Saudi Cultural Missions Theses & Dissertations
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Item Restricted Sustainable Food-based Nanotechnology for Sensing Applications(University of Sussex, 2024-01-19) Aljarid, Adel; Boland, ConorRecent advancements in hydrogel nanocomposites have shown that they have the potential to be highly sensitive electromechanical sensors, surpassing the capabilities of traditional materials. One way to improve their conductivity is by incorporating a network of graphene into the composite, which affects the arrangement and structure of the graphene sheets. When the hydrogel is mechanically strained, the conductivity of the material changes accordingly, making it an ideal choice for sensitive applications. The objective of this research is to expand the investigation on sustainable nanocomposites by utilizing biodegradable polymers derived from algae These materials exhibit intriguing physical characteristics, such as transforming into hydrogels with soft mechanical properties when immersed in a food-grade calcium chloride solution. Interestingly, the mechanical properties of these hydrogels remain consistent regardless of the amount of filler added. However, the electrical conductivity of the hydrogel does increase with more filler. Furthermore, these hydrogels have the most significant piezoresistive response of any hydrogel recorded in literature, making them ideal for pressure sensing applications. They are also soft, which is another desirable quality for these applications. For impact sensing, the hydrogels display the lowest response on set impact energies on record, and their response time remains consistent. Overall, these results suggest that hydrogel nanocomposites made from biodegradable polymers could be a promising material for various applications. However, there are still some challenges that must be overcome during the development and testing of hydrogel polymers. One issue is determining the optimal level of swelling and water absorption that will not affect their mechanical properties. Additionally, hydrogels lack the ability to self-heal after undergoing testing, and they tend to dry out quickly. Factors such as size, dimensions, water content, and temperature can influence the drying process. On a different note, these characteristics make hydrogel polymers perfect for single-use or continuous wear for up to 8 hours. Thanks to their quick and cost-effective production, they are well-suited for single-patient use. After use, they can be disposed of without the need for sterilization, eliminating the risk of potential cross-infection that can occur with traditional sensors commonly found in hospitals.4 0Item Restricted Novel Bioactive Low-Shrinkage-Stress Composite with Antibacterial and Remineralization Properties(Saudi Digital Library, 2023-11-28) Alhussein, Abdullah; Huakun, Xu; Michael, D. Weir; Abraham, Schneider; MaryAnn, Jabra-Rizk; Jirun, SunMethacrylate-based resin composites are frequently employed in dentistry for their aesthetic qualities, durability, and adhesive properties. Nevertheless, these restorations generally exhibit a lifespan of 5 to 10 years, with recurrent caries and tooth fractures being primary failure factors. Marginal integrity and the absence of bioactivity at the tooth-restoration junction contribute to recurrent caries development. Consequently, this dissertation endeavors to introduce a novel bioactive low-shrinkage-stress nanocomposite, featuring dimethylaminododecyl methacrylate (DMADDM) as an antibacterial agent, as well as remineralization nanoparticles of calcium fluoride (nCaF2) and nanoparticles of amorphous calcium phosphate (NACP), with the potential of increase the longevity of dental restoration and protect tooth structure. All novel formulations of low-shrinkage-stress composite were subjected to a series of mechanical, antibacterial, cytocompatibility, and ion release assessments. First, we investigated the optimum concentration of DMADDM that can be incorporated with a low-shrinkage-stress composite without compromising mechanical properties. We found that incorporation of up to 5% DMADDM into a low-shrinkage stress composite efficiently inhibited Streptococcus mutans (S. mutans) biofilm commonly associated with secondary caries. This potent antibacterial effect is achieved while maintaining excellent mechanical properties and minimizing polymerization shrinkage stress, potentially improving the long-term success of dental restorations. Next, we investigated the antibacterial and cytocompatibility of the incorporation of 3% DMADDM with 20% nCaF2 or 20% NCAP into a low-shrinkage-stress nanocomposite. We found that incorporating DMADDM with either nCaF2 or NACP into a low-shrinkage-stress nanocomposite provides a potent antibacterial effect against S. mutans biofilm while maintaining excellent mechanical properties. In addition, the novel formulations demonstrated excellent biocompatibility against human gingival fibroblasts and dental pulp stem cells. Lastly, we investigated the ions release and antibacterial properties against a salivary biofilm for our innovative formulations. The innovative mixture of DMADDM, NACP, and nCaF2 demonstrated strong antibiofilm effects on salivary biofilm, while concomitantly releasing a significant amount of remineralizing ions. This nanocomposite is a promising dental material with antibiofilm and remineralization capacities, with the potential to reduce polymerization-related microleakage and recurrent caries.23 0Item Restricted Minimally Invasive Dentistry via Dual-Function Novel Bioactive Low-Shrinkage-Stress Flowable Nanocomposite.(2023) Albeshir, Ebtehal; Xu, HuakunThe application of biomaterials science is unique in dentistry because of the complexity of the oral cavity. The oral environment is considered the most challenging for material in the body in which high mechanical loading, bacteria, changing pH, and a warm, fluid environment. Understanding the physical, chemical, biological, and biocompatibility of restorative material is very important when choosing materials for specific dental applications and designing the best solution to replace tissue lost to disease or trauma. Resin-based composite has been introduced into conservative dentistry to minimize acrylic resins' drawbacks and silicate cements and amalgam restorations. It is the material of choice in dailydental practice for several reasons, including their good mechanical properties, conservative cavity design, and superior esthetics. However, the longevity of current resin composite restorations ranges only 5-10 years. Gap formation, recurrent caries and tooth fracture are the most common types of failure of clinical service. These failures are often caused directly or indirectly by the polymerization shrinkage stress of the dental composite materials. Thus, there is an increased need to develop a new generation of bioactive dental composite with the ability to reduce polymerization shrinkage stress, long-term antibacterial, remineralization abilities, and excellent mechanical properties. Therefore, this dissertation aims to develop a new bioactive low-shrinkage- stress dental composite containing dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP) and nanoparticles of calcium fluoride (nCaF2) which could be a promising approach to increase the chances of success of composite restorations and strengthen tooth structures. First, we formulated optimum percentage of bioactive low-shrinkage-stress resin composite with proper concentration of long lasting copolymerized antibacterial DMAHDM, and adequate percentage of remineralization nanoparticles. Second, we performed several investigations to test the novel formulations. The physical, mechanical, and biological experiments were studied. We found that the new bioactive low-shrinkage-stress resin composite significantly reduced the bacterial counts and metabolic activites, without compromising their mechanical properties in comparing to the commercial control and experimental control composites. The novel formulation of “45% UV+5% DMAHDM+20% NACP+30% glass” and “47% UV+3% DMAHDM+20% nCaF2+30% glass” potent triple benefits of antibacterial, remineralization, and lower shrinkage stress. They have a great potential to inhibit recurrent caries and increase restoration longevity.36 0