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Brianna Jepsen, Elizabeth Melssen, and Megan Knobeloch Receive NSF Graduate Research Fellowship Program Awards

July 31, 2023

Congratulations to graduate students Brianna Jepsen (Li Group), Elizabeth Melssen (Raff Group), and Megan Knobeloch (Skrabalak Group) on their recent National Science Foundation (NSF) Graduate Research Fellowship Program (GRFP) Awards.  Jepsen is the recipient of a Graduate Research Fellowship and both Melssen and Knobeloch received honorable mentions. The purpose of the NSF GRFP is to ensure the quality, vitality, and diversity of the scientific and engineering workforce of the United States. GRFP seeks to broaden participation in science and engineering of underrepresented groups, including women, minorities, persons with disabilities, and veterans. The five-year fellowship provides three years of financial support inclusive of an annual stipend of $37,000.   

Brianna Jepsen’s (Left) research focuses on the design and synthesis of atomically precise, water-soluble graphene quantum dots for applications in photodynamic therapy. Graphene quantum dots have size-dependent optical and electronic properties due to quantum confinement and are currently being explored for applications in photodynamic therapy. Photodynamic therapy is a non-invasive cancer therapy that involves light irradiation of a photosensitizer which can undergo energy transfer to excite molecular oxygen to a reactive, singlet state that in turn kills nearby cells through oxidative stress. The side effects of the treatment can be limited by localizing the treatment to the tumor site, using long wavelength light for irradiation, and high efficacy and low toxicity of the photosensitizer. Longer wavelengths also penetrate deeper into skin and mucous tissue, expanding the applications of the treatment. Graphene quantum dots can be used as photosensitizers in photodynamic therapy because of their large, conjugated core that allows for absorption of long, near-infrared light. With this project, Brianna hopes to expand on the current understanding of graphene quantum dots as photosensitizers and explore the potential of them to be used in photodynamic therapy. In addition, her fellowship will allow for more time to pursue collaborations and learn additional techniques to advance her project. This will also allow more time to engage with students and build scientific inquiry amongst them through outreach at a local high school and the design of a WonderLab exhibit.  

Elizabeth Melssen (Middle) studies photochemistry on soil surfaces and determines its impact on air quality and climate. Specifically, Melssen uses flow reactors and spectroscopic techniques to study how soil components such as transition metals and organic matter influence the mechanism by which nitrate is photodegraded under sunlit conditions.  Nitrate, which is a ubiquitous pollutant in soil, photolyzes to form nitrous acid (HONO) and NOx (NOx = NO and NO2), which are air pollutants responsible for photochemical smog.  To explore this complex soil chemistry, Melssen creates well-defined model soil systems containing nitrate where she systematically varies the chemical composition of the surface and variables such as pH and relative humidity to parse the mechanisms responsible for making nitrate a more effective atmospheric source of HONO and NOx than expected. With this work, she hopes to improve the accuracy of chemical transport models that are used to study air pollution and guide pollution control policy.
Megan Knobeloch’s (Right) research within the Skrabalak group focuses on the interrogation and regioselective modification of metal nanocrystals. Metal nanocrystals, defined as crystalline metal particles having at least one dimension less than 100 nanometers, are continually proving to be important components in fields such as catalysis, chemical sensing, electronics, and biomedical imaging. Their utility in these fields can be attributed to their large surface-area-to-volume ratios as well as the ability to tune their properties, which are accessed by modifying features such as their size, shape, composition, and architecture. As a result of their highly interdependent structure-property relationships, research is being conducted to better establish these relationships as well as to design new structures that may lead to enhanced or new properties. Part of Knobeloch’s research is conducted within the NSF-funded Center for Single-Entity Nanochemistry and Nanocrystal Design (CSENND), which strives to establish these relationships through both high-throughput and high-resolution single-particle characterization. The other part of Knobeloch’s research includes designing new structures through regioselective modification of metal nanocrystals and investigating the resulting optical properties to establish previously unknown structure-property correlations.

Since 1952, NSF has funded over 60,000 Graduate Research Fellowships out of more than 500,000 applicants.  Currently, 42 Fellows have gone on to become Nobel laureates, and more than 450 have become members of the National Academy of Sciences.  In addition, the Graduate Research Fellowship Program has a high rate of doctorate degree completion, with more than 70 percent of students completing their doctorates within 11 years.