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Fort Belvoir, Va. The development of novel catalysts and catalytic processes for Department of Defense chemical and biological defense applications is challenging. This challenge is largely due to a lack of detailed structure-function relationships necessary to drive the development of predictive capabilities toward new catalytic material design and catalyst process concepts capable of meeting current and future DoD and Chemical and Biological Defense Program (CBDP) needs. As such, warfighters may be inadequately protected against chemical and biological threats.
To enable stronger warfighter protection and accelerate progress in this field, Dr. Brian Pate from the Defense Threat Reduction Agency’s Joint Science and Technology Office is leveraging existing interagency programs focused on combining computational and phenomenological interface theory and experimental data.
Dr. Pate is fostering strategic coordination of DoD catalysis research and development efforts by leading a basic research assessment and interagency working group with representatives from the military services, the Army Research Office, Air Force Office of Scientific Research and Office of Naval Research.
Historically, new catalyst development was driven primarily by the United States chemical and petrochemical industries where catalysis is considered a core technology. Well-known and continued progress is made in several catalytic applications including the production of hydrocarbon or low-sulfur diesel fuels, the synthesis of vehicle lubricants, low temperature electrocatalytic polymer electrolyte fuel cells for mobile applications, catalysis of high-temperature solid oxide fuels for heavy auxiliary vehicle power applications, and developing nanostructured materials for various catalytic applications.
Emerging technologies in catalysis like the development of biocatalysts or the synthesis of catalytic antibodies now have the potential to provide novel DoD and CBDP-relevant capabilities enabling greater protection for the warfighter.
Molecular structure and design applications are frequently being targeted toward engineering new bio-functional and bio-inspired materials. Therefore, a deeper understanding of the underlying molecular physics is required to control the nanoscale structure and properties of these complex biological systems and applications.
Current catalysis efforts within the JSTO basic research portfolio focus on designing interfaces for both traditional (non-biological) and biological system applications, with a particular focus on coordinated reactivity and molecular transport phenomena.
This overall program infrastructure is an integrated cross-disciplinary effort that leverages existing, emerging, and new structural tools; computational modeling and simulation techniques; experimental and theoretical reaction pathway modeling; and data fusion techniques that merge the output from these disparate sources into coherent, predictive descriptions for catalyst structure and activity relationships for technologies that meet CBDP needs.
For example, the program recently completed two studies of the activity and stability of enzymes encapsulated into water-stable zirconium metal-organic frameworks (MOFs). These MOFs feature a hierarchical mesoporous channel structure and exhibit a record-high loading capacity of the enzymes. Notably, for the first time, a nerve-agent detoxifying enzyme was successfully encapsulated and showed significantly enhanced thermal and long-term stabilities after immobilization.
This work is a result of collaborative partnerships with academia and CBDP laboratories coordinated by JSTO’s Dr. Pate. In addition, this research successfully demonstrated that nanoparticles of water-stable zirconium MOFs can be successfully modified with a broad range of strut and node modifiers using orthogonal functionalization strategies, in order to induce exceptional stability against capillary forces together with excellent biocompatibility.
Additional program activities are focused on developing experimentally validated predictive understanding of multicatalyst composite films for capture and detoxification of chemical warfare agents and toxic industrial chemicals as shown below. These novel semipermeable barrier materials comprise a polyelectrolyte loaded with two types of catalysts, metal oxide nanoparticles and polyoxometalate nanoclusters, which promote hydrolysis and oxidation of common toxic agents.
The reactivity of developed nanocatalysts is being tested by the U.S. Army Research, Development and Engineering Command laboratory system.
In addition, two U.S. companies, which produce and distribute perfluorinated and block copolymer Proton Exchange Membranes, have expressed interest in potential licensing of the filed patents. Dr. Pate recently worked with these performers and dermal scientists in the program to explore applications in skin decontamination. Dr. Pate also coordinated with CBDP laboratory investigators focused on applications as multifunctional protective materials.
Additional efforts within the program include researchers who are working with enzyme pumps to achieve a fundamental understanding of the pumping mechanisms. This will assist in developing novel platforms that combine sensing and microfluidic pumping into single self-powered microdevices. The microdevices are powered by energy released from chemical reactions when a nerve agent is detected.
Using a combination of theory and experiments, the team has clarified the mechanism of the prototypical urease-based pump. They found that even simple enzymatic reactions can drive complex, time-dependent flows whose direction and speed depend critically on the relative diffusivities and expansion coefficients of the reactants and products. This approach allows for accurate prediction of the behavior of new pump designs under different conditions.
These engineered enzyme pump arrays have unidirectional fluid flows that can carry micron-sized particles towards a specific region in space, such as a detection area. Through Dr. Pate’s facilitation, the team has collaborated with CBDP laboratories to fabricate a pump with a mutant strain of a nerve agent hydrolyzing biocatalyst. Further, the team demonstrated that this pump will actively pull in and hydrolyze the nerve agent soman.
Finally, a research team within the program is engineering substrate enzyme-DNA nanostructures, designing reaction cascades for the multi-step destruction of the nerve agent VX. The research team is also engineering reactive degradation products and developing a novel materials strategy for the controlled assembly of multienzyme structures.
These efforts afforded a better understanding of the toxicity of VX hydrolysis products, specifically ethyl methylphosphonic acid (EMPA). The team identified EMPA as a potentially hazardous product because its reaction with VX produces the highly toxic compound diethyl dimethylpyrophosphonate. They also identified an enzymatic cascade that can attack both VX and EMPA. As this work matures, the outcomes lead toward a novel strategy of creating multienzyme systems that can be used to assemble enzyme cascades active towards the multi-step degradation of VX and EMPA.
In this era of rapidly advancing scientific and technological developments, these and other ongoing DoD catalysis efforts will enable future defense based technologies to protect the warfighter via countermeasures in chemically and biologically compromised environments.
| Date Taken: | 06.30.2016 |
| Date Posted: | 07.07.2016 09:25 |
| Story ID: | 203273 |
| Location: | FORT BELVOIR, VIRGINIA, US |
| Web Views: | 323 |
| Downloads: | 0 |
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