Yibo Wang, a graduate student in the Gahlmann Group, has been awarded a 2020-2021 Dean's M.S.-Ph.D. Fellowship in Data Science.The fellowship will allow Yibo to complete an M.S. in Data Science en route to his Ph.D. in Chemistry. Congratulations Yibo!

Seminars

Sensing through the Skull: Developing Surface-Enhanced Spatially-Offset Raman Spectroscopy (SESORS) for in vivo Neurochemical Detection

Sensing through the Skull: Developing Surface-Enhanced Spatially-Offset Raman Spectroscopy (SESORS) for in vivo Neurochemical Detection

Dr. Bhavya Sharma | University of Tennessee, Knoxville

Hosted by Professor Jill Venton

Sensing through the Skull: Developing Surface-Enhanced Spatially-Offset Raman Spectroscopy (SESORS) for in vivo Neurochemical Detection

The brain is a complex organ, with billions of neurons and more than 30 distinct neurochemicals (possibly up to 100), involved in all aspects of a human life, including cognition, movement, sleep, appetite, and fear responses. For some neurological diseases/conditions, changes in neurochemical concentrations could be predictors of early onset disease or disease progression. While there are a variety of sampling techniques which can detect neurotransmitters in biofluids at low concentrations, these techniques often involve multi-step sample preparations coupled with long measurement times, and are not suited for in vivo detection. There is a need for the development of sensors for the detection of neurotransmitters that are selective, rapid, and label-free with little to no sample processing. We focus on the detection of biomarkers for neurological activity in biofluids and through the skull.

Our approach is to apply surface enhanced Raman spectroscopy (SERS), a highly specific and selective vibrational spectroscopy, for the detection of neurochemicals. Raman scattering is an inherently weak phenomenon. We incorporate the electric field generated at the surface of noble metal nanoparticles in our sensors to enhance the weak Raman scattering signal. SERS is surface selective, highly sensitive, rapid, label-free and requires little to no sample processing. We are developing SERS-based sensors for in vitro neurotransmitter sensing at physiologically relevant concentrations in biofluids. For in vivo detection, we combine SERS with spatially offset Raman spectroscopy (SORS), where Raman scattering spectra is obtained from subsurface layers of turbid media.  We demonstrate detection of physiologically relevant concentrations of neurotransmitters in the micromolar (µM) to nanomolar (nM) concentration ranges with SESORS in a brain tissue mimic through the skull.

Friday, October 23, 2020
Incorporating Metal-Ligand and Metal-Metal Cooperativity into First Row Transition Metal Complexes with Applications in Catalysis

Incorporating Metal-Ligand and Metal-Metal Cooperativity into First Row Transition Metal Complexes with Applications in Catalysis

Dr. Christine Thomas | Ohio State University

Hosted by Professor Charlie Machan

Incorporating Metal-Ligand and Metal-Metal Cooperativity into First Row Transition Metal Complexes with Applications in Catalysis

 

The formation and cleavage of chemical bonds in catalytic reactions relies on accessible two-electron redox processes that are often challenging for base metals such as first row and early transition metals. Metal-ligand and metal-metal cooperativity provide a potential solution to this challenge by enabling heterolytic bond cleavage processes and/or facilitating redox processes. Both strategies will be discussed, showcasing the many ways that metal-ligand and bimetallic cooperativity can operate and the methods by which cooperativity can be built into catalyst design. A tridentate pincer ligand featuring a reactive N-heterocyclic phosphido fragment is found to be both redox active and an active participant in bond activation across the metal-phosphide bond, with catalytic applications in alkene hydroboration. A tetradentate bis(amido)bis(phosphide) ligand has been coordinated to iron and it has been shown that the resulting complex can activate two σ bonds across the two iron-amide bonds in the molecule without requiring a change in the formal metal oxidation state. In the context of metal-metal cooperativity, phosphinoamide-linked early/late heterobimetallic frameworks have been shown to support metal-metal multiple bonds and facilitate redox processes across a broad range of metal-metal combinations and the resulting complexes have been shown to activate small molecules and catalyze organic transformations.

Wednesday, October 28, 2020
Inspiration from Fluorination:  Chemical Epigenetics Approaches to Probe Molecular Recognition Events in Transcription

Inspiration from Fluorination:  Chemical Epigenetics Approaches to Probe Molecular Recognition Events in Transcription

Dr. William Pomerantz | University of Minnesota

Hosted by Professor Marcos Pires

Inspiration from Fluorination:  Chemical Epigenetics Approaches to Probe Molecular Recognition Events in Transcription

 

Protein-protein interaction inhibitor discovery has proven difficult due to the large surface area and dynamic interfaces of proteins.  To facilitate the early lead discovery rate, I will first describe a rapid protein-based 19F NMR method for detecting protein-ligand interactions by screening low complexity molecules (fragments), drug-like molecules, and peptidomimetics. We have tested the sensitivity, accuracy, and speed of this method through screening libraries of small molecule fragments.  The advantages of using 3D-fragments for discovery of more selective hits for bromodomain-containing proteins will be specifically highlighted. In the second part of the talk, I will describe improvements in our method for the field of epigenetics targeting bromodomain and extra-terminal (BET) family proteins. These studies have led to a selective inhibitor for the first bromodomain of BRD4. Structure-based design has identified several new design rules for maintaining selectivity and potency.  Cellular efficacy in cancer and inflammatory model systems using this novel BRD4 inhibitor will be briefly described.  Finally, development of a new heterocyclic scaffold for the second bromodomain of BRD4 will be highlighted. The speed, ease of interpretation, and low concentration of protein needed for binding experiments affords a new method to discover and characterize both native and new ligands for bromodomains and may find utility in the study of additional epigenetic “reader” domains.

Friday, November 6, 2020

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