Chemistry

Alice BlackBear, alice.blackbear@csupueblo.edu
Colorado State University Pueblo, with Dr. Max Wallace

Structure-Photoluminescent Property Relationships in Sb3+-Doped 0D Hydrated and Vacancy-Ordered Perovskites: Effects of Cation Substitution, Dimensionality, and Temperature
Sb3+-doped perovskite derivatives A2InCl5·H2O (A = Rb+, Cs+) and vacancy-ordered Cs4MnBi2Cl12 have garnered attention as luminescent phosphors due to their high quantum yields and tunable emission properties. This study explores three main objectives: first, evaluating how different A+ cations and their solid solutions influence the structure and photoluminescent behavior of these materials; second, synthesizing nanoscale forms to assess the impact of particle size on photoluminescence quantum yield (PLQY); and third, investigating the effect of temperature on structural and optical properties. Bulk samples of Sb3+-doped A2InCl5·H2O and Cs4MnBi2Cl12 were synthesized via solvent precipitation and microwave-assisted techniques, while nanoscale versions are being developed using ligand-assisted reprecipitation (LARP) and hot injection (HI) methods, with structural and optical characterization performed using powder X-ray diffraction (PXRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and photoluminescence spectroscopy. Cs4MnBi2Cl12 adopts a rhombohedral R-3m structure at room temperature but appears to undergo a transformation into a cubic Fd-3m phase near liquid nitrogen temperatures, correlating with notable shifts in photoluminescent behavior. This study is ongoing, and current findings offer early insight into how compositional and structural tuning can meaningfully influence luminescent behavior, suggesting promising directions for further development of these materials in optoelectronic applications.
 

Arriona Davis, pdavis7@harding.edu
Harding University, with Dr. Jaime Murphy and Dr. Kanembe Shanachilubwa

Using Deoxyribose Assay to Measure Antioxidant Capabilities of Methionine
Oxidative stress results from an imbalance between reactive oxygen species (ROS) and antioxidant defenses, contributing to cellular damage and diseases such as cancer and neurodegeneration. Among ROS, the hydroxyl radical (•OH) is highly reactive and particularly destructive to DNA, lipids, and proteins. Antioxidants neutralize ROS and help maintain cellular integrity, but not all antioxidants target hydroxyl radicals effectively. This study hypothesizes that methionine, a sulfur-containing amino acid, can act as a hydroxyl radical scavenger. To test this, the deoxyribose assay was used-an in vitro method based on the Fenton reaction, which generates hydroxyl radicals that degrade deoxyribose sugar. Methionine's effectiveness was compared to glycine, a non-sulfur-containing amino acid, to assess the role of its sulfur group.

Results suggest that methionine reduces oxidative damage more effectively than glycine, supporting its potential as ascavenger antioxidant. These findings contribute to understanding sulfur-based antioxidant mechanisms and their applications in mitigating oxidative stress. Ongoing analysis will further clarify methionine's role in ROS neutralization and its biological significance.
 

Joseph Hinh Duong, jcd7124@mavs.uta.edu

University of Texas at Arlington, with Dr. Mark W. Pellegrino

Exploring the Repression of the Mitochondrial UPR by P. aeruginosa FadE2 Using a Forward Genetics Approach

Mitochondria, commonly referred to as the powerhouse of the cell, are responsible for a rich assortment of corecellular functions that make them vital for cell viability and survival. Cells employ the mitochondrial unfolded protein response (UPRmt) as a means of preserving mitochondrial function. In C. elegans, the UPRmt also supports host resistance during bacterial pathogen infection by promoting innate immunity. Indeed, the UPRmt is required for hostsurvival during infection with Pseudomonas aeruginosa, an opportunistic pathogen that targets mitochondrial functionand activates the UPRmt. Intriguingly, P aeruginosa can also repress the UPRmt during chronic infection. We previously discovered that P aeruginosa FadE2, an acyl­ CoA dehydrogenase involved in the catabolism of branched-chain amino acids and fatty acids, was involved in the repression of the UPRmt. Consistently, loss of FadE2 function in P aeruginosa enhanced UPRmt signaling and extended host survival during infection. However, the mechanism by which FadE2 represses the UPRmt is unknown. Here, we employed an unbiased forward genetics screen to identifyfactors in P aeruginosa which mediate the repression of the UPRmt by FadE2. A transposon insertion library was created in the P aeruginosa FadE2 loss-of-function background to isolate suppressor mutants that restored UPRmt repression and reduced host survival. We isolated several of such suppressor mutants which we are in the process ofclassifying using whole genome sequencing. We will report on the findings from our screen during the conference proceedings.