptosis in non-malignant cells. In this presentation, we present a nanoparticle, formulated from a polymeric NF-κB-inhibiting prodrug, that target the chemotherapeutic irinotecan (CPT-11) to solid tumors, and thus abrogates CPT-11-mediated drug resistance and inhibits tumor growth. In order to maximize the amount of NF-κB inhibitor delivered to tumors, we synthesized a novel polymeric prodrug, termed PCAPE, that releases the NF-κB inhibitor caffeic acid phenethyl ester (CAPE) as its major degradation product. Using a murine model of colitis-associated cancer, we demonstrate that when administered systemically, CPT-11-loaded PCAPE-nanoparticles (CCNPs) are three time more effective than a cocktail of the free drugs at reducing both tumor multiplicity and tumor size.

Biodegradable, edible wheat gluten films offer a renewable alternative to plastic food packaging or can be incorporated directly in the food product. Wheat gluten is a good option because it forms a fibrous network, lending strength and elasticity to films. The goal of this research project was to produce, with a water-based film formulation and methodology, smooth, homogeneous wheat gluten films with low water vapour permeability (WVP). The water-based film formulation also served to compare the FT Wonder wheat cultivar, grown in Ontario, to commercially produced wheat gluten and determine the effect of wheat source on the film properties, surface morphology, surface hydrophobicity, WVP, and film swelling in water for different pH, temperature and casting surface conditions. Fluorescence, SPR, and casting formulation viscosity provided preliminary information on the mechanism of film formation and on gluten protein structure induced by modifying the film formulation. This research provides an alternate use for some Ontario wheat cultivars based on their properties in films compared to commercial sources of gluten. As a result, using Ontario cultivars to prepare gluten film packaging material has potential as an alternate source of income for Ontario farmers. This research also defines the film properties for gluten films produced from aqueous solutions, helping to identify processing parameters that could bring gluten films on par with plastic packaging and make gluten films a viable alternative food packaging material. Finally, it was determined that the water vapour permeability of wheat gluten films was not correlated to film surface contact angle.

A study on application of combinatorial methods (CM) and high-throughput methods (HTM) to biomaterials design, characterization, and screening are reported in this thesis - focusing on screening the effects of biomaterial surface features on adherent bone cell cultures. Polymeric biomaterials were prepared on two-dimensional combinatorial libraries that systematically varied the size and shape of chemically-distinct microstructural patterns - generated from blends of biodegradable polyurethanes and polyesters. Characterization and screening were performed with high-throughput optical and fluorescence microscopy. A unique advance of this work is the application of data mining techniques to identify the controlling structural features that affect cell behavior from among the myriad variety of metrics from the microscope images. The results from this study demonstrated the potentials of CM/HTS to be applied to exploratory studies involving complex systems in life sciences. This study accomplishes the goal to demonstrate the efficient screening and exploration of vast and complex dataset, extracting important and meaningful information to narrow down the future path of study in this field. Further study aimed to tuning cellular responses via signals from surface cues will be necessary to examine the causal relationships beyond the observed correlations shown in this exploratory study. It is recommended for further studies to narrow down the range for surface patterning around each of the three 'activation' ranges found in this study: apoptotic, viable, and one unknown state to be studied further. Different cellular-function staining methods will be necessary to be used in cellular imaging techniques in order to explore this unknown state further.

<p>Wood plastic composite (WPC) materials have seen a continuous market growth worldwide in the last decade. So-called extruded WPC profiles are today mainly used in outdoor applications, e.g. decking, railing and fencing. In outdoor conditions, moisture sorption in the wood component combined with temperature induced movements of the polymer matrix causes deformations of such composites. On the macroscopic scale this may lead to unacceptable warp, cup and bow of the WPC products, but on a microscopic scale, the movements will cause interfacial cracks between the particles and the matrix, resulting in little or no ability to transfer and re-distribute loads throughout the material. Moisture within the composite will also allow fungi and micro organisms to attack the wood particles.</p><p>The conceptual idea of this work is to use a chemically modified wood component in WPCs to enhance their long term performance. These chemically modified wood particles exhibit reduced susceptibility to moisture, resulting in better dimensional stability and a higher resistance to biological degradation as compared to that of unmodified wood. The objective of this thesis is to study the effects of using modified wood in WPCs on their moisture sorption behaviour, micromorphology and microbiological durability. The modification methods used were acetylation, heat treatment and furfurylation.</p><p>Equilibrium moisture content (EMC) and sorption behaviour of WPCs were determined by water vapour sorption experiments. The use of thin sections of the composites enabled EMC to be reached within a comparably short time span. The micromorphology was studied by LV-SEM (low vacuum-scanning electron microscope) using a specially designed sample preparation technique based on UV laser. The biological durability was evaluated by laboratory fungal test methods.</p><p>The moisture sorption experiments showed lower moisture levels for all the composites when modified wood particles were used. This was also reflected in the micromorphological studies where pronounced wood-plastic interfacial cracks were formed due to moisture movement in the composites with unmodified wood particles. The sample preparation technique by UV laser proved to be a powerful tool for preparing surfaces for micromorphological studies without adding mechanical defects caused by the sample preparation technique itself. Results from the durability test showed that WPCs with modified wood particles are highly resistant to decay by fungi.</p>

<p>Improving the functionality and reducing revision rates are important driving forces in the development of orthopaedic implants. FibMat is a fibrinogen based matrix developed towards commercialisation by the company Optovent AB. This matrix can be coated on implants and act as a local drug delivery system for bisphosphonates (BPs). BPs are drugs inhibiting bone resorption, and applied with FibMat to improve stability of implants in bone, e.g. when fixing bone fractures. In this thesis, FibMat loaded with BP (FibMat/BP) was coated on stainless-steel screws and titanium screws in order to investigate some technology properties relevant to its clinical applicability. Bone-mimicking materials were used to study scrape-off effect upon insertion. The coagulation properties of fibrinogen as well as the structural properties of BPs were studied after exposure to gamma radiation.</p><p>The screws were coated with FibMat and BP (alendronate and 14C-alendronate) using standard coupling techniques. The total amount and distribution of BP after insertion was measured by liquid scintillation and autoradiography. Coagulation assays were performed in order to determine the coagulation properties of fibrinogen, exposed to doses up to 35 kGy, mixed with thrombin. The structural properties of four different BPs (alendronate, pamidronate, zoledronate and ibandronate), exposed to doses up to 35 kGy were analysed by transmission infrared spectroscopy.</p><p>The results show that FibMat/BP coating on porous stainless-steel screws is virtually unaffected by insertion into bone materials. The anodised, planar titanium screws are more affected by the insertion process, but an even BP distribution in the cancellous material is indicated. The coagulation assays show that gamma-irradiated fibrinogen has a slower coagulation process compared to non-irradiated fibrinogen and form interrupted network unable to clot. The chemical structures of the BPs seem unaffected by exposure to gamma irradiation. In conclusion, the FibMat/BP is a promising technology for local distribution of BP in conjunction with bone implants.</p>

Calcific aortic valve disease (CAVD) is associated with significant cardiovascular morbidity. While late-stage valve disease is well-described, there remains an unmet scientific need to elucidate early pathobiological processes. In CAVD, pathological differentiation of valvular interstitial cells (VICs) and lesion formation occur focally in the fibrosa layer. This VIC pathological differentiation has been shown to be influenced by matrix stiffness in vitro. However, little is known about the focal layer specific mechanical properties of the aortic valve in health and disease and how these changes in matrix moduli may influence VIC pathological differentiation in vivo. In this thesis, micropipette aspiration (MA) was shown to be capable of measuring the mechanical properties of a single layer in multilayered biomaterial or tissue such as the aortic valve, if the pipette inner diameter was less than the top layer thickness. With MA, the fibrosa of normal porcine aortic valves was significantly stiffer than the ventricularis; stiffer locations found only within the fibrosa were comparable to stiffnesses shown in vitro to be permissive to VIC pathological differentiation. Early CAVD was induced in a porcine model, which developed human-like early CAVD lesion onlays. Extracellular matrix remodeling occurred in the absence of lipid deposition, macrophages, osteoblasts, or myofibroblasts, but with significant proteoglycan-rich onlays and chondrogenic cell presence. These early onlays were softer than the collagen-rich normal fibrosa, and their proteoglycan content was positively correlated with Sox9 chondrogenic expression, suggesting that soft proteoglycan-rich matrix may be permissive to chondrogenic VIC differentiation. The findings from this thesis shed new light on early disease pathogenesis and improve the fundamental understanding of aortic valve mechanics in health and disease.

In vivo, adipose tissue demonstrates only a limited capacity for self-repair, and the long-term treatment of subcutaneous defects remains an unresolved clinical problem. With the goal of regenerating healthy tissues, many tissue-engineering strategies have pointed to the potential of implementing three-dimensional (3-D), cell-seeded scaffolds for soft tissue augmentation and wound healing. In particular, microcarriers have shown promise as both cell expansion substrates and injectable cell-delivery vehicles for these applications. However, limited research has investigated the engineering of tissue-specific microcarriers, designed to closely mimic the native extracellular matrix (ECM) composition. In this work, methods were developed to fabricate microcarriers from decellularized adipose tissue (DAT) via non-cytotoxic protocols. Characterization by microscopy confirmed the efficacy of the fabrication protocols in producing stable beads, as well as the production of a microporous surface topography. The mean bead diameter was 934 ± 51 μm, while the porosity was measured to be 29 ± 4 % using liquid displacement. Stability and swelling behavior over 4 weeks indicated that the DAT-based microcarriers were effectively stabilized with the non-cytotoxic photochemical crosslinking agent rose bengal, with only low levels of protein release measured within a simulated physiological environment. In cell-based studies, the DAT-based microcarriers successfully supported the proliferation and adipogenic differentiation of human adipose-derived stem cells (hASCs) in a dynamic spinner flask system, with a more favorable response observed in terms of adhesion, proliferation, and adipogenesis on the DAT-based microcarriers relative to gelatin control beads. More specifically, dynamically-cultured hASCs on DAT-based microcarriers demonstrated greater lipid loading, as well as higher glycerol-3-phosphate dehydrogenase (GPDH) activity, a key enzyme involved in triacylglycerol biosynthesis, at 7 days and 14 days in culture in an inductive medium. Overall, the results indicated that the DAT-based microcarriers provided a uniquely supportive environment for adipogenesis. Established microcarrier sterility and injectability further support the broad potential of these tissue-specific microcarriers as a novel, adipogenic, clinically-translatable strategy for soft tissue engineering. / Thesis (Master, Chemical Engineering) -- Queen's University, 2010-12-01 14:28:14.628

One of the most important factors for a successful performance of a load-bearing implant for hard tissue replacement is its mechanical compatibility with human bone. That implies that the stiffness should be close to that of a bone and the strength of the implant material must be high enough to bear the load applied under physiological conditions. The Young´s modulus of most of the commonly used biomedical alloys is larger than that of a human bone (around 100 GPa for cp Ti, 112 GPa for Ti-6Al-4V versus 10-30 GPa for cortical human bone). A stiffness reduction of Ti alloys can be achieved by two approaches: (i) selecting an alloy composition with low Young´s modulus i.e. a ß-type alloy and (ii) introducing a reasonable amount of porosity. The composition of Ti-40Nb was chosen for the present work, as it allows to stabilize a single ß-type phase with low Young´s modulus at room temperature. The samples were produced by a powder metallurgical approach. The Ti-40Nb alloy powder was obtained by ball-milling of elemental Ti and Nb powders. The influence of the milling parameters on the oxygen content in the milled powder was studied. Powders with a lowest oxygen content of 0.4 wt.-% had an almost single ß-type phase after heat treatment and quenching. Porous samples were produced by loose powder sintering, hot-pressing and sintering with NaCl as a space-holder. The influence of the different processing routes and different porosities on the mechanical properties of the alloy was studied. The samples produced by loose powder sintering had mechanical properties close to those of cortical human bone (Young´s modulus 20 GPa, compression strength 150 MPa) and the samples produced by loose sintering with space-holder materials had mechanical properties close to those of human spongy bone (Young´s modulus 0.2-2 GPa, compression strength 50 MPa). Porous Ti-40Nb samples were coated with bone-like hydroxyapatite by an electrochemical deposition method in order to improve the osseointegration of the samples with bone tissue. The experiments were carried out with samples produced by different routes and a correlation between the deposition parameters and the morphology of the hydroxyapatite needles was found.

Biodegradable, edible wheat gluten films offer a renewable alternative to plastic food packaging or can be incorporated directly in the food product. Wheat gluten is a good option because it forms a fibrous network, lending strength and elasticity to films. The goal of this research project was to produce, with a water-based film formulation and methodology, smooth, homogeneous wheat gluten films with low water vapour permeability (WVP). The water-based film formulation also served to compare the FT Wonder wheat cultivar, grown in Ontario, to commercially produced wheat gluten and determine the effect of wheat source on the film properties, surface morphology, surface hydrophobicity, WVP, and film swelling in water for different pH, temperature and casting surface conditions. Fluorescence, SPR, and casting formulation viscosity provided preliminary information on the mechanism of film formation and on gluten protein structure induced by modifying the film formulation. This research provides an alternate use for some Ontario wheat cultivars based on their properties in films compared to commercial sources of gluten. As a result, using Ontario cultivars to prepare gluten film packaging material has potential as an alternate source of income for Ontario farmers. This research also defines the film properties for gluten films produced from aqueous solutions, helping to identify processing parameters that could bring gluten films on par with plastic packaging and make gluten films a viable alternative food packaging material. Finally, it was determined that the water vapour permeability of wheat gluten films was not correlated to film surface contact angle.

This dissertation aims to further the understanding of the complex communication that occurs as cells interact with topographical and chemical patterns on a biomaterial interface. The research accomplishes this through two aims fabricating cell substrate surface topography and chemical patterns independently using non-cleanroom approaches, and analyzing higher order cellular response to surface features. The work will impact biomaterial surface modification and fabrication which will apply to biomedical implanted devices, tissue engineering scaffolds, and biological analysis devices. The first aim seeks to apply non-traditional topographical and chemical patterning methods in order to create independent topographical and chemical patterns on cell culture substrates. Experiments use the resulting patterned substrates to quantify cellular alignment to surface topography and compare the relative influence of topographical and chemical patterns on cellular response. The combined patterning methods of imprint lithography and micro-contact printing result in a high-throughput technique applicable to a variety of materials and a range of feature sizes from nanoscale through microscale, thereby enabling future analysis of cell response to surface features. The second aim evaluates the impact of topographical and chemical features on cellular differentiation. Experiments use patterned topography overlaid with a characterized chemical model layer to evaluate the effects of topography on myoblast differentiation and alignment. Chemical patterns that independently control available cell spreading area and modulate cell-cell contact are used to investigate the impact of cell-cell contact on differentiation.