Surface Characterization of Ambient Ultrafine Particles
EMSL Project ID
10792
Abstract
The ultrafine fraction (<0.1 mm diameter) of ambient particulate matter (PM) caused by combustion has recently been shown to induce significant oxidative stress in macrophages and epithelial cells and to cause major damage to mitochondrial membranes (Li et al., 2003). Emerging nanotechnologies will cause additional emissions of previously unknown ultrafine particles (UFPs). The elucidation of the toxicological mechanisms by which UFP pollutants cause adverse health effects such as respiratory and cardiovascular dsyfunction is thus a major issue in present and future public health. Although much work has been done analyzing the total chemical composition of PM of various sizes from many parts of the world, it is clear that biological systems interact first with the surfaces of these particles. In recent years, the importance of the surface chemical composition of these particles has been recognized and surface analysis of collected PM is of much interest. So far, however, there are very few studies on the surface composition of the ultrafine fraction alone, despite the very large surface area they present to living tissue and the particular adverse health effects that this fraction may induce. At the present time, very little is known about the mechanisms underlying UFP toxicity and the possible role of metallic elements and/or organic species at their surfaces.The work proposed here is part of a collaboration between three faculty members at Central Washington University (CWU): Carin Thomas, a biochemist, Eric Bullock, a surface chemist, and Anne Johansen, an atmospheric chemist. UFPs will be collected from Seattle and Ellensburg, WA using existing instrumentation at CWU and tested for reactive oxygen species (ROS) generation and electron transport chain dysfunction in bovine heart mitochondria according to protocols already established at CWU. For this study, we propose to combine these biochemical assays with an analysis of the surface chemical composition of the collected UFPs. A combined analysis of collected fractions which show both unusually high and unusually low toxic reactions in these assays using time of flight secondary ion mass spectrometry (TOF-SIMS), x-ray photoelectron spectroscopy (XPS), and particle-induced x-ray emission (PIXE) for bulk analysis is proposed. The high mass resolution of TOF-SIMS should provide detailed information on the metallic and chemical species at the surfaces of the UFPs and XPS should allow a quantitative surface elemental analysis as well as information on iron and other metal speciation. PIXE analysis will provide a bulk analysis of the particle composition and a comparison with the surface analysis should provide information on surface chemical enrichment. By correlating the surface characterization of ambient UFPs with the production of (ROS) in mitochondria, we hope to determine which organic compounds or metallic elements occurring on the surface of UFPs are responsible for mitochondrial damage and oxidative stress. In particular, Fe(II) and polycyclic aromatic hydrocarbons, both of which have been observed on the surfaces of larger PM (Zhu et al., 2001) and both of which have implicated in oxidative stress mechanisms, will be targeted. In this way, we hope to make significant advances in our understanding of the toxicological mechanisms underlying the adverse health consequences of present and future UFPs.
N. Li, C. Sioutas, A. Cho, D. Schmitz, C. Misra, J. Sempf, M. Wang, T. Oberley, J. Froines, and A. Nel, Ultrafine Particulate Pollutants Induce Oxidative Stress and Mitochondrial Damage. Environ. Health Perspect. 11 455-460 (2003).
Y.-J. Zhu, N. Olson, and T.P. Beebe, Jr., Surface Chemical Characterization of 2.5 mm Particulates (PM2.5) from Air Pollution in Salt Lake City Using TOF-SIMS, XPS, and FTIR. Environ. Sci. Technol. 35 3113-3121 (2001).
Project Details
Project type
Exploratory Research
Start Date
2004-09-03
End Date
2006-10-04
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members