Joel Pedersen

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Room Number: 
103 H. Smith Annex (Soils)
Group Affiliation: 
Pedersen Group
Position Name: 

B.S., University of California, Irvine
M.S., California Institute of Technology
Dr.Env. Environmental Science and Engineering, University of California, Los Angeles

Also: William A. Rothermel Bascom Professor in Soil Science

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Research Description

The Pedersen research group focuses on environmental interfacial chemistry and studies interfacial processes affecting the behavior of nanoparticles, biomolecules, and organic molecules in terrestrial and aquatic environments. Current research topics include molecular-scale interactions of biomolecules with engineered nanoparticles, the processes governing the environmental transmission of prion diseases, and the interaction of polar and ionizable organic molecules with natural organic matter and mineral surfaces.

The Nano-Bio Interface

Sustainable development of nanotechnology requires molecular-level understanding of the interaction of nanomaterials with biological interfaces, both to design applications that interface with biological systems and to evaluate the potential risks posed by release of nanoscale materials into the environment. Developing such an understanding is a challenging problem because both nanoparticles and biological interfaces (e.g., cell surfaces, proteins) are structurally and chemically complex. Our group focuses on the interaction of nanoparticles with cell membranes and proteins. We are interested in determining how nanoparticle size, shape, and surface chemistry influence attachment to, penetration of, and disruption of cell membranes, and how the composition of membranes impacts their interaction with nanoparticles. Nanoparticles possess high surface energy. When nanoparticles are introduced into environmental or biological media their surfaces tend to acquire a coating, or corona, of molecules from solution to reduce surface energy. The nature of this environmental or biomolecular corona has important consequences for the biological impact of nanoparticles (whether beneficial or adverse) by affecting uptake by and distribution within organisms, interaction with membranes, and recognition by the immune system. Our group is interested in how nanomaterial properties influence the composition of environmental and biomolecular coronas and how such coronas affect interaction with cell surfaces. The interaction of proteins with nanoparticle surfaces may induce conformational changes that alter their function or expose portions of protein to solution that are normally buried within the protein’s structure, triggering unexpected biological responses. We are therefore interested in the conformational changes in proteins induced by association with nanoparticle surfaces. We employ a wide suite of techniques to address these problems. Our work is highly interdisciplinary, and students from all areas of chemistry and related fields are welcome.

Environmental Transmission of Prion Diseases

Prion diseases, or transmissible spongiform encephalopathies, are inevitably fatal neurodegenerative diseases and include Creutzfeldt-Jakob disease and kuru in humans, bovine spongiform encephalopathy (“mad cow” disease) in humans, scrapie in sheep and goats, and chronic wasting disease in deer, elk, and moose. Environmental routes of transmission contribute to the spread of chronic wasting disease and scrapie. The infectious agent in these diseases is a misfolded form of a host-encoded protein referred to as a prion. Prions are notoriously difficult to inactivate, being resistant to sterilization methods that are effective against conventional pathogens. We have provided insight into the environmental transmission of prion disease by demonstrating that association of prions with microparticles dramatically enhances oral disease transmission. We are currently investigating the mechanisms by which this occurs. We have developed exquisitely sensitive methods to detect prions in environmental matrices, allowing us to study their release into and movement within the environment. Methods to sterilize prion-contaminated surfaces are needed to limit the environmental transmission of these diseases and to decontaminate sensitive medical equipment. We are developing new methods to inactivate prions adsorbed to surfaces.

Environmental Chemistry of Polar and Ionizable Organic Contaminants

Pharmaceuticals and personal care product ingredients have emerged as widespread environmental contaminants. Many of these compounds are polar and ionizable organic molecules. The environmental behavior of such compounds is considerably less well understood than that of more widely studied nonpolar organic contaminants such as polychlorinated biphenyls, organochlorine insecticides, and polycyclic aromatic hydrocarbons. Our group is interested in uncovering the mechanisms by which multifunctional pharmaceutical compounds associate with natural colloids because such interaction influences the transformation and bioavailability of these inherently biologically active molecules. In water-stressed areas of the world, treated wastewater is used to irrigate food crops. Conventional wastewater treatment processes do not efficiently remove many pharmaceuticals and personal care product ingredients. Concern exists that irrigation with treated wastewater may lead to the accumulation of these compounds in the edible tissues of plants. Our group is investigating the mechanisms by which polar and ionizable organic compounds accumulate in plants.

Awards and Honors

Environmental Science & Technology Excellence in Review Award 2012
National Science Foundation CAREER Award 2006
ASA/CSSA/SSSA Early Career Professional Award 2006
U.S. Environmental Protection Agency Bronze Medal 2001
Charles F. Scott Fellow, UCLA 1998