Elizabeth Decoteau, Cahill Group & Naomi Ni, Hao Lab, Graduate Students, GW Department of Chemistry

Fri, 5 April, 2024 10:00am - 11:00am

Elizabeth Decoteau, Graduate Student, Cahill Lab
Elizabeth Decoteau, Graduate Student, Cahill Group, GW Department of Chemistry

Halogen- and Hydrogen-bonding Effects in a Series of Uranyl Fluorides and MOFs for  Radionuclide Detection

Spent nuclear fuel stewardship has been at the forefront of actinide chemistry since the advent of nuclear weapons and nuclear energy. Spent fuel is comprised of an evolving mixture of radioactive elements, many of which take hundreds to thousands of years to decay into stable isotopes. The disposal, safe handling, and detection of these materials calls for research to understand their reactivity and properties.
The uranyl cation, UO 2 2+ , is the most stable and environmentally relevant form of uranium featuring strong U=O bonds which impart significant stability. In the current project, we study uranyl fluoride materials which are some of the most prominent species of uranium in the nuclear fuel cycle. In a series of uranyl fluoride materials, structural analysis revealed molecular assembly via noncovalent interactions in the second coordination sphere with close halogen-oxo contacts. These interactions were probed via Raman spectroscopy where a decrease in the halogen-oxo distances manifests as a red-shifting trend among the Raman U=O symmetric stretches. This spectroscopic trend coupled with computational analysis supports the conclusion that more polarizable halogen atoms allow for stronger halogen-oxo interactions, thus weakening the U=O bond. Another aspect of nuclear fuel stewardship is the development of functional materials for capture and detection of relevant radionuclides in support of (for example) forensics applications. We sought to synthesize a metal organic framework (MOF) that could trap certain radioisotopes and provide an optical indication of their presence via scintillation. Presented herein is a series of isostructural MOFs, [Ln 2 (TFTA) 3 (2,2’-bpy) 2 (H 2 O) 2 ] (Ln = Sm-Er), consisting of lanthanide metal cations bound to tetrafluoroterephthalate linkers and 2,2’-bipyridine capping ligands. Crystal structures and void space calculations suggest these materials can uptake radioactive noble gas species, and efforts are in progress to ascertain scintillation properties.

 

BIO

Elizabeth received her B.S. in Chemistry from Bloomsburg University of Pennsylvania where she did undergraduate research under Dr. Matthew Polinski, studying nuclear and synthetic solid-state inorganic chemistry. Elizabeth then joined Professor Christopher L. Cahill’s research group in 2022 to pursue her Ph.D.in the field of nuclear chemistry. 

 

Naomi (Jiawei) Ni
Naomi Ni, Graduate Student, Hao Lab, GW Department of Chemistry

Developing a Mass Spectrometry-based Secreted Proteomics Workflow in Human Stem Cell-derived Neurons

Neurons secrete various proteins to transmit chemical signals between synapses and other target cells. Deep profiling of the neuron secretome can provide insights into neurobiology and the molecular pathways underlying brain diseases. Secreted proteins are often obtained from serum-free cell culture media to reduce contaminant protein interference, but this often sacrifices cell viability and health. We have developed a custom-made carrier-free neuron medium that minimizes contaminant protein interference while still containing low abundant growth factors that maximize neuron health. We systematically evaluated and optimized various neuron culture parameters, sample preparation methods, LC-MS acquisition methods, and data analysis workflows to enable a deep secretome analysis of neurons. Furthermore, we evaluated the neuron secretome under oxidative stress and compared the neuron secretome with other cell lines (e.g., stem cells, cancer cells) to understand the unique physiological features of neurons.

 

BIO

Naomi received her B.S. in Pharmaceutical Chemistry from UCSD and her M.S. in Chemistry/Biotechnology from Tufts University. In 2021, Naomi joined Dr. Hao’s research group at GW. Her research project has been focused on developing mass spectrometry-based analytical chemistry methods and proteomics strategies to understand neuron secretion.

Where
Science & Engineering Hall 800 22nd Street, NW, Room: B1220 Washington DC 20052
Room: Room: B1220; Meeting Number: 202-994-6121

Admission
Open to everyone.

Contacts
Chemistry Department
[email protected]
202-994-6121

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