Metal-halide perovskites are crystalline materials that work as a semiconductor in both Light Emitting Diodes (LEDs) and solar cells. In general, perovskites possess the formula ABX3. For this project, the A site is an organic molecule such as Methylammonium (MA), the B site is Lead, and the X site is Bromide. While perovskites are easily fabricated, their crystal size and number of defects present are challenging to control. Defects cause LEDs to be less stable and/or less photoluminescent (bright) and cause solar cells to be less efficient at converting light to energy. One approach to reduce the number of defects is to use ionic liquids during perovskite formation. Ionic liquids are compounds made of ions in the liquid state due to a low melting temperature. They can be added to the perovskite precursor solution to slow down the crystallization process so that fewer defects are created. The goal of this project is to create new metal halide perovskites in the presence of selected ionic liquids, evaluate their structure and photophysical properties, with the long-term goal of creating new LEDs that are both stable and efficient.

In this project, cetyl-ionic liquids (cetyl meaning 16 carbon chains) were investigated for their effects on perovskite structure and light emission. The three ionic liquids were investigated: [C16-mim]Br (referred to as "IL1"), [C16-py]Br ("IL2"), and [C16-C1pyrr]Br ("IL3"). Variations on the addition method of ionic liquids to the perovskite precursor were studied as well. It was hypothesized that the inclusion of cetyl-ionic liquids will protect the perovskite films from the environment (increasing stability) by providing a hydrophobic layer on the surface and will improve the electronic properties by filling in pinholes that cause defects. It is found that perovskite films with IL3 are more photoluminescent than the perovskite films formed with IL1, IL2, or no IL (control). Preliminary experiments varying the addition method of IL3 during film formation have shown that the perovskite films are brightest when IL3 is added to both the precursor and the antisolvent layers at the beginning of the fabrication process. These results, along with detailed structural characterization of a given perovskite film, will be discussed in this presentation.

This project aims to incorporate unnatural amino acids into proteins using an ortogonal pair composed by a leucyl synthetase from Methanobacterium thermoutotropicum (MLRS) and tRNA from Halobacterium sp. NRC-1 (HL-TAG3). A plasmid called pRCG was designed to contain a cat-upp fusion gene with amber stop codons at permissible sites of the chloramphenicol acetyl transferase protein (CAT). Three variations of the pRCG plasmid were tested: Q98TAG, D111TAG, and a double mutant containing both mutations. To study the amber codon suppression ability of the mutants, a functional leucyl-tRNA synthetase lacking the editing domain was tested for the incorporation of its endogenous amino acid using the three pRCG variants. To show that the amber stop codon is being suppressed, E. coli GH371 cells must survive when grown in the presence of leucine and chloramphenicol because the full-length CAT is expressed. In contrast, when grown in the presence of 5-fluorouracil (5-FU) and leucine, cells will not survive because the MLRS produces a full-length uracil phosphoribosyl transferase protein (UPRT) that converts 5-FU to a toxic product, causing the cells to die. Only Q98TAG or D111TAG mutant was able to suppress the amber stop codon when E. coli GH371 cells were grown in the presence of leucine under positive and negative selection conditions. The Q98TAG variant showed higher suppression ability. A library of MLRS with five randomized amino acids in the active site was designed and selected using the pRCG Q98TAG system and two unnatural amino acids (UAAs): 4-nitro-1-phenylalanine and 2-amino-3-(5-(dimethylamino)naphthalene-1-sulfonamide)propanoic acid (Dansyl-Dap). The obtained variants are currently under study to test their ability to incorporate these UAAs into a model protein called Z-domain

Catalase is one of the most efficient antioxidants metalloenzymes in biology responsible for the decomposition of hydrogen peroxide into water and oxygen. The desired antioxidant activity of catalase for medical and industrial application has inspired the study of metal-based mimics of catalase activity. However, very few of these studies explored iron-based mimics, their mechanism of action and the impact of the metal center environment on the activity of the complex. In this study, the first goal is to investigate pyridine containing macrocyclic Fe (III) complex (L1) as catalase mimic. Mass spectroscopy and UV-Visible spectrophotometry were used to follow the mechanistic activity of FeL1. The second goal is to evaluate the impact of adjusting the electronic properties (L2 and L3) and the structural rigidity (L1 and L4) of the ligand on the activity of the complex. Cyclic voltammetry, X-ray structural analysis, potentiometric titration, and UV-Visible spectrophotometry were conducted to characterize and study the properties of all the complexes. Kinetic studies following the initial rate method and TON studies were conducted to compare their activity.

Three b-branch substituted macrocycles featuring a b-branched amino acid linked acetal, a trans-hydrazone, and dimethyl amine were synthesized via acid condensation to yield homodimer macrocycles near quantitative yield without need for further purification. Previous attempts at the dimerization of triazine monomers utilized glycine or b-alanine that do not contain steric bulk. Here, L-valine, L-threonine, and L-isoleucine were used to probe the effects of steric bulk upon macrocycle formation. The resulting macrocycles are symmetrical species that are characterized by 1H-NMR, 13C-NMR, 1H-COSY spectroscopy, and 1H-rOesy spectroscopy. The symmetrical macrocycles containing valine exists as one species while threonine and isoleucine macrocycles exist as two isomers in a 9:1 and 6:4 ratio respectively. All three macrocycles exist as one rotamer state out of four possible. The minor isomer of the threonine macrocycle has an inconclusive rotamer state where the isoleucine macrocycle shows the same rotamer state as the major isomer. Well-tempered MetaDynamics Simulations tell us the rotamer state seen in the rOesy favors a folded state in all cases with barriers to interconversion decreasing as size of the side chain increases.

Cancer is a disease worldwide, and every year millions of people are diagnosed with it. Platinum compounds play an important role as anticancer agents. Their ability to bind to DNA in the nucleus (by a process known as intercalation within DNA base pairs) result in DNA damage and cell death. Unfortunately, these platinum-containing compounds lack specificity toward cancer cells and attack normal healthy cells that results in significant side effects as a consequence (loss of hair, nausea, among others).
Drug carriers (inert structures that house a given drug) that can deliver relatively large amounts of one of these drugs in a small volume (which are often chemically metastable) with some degree of specificity toward the tumor (thereby sparing the healthy cells) are clearly desirable. Our research group has developed a straightforward method to produce a well-defined nanoscale drug carrier known as silicon nanotubes (SINTs), along with a way to incorporate platinum on their surface using (3-Aminopropyl) triethoxysilane (APTES) as a functional arm. These silicon nanotubes have attracted great attention in applications relevant to diagnosis and therapy, owing in part to its biocompatibility and biodegradability in cells.
Once inside the cell, platinum is released slowly, thus allowing an interaction with DNA. Our previous results using this technology showed significant toxicity on a type of cancer cell known as HeLa. While these findings are promising, specificity has not yet been achieved.
Cancer activates signaling pathways that translates on overexpression of specific proteins/receptors. Particularly, folate receptors (FR) are present in 90-98% of ovarian, prostate, uterus, breast, as well as some adenocarcinomas. FR expression is very limited in normal cells and generally not accessible to blood flow which makes it a suitable and promising system to target cancer. These receptors are glycopolypeptides that present a high affinity for folic acid (FA). We propose to incorporate folate to our silicon-based Pt nanoparticles to enhance selectivity.
A viable strategy has been identified, involving the conjugation of a molecule known as glutathione to act as a linker to the surface of the silicon-based platinum nanoparticles through N-Hydroxysuccinimide (NHS) activation, followed by substitution with folic acid. This presentation will highlight some of our recent progress in this approach.

Oxidative stress is caused by the accumulation of reactive oxygen species (ROS) in the body and is a key player in many maladies, including neurological diseases like Parkinson’s and Alzheimer’s disease. Superoxide dismutase (SOD) enzymes are capable of transforming the common ROS molecule superoxide (O2-) into less toxic species such as H2O2 or O2, thus protecting the body from harmful reactions of superoxide. Synthetic metal complexes show promise as SOD mimics and can be effective alternatives to therapeutic dosing of SOD enzyme for oxidative stress. In this work, we present a series of 12-membered tetra-aza pyridinophanes (Py2N2) and the corresponding copper complexes with substitutions on the 4-position of the pyridine ring. The SOD mimic capabilities of the Cu[Py2N2] series were explored using a UV-Visible spectrophotometric assay. Spectroscopic, potentiometric, and crystallographic methods were used to explore how the electronic nature of the 4-position substitution affects the electronics of the overall complex, and the complex’s activity as a SOD mimic. This work is an initial step toward developing these Cu[Py2N2] complexes as potential therapeutics for neurological diseases by mimicking SOD’s capabilities and protecting the body from oxidative stress.

Small molecular probes, dyes with photophysical properties correlating with various environmental physical properties, such as polarity, pH, viscosity, and temperature, are widely used in various areas of analytical, biological, and material sciences.

This poster will describe spectroscopic behavior of pyrrolyl-squaraine dyes in various types of media (i.e., molecular, ionic and deep-eutectic solvents, and micelles) using a variety of spectroscopic techniques (i.e., absorption, fluorescence, nuclear magnetic resonance and circular dichroism). Some aspects related to the synthesis of these dyes will be presented as well.

Due to the high demand of proteins in the pharmaceutical and biotechnological fields, the number of available proteins obtained through DNA recombinant techniques has significantly increased. The high demand for protein production has motivated a need for more efficient and sustainable methods for protein purification in downstream processing. Currently, chromatography is the primary method used in protein purification. However, it is generally regarded to be expensive and cannot be easily applied to large amounts of protein raw materials.
Preparative protein crystallization is regarded as a promising alternative for protein purification as it does not suffer the limitations of chromatography. However, protein crystallization is a complex, not well understood process. Hence, its implementation requires extensive crystallization screening with moderate success. In this poster, a new strategy for enhancing protein crystallization from metastable protein-rich droplets generated by liquid-liquid phase separation (LLPS) is outlined. This strategy requires the use of two additives. One additive promotes LLPS (inducer), and the other additive (modulator) alters the composition of droplets and their thermodynamic stability. This strategy is supported by our recent work on lysozyme in the presence of NaCl (inducer) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonate (HEPES, modulator).

Transparency in business operations has increased across industries as consumer demand for companies to share their sustainability practices has expanded. Because of this, businesses have begun to reinvigorate earlier operational goals that involved actions to improve environmental protection, social equity, or economic stability to align with the three conceptual pillars of sustainability – economy, society, and environment. The purpose of this research is to add to the expanding body of scholarly work investigating methods for operationalizing sustainability research and build on a method for visualizing and analyzing the extent to which sustainability practices align with each pillar of sustainability. To illustrate this method, we examined the websites of 164 manufacturing companies that have their headquarters in one of Texas’s four largest metropolitan statistical areas (MSA; i.e., Austin-Round Rock-Georgetown, Dallas-Fort Worth-Arlington, Houston-The Woodlands-Sugar Land, and San Antonio-New Braunfels). We used a quantitative content analysis approach to document occurrences of sustainability practices related to each entity’s business operations. We sorted these observations into one of the three pillars of sustainability and then visualized the occurrences across the four MSAs. The results show how location can influence manufacturer’s sustainability efforts, and that the integration of sustainability practices remain nascent despite consumer demand for transparency and sustainability.

It is generally acknowledged that natural resources are preferentially selected by wildlife and it is only when these resources are unavailable or limited that a species will seek a less preferable option or alternative. While the use of anthropogenic structures and features by wildlife in disturbed habitats or urban environments is well-documented, the use of such resources in natural and semi-natural habitats is not. To address this, we explored the importance of artificial water sources for bats in a semi-natural habitat. We conducted acoustic monitoring surveys at two swimming pools at tourist lodges on the Amakhala Game Reserve in South Africa from 2018 to 2021 and behavioral observation surveys in June of 2021. From the data collected, we determined species-specific activity within proximity to the pools, foraging activity (identified by approach phase calls and feeding buzzes), and drinking activity (identified by the occurrence of drinking buzzes). Seven of 23 locally known species have been identified at the swimming pools, at which both foraging (~1% of calls) and drinking activity (~5%) has been recorded. This study provides insights into how anthropogenic features could be of value to wildlife in a semi-natural habitat.