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Dissertation/Thesis Abstract

Toxicity Evaluations of Nanoclays and an Associated Nanocomposite throughout Their Life Cycle
by Wagner, Alixandra, Ph.D., West Virginia University, 2018, 176; 10977044
Abstract (Summary)

Nanoclays are layered mineral silicates that originate from the clay fraction of soil and carry a platelet thickness of about 1 nm and lengths and widths of up to several microns. Due to their nanoscale dimensions, they have been used for numerous applications ranging from media for oil well drilling to sorbents in treatment of waste-water. Additionally, upon functionalization with organic modifiers, nanoclays have been incorporated into polymers to form nanocomposites with increased mechanical strength, barrier properties, UV dispersion, and fire resistance to be implemented in food packaging or medical devices related applications. Such increased implementation into industrial and commercial products has brought scrutiny onto nanoclays and associated nanocomposites toxicity. Previous studies have shown for instance that nanoclays induce cytotoxic and genotoxic effects upon cellular or model animal exposure, however little investigations were performed to identify how nanoclay functionalization may influence such toxicological profiles. Moreover, most of the studies related to nanoclays and nanocomposites toxicity only refer to their consumption/usage exposure and fail to assess manufacturing or disposal exposures.

Herein, we aimed to understand how the physical and chemical properties of nanoclay systems (i.e. pristine and organically modified, along with a nanoclay-enforced nanocomposite) in both their as-received (mimicking manufacturing) and thermally degraded (mimicking end of life cycle incineration) forms influence lung cells, used to model inhalation toxicity. Physical and chemical properties of the materials were investigated via microscopical and spectroscopical approaches, while toxicity profiles were assessed both in real-time or at disparate time points via in vitro cellular and molecular assays, cell imaging, and electric cell-substrate impedance sensing. Our analyses showed that nanoclays and nanocomposites properties (both physical and chemical) influence the materials’ degradation profile and ultimately their induced toxicity in model cellular systems. The toxic effects were displayed either by reductions in cell proliferation and viability, changes in cell morphology, and/or alterations in the cell cytoskeleton. Overall, our results provide unique insights into how materials properties, both physical and chemical dictate materials’ toxicological profiles throughout their life cycle (from manufacturing to disposal) with such information to be possibly aiding in safe-by-design strategies as well as safety protocols implementation in areas of exposure.

Indexing (document details)
Advisor: Dinu, Cerasela Zoica
Commitee: Gupta, Rakesh K., Sierros, Konstantinos A., Stinespring, Charter D., Stueckle, Todd A.
School: West Virginia University
Department: Engineering & Mineral Resources
School Location: United States -- West Virginia
Source: DAI-B 80/04(E), Dissertation Abstracts International
Subjects: Engineering, Chemical engineering
Keywords: Life cycle, Lung cell, Nanoclay, Nanocomposite, Toxicity
Publication Number: 10977044
ISBN: 978-0-438-72385-6
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