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Author: Kayla Benson

Sharma Lab Published in Analytical Chemistry and Analyst

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Terence MooreThe Sharma Raman Lab published their work “Direct Surface Enhanced Raman Spectroscopic Detection of Cortisol at Physiological Concentrations” in Analytical Chemistry.

Josh Moore is the first author on this piece and recently earned his PhD in the Chemistry program.

Cortisol is an important steroid hormone in vertebrate physiology and plays a role in acute and chronic stress response. Current methods for determination of cortisol concentrations in biofluids require extensive sample preparation and long run times. Raman spectroscopy is an attractive alternative because analysis is rapid and non-destructive to the sample.

The Sharma Lab has developed a surface-enhanced Raman spectroscopy (SERS)-based method for detection of cortisol in ethanol that shows a sigmoidal concentration response and a limit of detection of 177 nanomolar, which is in the physiologically relevant range. The method can be applied to more complex solvent environments through the use of multivariate analysis techniques, where principal components analysis (PCA) demonstrates a linear separation according to cortisol concentration in a serum mimic. “We are, to our knowledge, the first group to report on the detection of cortisol using label-free SERS, which does not require a Raman reporter molecule to obtain signal,” Moore said.

The Sharma Lab published their work “Surface-enhanced spatially-offset Raman spectroscopy (SESORS) for detection of neurochemicals through the skull at physiologically relevant concentrations” in Analyst. 

Detection techniques for neurotransmitters that are rapid, label-free, and non-invasive are needed to move towards earlier diagnosis of neurological disease. Surface-enhanced Raman spectroscopy (SERS) allows for sensitive and selective detection of target analytes. The combination of SERS with spatially offset Raman spectroscopy (SORS) in a technique termed surface enhanced spatially offset Raman spectroscopy (SESORS) permits a sensitive and selective detection of neurotransmitters through the skull.

In this piece, the group presents the SESORS detection of individual neurotransmitters and mixtures of neurotransmitters at physiologically relevant concentrations, while also establishing limits of detection.

Brantley Group Publishes in Polymer Chemistry

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The Brantley Group published their work “Ion Specific Fluorescence Modulation of Polyvinyl Alcohol-Boronate Matrices” in Polymer Chemistry. Brian Jacobs, graduate student in the Brantley Lab, is the primary author. 

Borylated polymers are emerging as valuable chemosensors that can report analyte binding through an array of responses. Fluorescent materials are particularly valuable in this regard, as modulation of their photophysical properties can facilitate rapid substrate detection and quantitation.

“In this manuscript, we report the condensation of aryl boronic acids onto polyvinyl alcohol (PVA) to afford fluorescent polymers, a phenomenon that has been widely overlooked,” Jacobs said. “ Importantly, selective modulation of the photophysical properties was observed in the presence of borophilic anions (e.g. fluoride, hydroxide, and cyanide).”

Density functional theory (DFT) calculations, performed by collaborator Jacob Townsend in the Vogiatzis Research Group, suggested that a combination of covalent and non-covalent interactions were crucial for anion binding. Time-dependent DFT computations were also performed to explain the appearance of a distinct peak in the polymer’s absorbace profile.

“Lastly, films of these PVA-aryl boronates were employed in ion extraction studies, highlighting a useful secondary function these materials possess,” Jacobs said. “Given the ease with which these polymers can be accessed, they could serve as general platforms for developing ion selective membranes or detectors.”

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Roy and Long Collaborative Work Published

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Catalysis Science & Technology published a collaborative piece from the Roy and Long groups titled  “A mechanistic study of microstructure modulation in olefin polymerizations using a redox-active Ni(ii) alpha-diimine catalyst.”

Polyolefins are among the world’s most widely produced and utilized classes of polymers, serving as synthetic alternatives to traditional materials such as wood, glass, and metal. While numerous prior research efforts have focused on the development of faster, more efficient, and less expensive catalysts, recent studies have demonstrated that redox-active olefin polymerization catalysts may also be employed to modulate catalytic activity, reactivity, and selectivity in situ.

The group reports a computational study based on density functional theory designed to better understand the structure and underlying olefin polymerization mechanisms of the active catalytic species in two distinct redox states. These findings are further supported through experimental evidence and suggest that upon activation of the reduced catalyst species, the added electron density of the catalyst is transferred from the active metal center to the alpha-diimine ligand.

The observed decrease in polyethylene branching that results from catalyst reduction is believed to stem from changes in the subtle balance of steric, electronic, and entropic effects, primarily perturbing the coordination of subsequent monomer units. This perturbation is expressed not only in the monomer-inserted-product energy differences but also in the catalysts’ deviation from square planarity about the Ni center. Through these studies, we can better understand how the addition of an electron to a Ni(ii) alpha-diimine catalyst perturbs its catalytic behavior, which may influence the design of future generations of redox-active olefin polymerization catalysts.

Awards Within the Vogiatzis Group

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The Vogiatzis Group’s research centers on the development of computational methods based on electronic structure theory and machine learning algorithms for describing chemical systems relevant to clean, green technologies. We are particularly interested in new methods for non-covalent interactions and bond-breaking reactions of small molecules with transition metals. Our overall objectives are to elucidate the fundamental physical principles underlying the magnetic, catalytic, and sorption properties of polynuclear systems, as well as to assist in the interpretation of experimental data.

Recent group awards:

    1. Mrs. Alexa Griffith, an undergraduate student pursuing research in my group, was awarded a DAAD exchange fellowship for pursuing research for three months at the Technical University of Kaiserslautern, Germany (2018).
    2. Mr. John Hymel, an undergraduate student pursuing research in the Vogiatzis Group, won the Award of Excellence in Natural Sciences and Office of Research and Engagement Bronze Award at the Exhibition of Undergraduate Research and Creative Achievement (EUReCA) (2018).
    3. Mr. Jacob Townsend, graduate student in the Vogiatzis Group, won the best Lightning Talk Award at PsiCon, the annual Psi4 software developers meeting (2018).
    4. Mr. Grier Jones, graduate student the Vogiatzis Group, received a travel grant from the Molecular Science Software Institute (MolSSI) to attend the MolSSI Workshop: The Open Molecular Science Cloud in Perugia and Rome, Italy (2019).
    5. Ms. Rebekah Duke, REU student who worked in the Vogiatzis Group during Summer 2019, was accepted to present her results that obtained at the University of Tennessee at the Posters on the Hill, an annual undergraduate poster session on Capitol Hill, Washington, DC (2020).

Kent & Zhao’s Most Read Article

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Shape Changing Brush Polymers Are Receiving Attention. 

Molecular bottlebrushes are complex polymers composed of polymeric side chains densely grafted on a relatively long backbone polymer. These types of polymers are found in our body and show important biological functions, e.g., joint lubrication by lubricin.

In an effort to develop smart polymers mimicking the function of the von Willebrand Factor, a protein important in the blood clotting cascade, Ethan W. Kent, a doctoral graduate student in Bin Zhao’s research laboratory, recently designed and synthesized dually responsive shape-changing star molecular bottlebrushes.

At acidic pH values and lower temperatures, the molecules take on a three-arm star shape with a span size of ~ 180 nm. When the pH is increased to basic or temperature is raised, the molecules undergo dramatic shape changes from stars to spheres with an average dimension of ~ 80 nm. 

“It is really cool to see these molecules change their shapes spontaneously,” Kent said. These brush polymers have potential in drug delivery, molecular actuators, and sensors. Ethan is currently applying his responsive brush polymers in sensors.

This work has been published in Macromolecules, an ACS journal in polymer science. The paper has been on the list of Most Read Articles in Macromolecules for nearly two months. “It is really exciting to see our paper garner a lot of attention” Kent said.        

BOV 2019

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The Department of Chemistry’s Board of Visitors (BOV) is a volunteer advisory body dedicated to helping the Department successfully fulfill its teaching, research and service missions and become one of the preeminent chemistry departments in the nation. The BOV has a vision of enriching the research and teaching endeavors and the intellectual capital of the Department.

This year’s annual meeting was held November 1-2, 2019. Activities included dinner downtown, faculty presentations, 10 year academic program review discussion, student poster session, invited speaker, Shea Kidd Houze, Homecoming Parade, banquet dinner at the Foundry, alumni tailgate, and attending the UAB football game.

Two graduate students were awarded for their posters presentations:

  • Jinchao Lou from the Best group titled”Calcium-triggered release of contents from liposomes for drug delivery applications”
  • Brandon Colon from the Calhoun group titled “Imaging excited-state dynamics of IR-144 with total internal reflection transient absorption microscopy (TIRTAM)”

View Poster Session Program 

The department recognizes and appreciates all of the support and interaction it receives from its engaged board.

Pictures from event

New Instrument in the PCL

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Small Angle X-Ray Scattering

The Xenocs Xeuss 3.0 SAXS instrument is a powerful technique that allows for the determination of size, distribution, shape, and order of nanoparticles and macromolecules. This instrument has 2 radiation sources, Cu and Mo, that can be switched and aligned automatically. It can operate over different configurations that spans a variety of q-ranges; WAXS, SAXS, MSAXS, and USAXS. Accessories include a low-noise flow cell for dilute or low scattering samples, BioCube for low volume samples, capillary holder for liquid samples, gel and powder sample holder, GISAXS sample holder for thin film and surface analysis, heating stage, and humidity stage.

2019 National Chemistry Week

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Last Thursday, October 17, about 60 people of all ages were in 555 Buehler Hall at the University of Tennessee, Knoxville Department of Chemistry for Al Hazari’s 29th Annual “Magic of Chemistry Show.” This year’s theme was “Marvelous Metals!”

The audience came from all over the East Tennessee area. In attendance were local American Chemical Society members, faculty and staff members, area K-16 students and teachers. Emeritus Professor Bob Compton and his family attended the show.

Hazari had help from Avery Blockmon, third year grad student, and John Hymel, senior undergraduate student. The department’s professor Ben Xue was a “guest star” lit up the evening with a fiery natural gas – soap bubble demonstration.   

On Tuesday, October 17, a preview of the show was presented on Knoxville’s WBIR TV-10 “Live @5 @ 4” program.

Vogiatzis’s Hot Paper

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Metal-organic frameworks (MOFs) are a class of hybrid inorganic/organic materials with exceptional properties that have been used in many chemical applications such as catalysis, gas separations, and sensors.

For the first time, gas‐phase catalytic activity occurring at the metal nodes of a crystalline MOF was reported in a recent collaborative work among the groups of Professor Kostas Vogiatzis (theory), and Professors Donna Chen (catalysis, characterization) and Natalia Shustova (synthesis) from the University of South Carolina. 

Vogiatzis said, “Also, this study shows for the first time a rhodium at oxidation state II can be introduced in a MOF. “

The electronic structure of the heterobimetallic Cu-Rh node and the reaction mechanism of the hydrogenation of propylene was elucidated by post-doctoral associate Rajesh Thayalan in Professor Vogiatzis research group.

The conclusions of this collaborative work were published in Angewandte Chemie International Edition in an article that was selected as “hot paper” by the editor.