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DESCRIPTION (provided by applicant): This application addresses broad Challenge Area (13) Smart Biomaterials - Theranostics and Specific Challenge Topic 13-ES-101, Methods to Evaluate the Health and Safety of Nanomaterials. Carbon-based engineered nanomaterials, such as single-walled carbon nanotubes (SWCNTs), have received notable attention due to their superior electronic, optical, mechanical, chemical, or even biological properties. Nanosized particles have a potentially high efficiency for deposition in both the upper and lower regions of the respiratory tract, are retained in the lungs for a long period of time, and induce more oxidative stress and cause greater inflammatory effects than their fine-sized equivalents, all of which suggest a need to better understand the impact of these particles on the body. Carbon nanotubes are projected to be incorporated into manufactured goods worth trillions of dollars in the next 5 years. Limited studies have reported toxicity and fibrosis following exposure to SWCNTs, which strongly suggests an urgent need to more fully understand the circumstances in which these materials might be compatible in or toxic to biological systems. The goal of our research plan is to elucidate the role that different particle characteristics and exposure/dose metrics (e.g., particle mass, surface area and size) of inhaled SWCNTs have on biological fate and toxicity. We hypothesize that inhaled SWCNTs cause localized cell injury and alter the biochemical homeostasis of the respiratory tract through oxidative stress that is mediated by direct particle interactions and release of pro-inflammatory mediators. It is further postulated that these effects are driven in large measure by molecular interactions of particle characteristics, chemistry, and morphology (i.e., metal contaminants, surface imperfections, dangling bonds, surface area, reactive functional groups, and size) with vital cellular structures. Our research plan will implement a number of novel approaches for material synthesis and aerosolization, as well as visualization of SWCNT-cell interactions at a regional, cellular and molecular level in the lungs. The aim of this research plan is to test the following specific hypotheses: (1) Inhalation of SWCNTs causes cellular injury, oxidative stress, and changes in biochemical homeostasis in the respiratory system of exposed animals; (2) SWCNT particle retention patterns and impaired macrophage function are associated with regional patterns of cytotoxicity and cellular remodeling; (3) Particle physicochemistry, specifically iron content, structural defects, and morphology, influences the extent of cellular injury and oxidative stress in the lungs of animals exposed to airborne carbon-based nanoparticles; and (4) Compromised lipid membrane integrity, diminished antioxidant capacity, and induced lipid peroxidation contribute to the regional cytotoxicity within the lungs caused by inhaled SWCNTs. This experimental design will bring together a number of novel approaches to address key issues regarding the potential health effects of inhaled engineered nanomaterials. This research program will provide unique and new information in offering a more complete understanding of the potential human health risks posed by these materials in industrial, consumer use, and environmental settings, as well as the physical and chemical characteristics of selected engineered nanomaterials that may drive the potential hazards. Our work will provide a more broadly applied understanding of how inhaled ultrafine or nanosized particles produce effects through physical or chemical particle-cellular interactions in the respiratory system and possibly other target organs. We envision that our approach can be broadly used through physical-chemical-activity patterns to determine the mechanisms of toxicity of other engineered nanomaterials and will aid in setting future occupational and environmental standards based on data reflective of the most sensitive health outcomes and relevant routes of exposure. Achieving a better understanding of the dynamics at play between particle physicochemistry, transport patterns, and cellular responses in the lungs and other organs will provide a future basis for establishing predictive measures of toxicity or biocompatibility and a framework for assessing potential human health risks.
PUBLIC HEALTH RELEVANCE: Our work will provide a broad understanding of how inhaled ultrafine or nanosized particles in the form of single-walled carbon nanotubes (SWCNTs) produce effects through physical or chemical particle-cell interactions in the respiratory system and possibly other target organs. We envision that our approach with SWCNTs can be widely used to define physical-chemical-activity pathways that will aid in setting future occupational and environmental standards based on data reflective of the most sensitive health outcomes and relevant routes of exposure.
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