Biological Interactions of Nanomaterials
|Principal Investigator||Saber Hussain|
|Relevance to Implications||High|
|Class of Nanomaterial||Engineered Nanomaterials|
|Impact Sector||Human Health|
|Broad Research Categories||
|Anticipated Total Funding||$300,000.00|
|Anticipated End Year||2007|
Nanoscale science provides the basis for advancement in diverse areas such as medicine, energy, materials, agriculture, communications, and electronics. The cytotoxicity of nanomaterial, however, has yet to be thoroughly evaluated. Inadequate safety testing of man-made nanoparticles (NP) may produce unforeseen untoward consequences that may hinder technological progress, especially in the field of bio-nanotechnology. The overarching goal of this effort is to determine specific mechanisms activated by nanomaterials, which create bioeffects such as toxicity or change (loss/gain) in function within mammalian cells, and to evaluate how these mechanisms are elaborated and modulated by nanostructure including shape and charge as well as chemical composition, such as surface activity/reactivity, solid state maintenance, and rate and delivery molecular components after regional dissolution.
Objective: The objective the work effort is to characterize mechanisms which can translate into systems study and address the human health risks associated with exposure to nanomaterials that are of specific interest to Air Force, such as nanosize toxicity effect of aluminum and silver nanoparticles. The specific aims include: (1) Characterization of nanomaterials before, during and after biological interaction. These experiments are designed to understand the physicochemical nature of these particles and their impact on producing toxicity (2) Evaluate nanomaterial toxicity using in vitro cell models, such as phenotype under concern of exposure: macrophage, liver, PC12 cells, T-cell (Jurkat cell). These experiments will use several in vitro model systems to explore and evaluate the mechanisms of toxicity of NP of mammalian cell exposed to increasing levels of material with endpoint emphasis on signaling disruption (aberrant or diminished), loss of cell homeostasis systems, increased/decreased oxidative stress, apoptosis and immune response. Investigating nanotoxicity using multiple in vitro model systems will provide a comprehensive view on how man-made NPs interacts with a variety of processes including normal metabolism, respiration, immune responses, reproduction, and growth and development. (3) Analyze toxicogenomics of mammalian cells exposed to NPs. NPs differentially regulate gene expression in mammalian somatic cells and germline stem cells. In these experiments, we propose to use gene arrays to identify genes and pathways differentially regulated by NP using several different cell lines representing multiple tissue types (described in 2). Positive findings will be further pursued using proteomic and metabonomics investigations.
Approach: This project focuses on in vitro functional tests in various cell types (rat liver cells, alveolar rat macrophages, human Jurkat T cells, PC12 neuroendocrine cells, keratinocytes and germline stem cells) as representative of potential target organs that may be exposed depending on NP contact (e.g., ingestion, inhalation, dermal). Our proposed biochemical and genetic endpoints will provide a comprehensive view of how NPs are toxic to different cell types (phenotypes) and the molecular mechanisms involved. The assays proposed here represent vital biological functions and should provide a general sense of the impact of NP on cells. Using quantitative measures of cell viability, mitochondrial function and redox status, NP will be classified as to whether they are of high, intermediate or low toxicity when compared to a control. Generation of reactive oxygen species, reduced glutathione and mitochondrial membrane potential will be measured to determine if oxidative stress is the mechanism of toxicity. The degree of apoptosis, cell proliferation and DNA synthesis will be determined by standard techniques. Furthermore, we hope to gain insight into the mechanisms underlying the inflammatory/immune responses to NP.
Expected results/problems. Previous studies in our lab indicate that one mechanism by which NP are toxic to mammalian cells is in part through increased production of reactive oxygen species which results in oxidative stress, and eventually apoptosis. The physicochemical aspects of NP will likely to determine their interactions with cells with respect to their uptake, translocation, interference with cellular functions, and deposition within cellular substructures. The multiple cellular functional assays proposed here will present a comprehensive array of data which will allow us to identify how size, composition, and other characteristics of NP might affect cellular uptake and toxicity. The gene array data generated here will likely open new avenues for investigation in the area of NP toxicity. There are some challenges with standardization of NP exposure when conducting experiments at the cellular level. We will address the issue of exposure including homogeneous nanoparticle suspension and agglomeration, as well as NP turbidity in solution and their impact on toxicity assessment.