Projects | Emerging Research: Sensing and Capture with Magnetic Nanocomposites

Sylvia Daunert


J. Zach Hilt (Project Leader)
Tom Dziubla

PROJECT DESCRIPTION

Despite a production ban in 1979 and decades of remediation efforts, polychlorinated biphenyls (PCBs) remain a persistent environmental contaminant. Their ubiquity in the environment is further compounded by the extent to which they pervade multiple human exposure routes, e.g., soil, riverbeds, groundwater and milk. Gas chromatography mass spectrometry (GC-MS) remains the current standard for sensitivity and specificity in detecting PCBs in the environment. However, GC-MS requires intricate, time-consuming extraction and sample purification techniques. Alternatively, affinity-based methods typically require less processing and can even be coupled to remediation strategies for a single-step purification process, but current technologies also have limitations. For example, antibody-based affinity systems, which provide a very high level of specificity, are protein-based systems that characteristically have long-term stability problems, severely limiting their practical use as a field solution. Furthermore, they have proven expensive to produce. In addition, the poor aqueous solubility and low volatility of PCBs is problematic, and overcoming these challenges has limited previous technologies. Thus, complete remediation has been technically unattainable and economically impractical. Further, efforts to develop novel remediation strategies are complicated by the widely varying toxicity profiles of the many PCB congeners and similar compounds (e.g., Dioxin, bisphenol-A). Rapid identification and removal of specific species are critically important in assessing and mitigating potential risk associated with various exposure routes (e.g., riverbeds, groundwater, milk). In light of decreasing federal resources, there remains a need for a stable system that selectively binds and captures PCBs for sensing and remediation technologies.
It has been reported that the binding domains of PCB-specific antibodies (e.g., S2B1) form sterically constrained, highly aromatic (e.g., tryptophan, tyrosine) pockets, allowing for pi-pi bond stacking interactions. These same environments can also be seen in tests of PCB soil distribution (e.g., humin containing matter) and biodistribution (e.g., lipid rafts, PCB-binding proteins). We hypothesize that synthetic, biomimetic PCB binding domains can be synthesized by incorporating phenolic and related moieties into polymeric coatings, which will greatly enhance the ability to detect and remove/remediate PCB contamination. Polyphenols (e.g., plant derived flavonoids) and related chemistries offer an intriguing precursor for creating biomimetic affinity domains. Recently, we developed a novel strategy to synthesize polymeric networks that incorporate phenolic moieties, and in preliminary studies, we showed that PCB binding was increased through the incorporation of phenolic moieties in our polymeric coatings.

The overall goal of this project is to develop a magnetic nanocomposite platform that allows for the selective capture of PCB congeners with a range of affinities and selectivities. The specific aims are illustrated in the following schematic:

 

Schematic illustrating the inter-relationships between the aims.

The coatings are being engineered to have precise nanoscale thickness, tunable affinity/selectivity and reversible binding using surface initiated polymerizations, incorporating phenolic moieties and applying molecular imprinting approaches. Furthermore, some systems include environmentally responsive polymer components. The unique chemistries and methodologies will result in a nanomaterial platform that will provide new solutions for the capture, sensing, and remediation of PCBs, as illustrated in the schematic below:

Overall illustration of the novel composite magnetic nanoparticle platform
and the innovative application of these systems in the capture and sensing of PCBs.

PROJECT POSTERS AND PRESENTATIONS

See Endothelial Cell Dysfunction Project here

UK Superfund Research Student Angela M. Gutierrez

Research conducted by Angela M. Gutierrez, a first-year Ph.D. student under J. Zach Hilt and Tom Dziubla is focusing on the development of magnetic nanocomposite microparticles (MNMs) for on/off binding of persistent organic pollutants. MNMs are being produced using iron oxide nanoparticles incorporated into a polyphenolic-based polymer matrix with high affinity for organic pollutants. This platform allows for the specific binding of chlorinated organics, the rapid magnetic separation of bound organics from contaminated water sources, and the thermal destabilization of the polymer matrix for contaminant release and material regeneration. Pollutant binding studies are being performed using model chlorinated organic pollutants, polychlorinated biphenyls (PCBs, specifically PCB 126), to determine binding affinity and capacity, as well as optimal binding kinetics, and this is being quantified using LC-MS/MS. In preliminary studies, it has been demonstrated that the MNMs effectively bind PCBs with the addition of QMA resulting in greater affinity.
Her next step: further developing the nanocomposite materials and determining their stability and reusability.


UK Superfund Research Student Brad Newsome

Fifth-year graduate student Brad Newsome is developing composite nanomaterials for sensing and capture of PCBs, toxic compounds at Superfund sites in Kentucky and around the world. Polychlorinated biphenyls (PCBs) -- a class of hazardous chemicals used in coatings for electronics, sealants, adhesives, paint, and flame retardants -- were banned in the 1970s, but these toxic compounds continue to linger in groundwater and soil.

Newsome’s research focuses on creating a nontoxic way to address pollution by incorporating membrane filtration and magnetic separation with natural antioxidant polymers that bind organic pollutants. He is taking this research to Southeast Asia, through the Fulbright program, where he will develop water remediation techniques to deal with the rapid production of environmental pollutants in Cambodia.
Kentucky has more than 200 hazardous waste sites on the active list for control, cleanup or monitoring under the federal Superfund program. One such site is the Paducah Gaseous Diffusion Plant, the only operating uranium-enrichment plant in the United States and one of the top 14 sites on the EPA's national priority list.

UK Superfund Student Brad Newsome from Reveal on Vimeo

PROJECT STUDENT & POSTDOCTORAL RESEARCHERS

Angela Gutierrez

Brad Newsome

 

 

THE SENSING AND CAPTURE WITH MAGNETIC NANOCOMPOSITES PROJECT RESEARCH TEAM

 
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