| NSF Org: |
CHE Division Of Chemistry |
| Recipient: |
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| Initial Amendment Date: | June 8, 2018 |
| Latest Amendment Date: | June 22, 2023 |
| Award Number: | 1808623 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Catherine Costello
cecostel@nsf.gov (703)292-2945 CHE Division Of Chemistry MPS Directorate for Mathematical and Physical Sciences |
| Start Date: | July 1, 2018 |
| End Date: | June 30, 2024 (Estimated) |
| Total Intended Award Amount: | $301,381.00 |
| Total Awarded Amount to Date: | $301,381.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
3009 BROADWAY NEW YORK NY US 10027-6909 (212)854-2708 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
3009 Broadway New York NY US 10027-6598 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Chemical Measurement & Imaging |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.049 |
ABSTRACT
With support from the Chemical Measurement and Imaging program in the Division of Chemistry, Professor Marisa Buzzeo of Barnard College and her team of undergraduate research students study how biological molecules communicate via the transfer of electrons. The tunable chemical reactivity that is accessible by the transfer of electrons is harnessed by Nature in a wide range of important biochemical processes. Photosynthesis and cellular respiration, for example, rely on the exquisite sensitivity and selectivity with which electrons are transferred between molecules. The Buzzeo group is focusing on the chemical properties of the essential trace element selenium, a natural antioxidant, to gain a deeper understanding of its unique role in biological electron transfer events. Their studies provide fundamental information regarding the reactivity distinctly afforded by the presence of this element. Findings from their work also have the potential to result in selective sensing of selenium- and sulfur-containing molecules, including in clinical settings. This project provides multiple interdisciplinary research opportunities for students at Barnard College, a liberal arts undergraduate institution for women, and bolsters the participation of underrepresented groups in the physical sciences via community-based outreach activities involving high school students from disadvantaged backgrounds and individuals with disabilities. The aim is to expose both groups to chemical concepts, applications, and careers that would otherwise appear unattainable or inaccessible.
The accurate measurement of redox potentials is imperative for detailed understanding of how species participate in electron-transfer reactions. Electrochemical studies of chalcogen-containing molecules are hindered by unwanted oxidation and adsorption on electrode surfaces. New electrode materials have been identified that demonstrate great promise for the aqueous measurement of chalcogen-containing redox-active molecules. It has been shown that the intrinsic reactivity between selenium and gold yields a stable and reproducible electrode surface modification that makes accessible diffusional electron transfer of solution-based chalcogen analytes. The Buzzeo group is working to characterize selenium-modified electrodes by a combination of spectroscopic and electrochemical techniques. Specifically, they are measuring the electrochemical behavior of biological selenium and sulfur species on selenium-modified gold substrates to obtain fundamental thermodynamic parameters, and using the optimized selenium-modified surfaces to develop a portable electrochemical biosensor for cystine, a known culprit in kidney stone formation. Aided by collaborations across several departments and institutions, the work entails characterization of both surface and solution speciation to build a molecular-level description of the selenium-gold adsorbate layer. Sensing capabilities are assessed through comprehensive electroanalytical study of selenium- and sulfur-containing amino acids, peptides, and ligands. Together these pursuits will yield fundamental knowledge about selenium-gold surface reactivity and will enable measurement of physiologically relevant redox-active species. The work offers Barnard undergraduates research training at the interface of physical, inorganic, analytical, and biological chemistry. Additionally, the work includes educational activities involving high school students from disadvantaged backgrounds and individuals with disabilities to promote a more diversified STEM workforce.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
This project explored the use of selenium-modified gold substrates for electrochemical characterization of physiologically relevant redox-active species. Chalcogen-based molecules equip the cellular environment with essential chemistry. Sulfur- and selenium-containing amino acids and ligands participate in key redox reactions, yet several thermodynamic parameters of these processes remain unknown, largely due to practical experimental limitations. Aqueous electrochemical studies of chalcogen-containing molecules are hindered by unwanted oxidation and surface adsorption as sulfur and selenium species react readily with metallic electrodes to form self-assembled monolayers and films. Prior work had demonstrated that gold substrates modified by a selenium source via electrochemical cycling made organochalcogen voltammetry accessible. This award supported application of these selenium-modified gold electrodes to the fundamental electrochemical study of biological, chalcogen-containing molecules.
Layered construction of the selenium-modified gold substrates was optimized to allow for sequential electrochemical modification and spectroscopic surface characterization. Template-stripped gold surfaces were used to minimize aerial exposure prior to electrochemical measurement. Comparative voltammetric studies were conducted on a series of organochalcogen compounds, including selenocystine, cystine, cysteine, selenomethionine, and glutathione. Results on bare and modified electrodes indicate distinct surface interactions between selenium and gold relative to sulfur and gold. Reactivity between selenocystine and cysteine was examined by surface-controlled voltammetry and solution-based redox titrations. Analyses also extended to physiologically relevant ligands to assess antioxidant properties of selenium and sulfur. Ongoing work will continue to optimize conditions for quantitative voltammetric profiling of these reactive species and further develop customized electrochemical cells for the modified gold substrates. The fundamental studies supported through this award will contribute to our understanding of selenium’s redox role in the physiological environment.
The project provided research opportunities for thirteen undergraduate students at Barnard College. Students were trained at the interface of physical, inorganic, analytical, and biological chemistry and were engaged in experimental design and execution, chemical literature surveying, data analysis, and scientific writing and presentation. This work also afforded collaborative educational opportunities for individuals with and without disabilities through an ongoing partnership with a non-profit organization in Vermont.
Last Modified: 12/31/2024
Modified by: Marisa Buzzeo
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