Psychological stress afflicts a considerable portion of the world’s population, and is linked, as both a risk factor and potential contributor, to dementia-related brain dysfunction in diseases such as Alzheimer’s disease (AD). The brain dysfunction in AD is marked by an increase in Amyloid-beta, the protein responsible for plaque deposition in the brain. The present study aimed to explore alterations in the production of amyloid-beta in response to stress and inflammation. Specifically, we were interested in social isolation stress- and inflammation-induced differences in cognition and amyloid-beta production in male and female mice. Mice were subjected to acute social isolation (6 days) and chronic isolation (28 days) or control group housing. Results revealed that exposure to both acute and social isolation can lead to an exacerbated inflammatory response to lipopolysaccharide (LPS). Subsequently, we examined if the stressors altered amyloid-beta production following the same inflammatory stimulus. Animals received LPS or saline injections once per day for seven consecutive days after the completion of either stress protocol or group housing. The contextual fear conditioning paradigm (CFC) was utilized to assess cognition. Brain tissue extractions were performed to quantify amyloid-beta protein levels. It is hypothesized that isolated animals will demonstrate cognitive deficits in CFC as well as increased brain amyloid-beta following LPS injections.

Mercury (Hg) is a toxic heavy metal that has contaminated all aquatic food webs and can pose a health risk to aquatic predators. Piscivorous birds are apex predators in aquatic systems that are exposed to mercury through the consumption of Hg-contaminated fish. Although there is extensive data on Hg concentrations in fish, the data on Hg concentrations in birds is relatively limited. I used a previously published relationship between Hg concentrations in piscivorous bird blood and Hg concentrations in prey fish to estimated Mg concentrations in the blood of four species of piscivorous wading birds in the south central U.S. [Little Blue Herons (Egretta caerulea), Green Herons (Butorides verescens), Great Egrets (Ardea albus) and Great Blue Herons (Ardea herodias)] from the concentration of Hg found in bluegill (Lepomis macrochirus). Estimated Hg concentrations in bird blood increased with the size of prey fish consumed and was lowest for Little Blue Herons and Green Herons, intermediate for Great Egrets and highest for Great Blue Herons. Estimated Hg concentrations in bird blood was greatest in ecoregions where conifer-adjusted mercury deposition was highest. Mercury risk to bird health varied with bird species and increased with Hg deposition. Little Blue Herons, Green Herons, Great Egrets and Great Blue Herons were at some level of risk in 14, 36, 86 and 100% of ecoregions, respectively. The threat of Hg to the health of piscivorous wading birds may not be unique to south central U.S. and may extend throughout the southeastern United States due to high Hg deposition and extensive forest coverage.

Hydrilla verticillata is an invasive aquatic weed in the United States (U.S.) that has recently
developed resistance to the herbicide fluridone. In this study, we utilized genome walking and
quantitative real-time PCR to investigate the phytoene desaturase (PDS) gene copy number of
hydrilla samples with different ploidy levels. We asked 1) if copy number simply corresponds to the
ploidy level, and 2) if there is increased PDS copy number in resistant populations due to gene
duplication. Using qPCR and microsatellite loci to compare PDS copy number between diploid,
triploid and tetraploid samples, we found that diploid hydrilla from Africa showed higher PDS copy
number than triploid populations from the U.S. The results also indicated that there was no
significant difference in PDS gene copy numbers between the fluridone-resistant and -susceptible
triploid populations. Our study suggests that PDS amplification may not be a mechanism
responsible for fluridone resistance in hydrilla.

Methylmercury (MeHg) is a toxic environmental contaminant found in all waterbodies on Earth. Aquatic emergent insects, such as mosquitoes and midges, can transfer MeHg from waterbodies to terrestrial ecosystems. Terrestrial shoreline spiders consume aquatic emergent insects and become contaminated with MeHg. Methylmercury-contaminated spiders can pose a risk to songbirds that consume terrestrial spiders. Because shoreline spiders have MeHg concentrations that reflect MeHg contamination of nearby aquatic ecosystems and are an important source of MeHg to songbirds, they have been proposed as a biosentinel species that can be used to estimate MeHg contamination of waterbodies. In this study, I used long-jawed orb weavers (Tetragnatha sp.) as a biosentinel species to examine MeHg contamination along the Clear Fork and the West Fork of the Trinity River, Fort Worth, Texas. The objectives of this study were to: 1) evaluate MeHg contamination in long-jawed orb weavers from two forks of the Trinity River, and 2) determine if the concentrations of MeHg in the spiders pose a risk to songbirds that feed on spiders. I collected 101 and 105 spiders along the Clear Fork and the West Fork, respectively. I used a Direct Mercury Analyzer to determine the total Hg concentration of the long-jawed orb weavers. Because MeHg is the primary species of mercury in spider tissues, I used total Hg as a proxy for MeHg. All spiders were contaminated with MeHg, with spiders along the Clear Fork having significantly higher MeHg concentrations than spiders along the West Fork. Methylmercury in spiders increased with spider size along the Clear Fork. Concentrations of MeHg in spiders along the Clear Fork and the West Fork were high enough to pose a risk to the physiology of nestling songbirds that feed on spiders.

Understanding bacterial virulence is important because it provides insight into the molecular basis behind bacterial infections. With the decreased efficacy of antibiotics due to the development of drug resistance, this knowledge could be used to identify specific targets for new pharmacological targets thereby strengthening our arsenal against these pathogens. Currently, our main mechanism by which to evaluate in vivo virulence is the mouse model (Mus musculus). While this model is effective, there are substantial ethical and resource constraints associated with vertebrate use. In order to provide alternative in vivo testing models, this study investigated the invertebrate wax worm larvae, G. mellonella, as an in vivo infection model for B. anthracis. To validate the ability of G. mellonella to discern attenuated bacterial strains, previously identified virulence mutants were constructed and assessed. This model proved capable of distinguishing between virulent and avirulent strains. Next, we tested whether G. mellonella could identify novel virulence mutants. A small collection of transposon mutants was screened for deficits in reactive oxygen species (ROS) survival and iron acquisition using in vitro screens. This yielded 10 attenuated mutants. These mutants were then assessed in G. mellonella and 2 were found to have an in vivo phenotype. These results demonstrate the potential effectiveness of G. mellonella as a future infection model and could increase the efficiency in the identification of novel bacterial virulence mutants.

Dreissena polymorpha, zebra mussels, are an invasive species of freshwater bivalves that have recently spread into bodies of water across North America via the Great Lakes. Zebra mussels are mainly spread throughout the United States by their free-swimming larvae called veligers that are moved from waterbody to waterbody by human boat traffic, attributing to the success of their invasive spread. Once an adult zebra mussel population is established, they proliferate quickly and cause many problems to the ecosystem by their efficient filter feeding abilities. They also cause damage to boating and water treatment equipment by tightly attaching to many hard surfaces. Zebra mussels have recently entered many Texas waterways, indicating that they have possibly adapted to conditions outside of originally expected for a cold water species that are not representative of the Great Lakes region. The focus of this study was to look at various environmental factors which may affect zebra mussel survival and reproduction including temperature and the effects of a copper-based molluscicide, EarthTec QZ, as a potential mechanism of control. Zebra mussel survival and reproductive success were examined in various experiments to gain an overall understanding of the effects at all zebra mussel life stages.

Methylmercury (MeHg) is an aquatic contaminant that can be transferred to terrestrial predators by emergent aquatic insects such as odonates (damselflies and dragonflies). We observed the effects of time on odonate-mediated MeHg flux (calculated as emergent odonate biomass MeHg concentration) in 20 experimental ponds and the potential risk to nestling red-winged blackbirds (Agelaius phoeniceus) posed by consuming MeHg-contaminated odonates. Emergent odonates were collected weekly from ponds containing four emergent traps per pond over an 9-mo period (February–October 2017). The MeHg flux from damselflies, aeshnid dragonflies, and libellulid dragonflies began in March and peaked in May, June, and July, respectively, and then declined throughout the rest of the summer. Nesting of red-winged blackbirds overlapped with peak odonate emergence and odonate-mediated MeHg flux. Because their diet can be dominated by damselflies and dragonflies, we tested the hypothesis that MeHg-contaminated odonates may pose a health risk to nestling red-winged blackbirds. Concentrations of MeHg in odonates exceeded wildlife values (the minimum odonate MeHg concentrations causing physiologically significant doses in consumers) for nestlings, suggesting that MeHg-contaminated odonates can pose a health risk to nestling red-winged blackbird.

Alzheimer’s Disease (AD) is a neurodegenerative disease that is characterized by deficits in learning and memory. AD pathology is associated with neuronal death through the accumulation of amyloid beta (Aβ) plaques in the synapses. Our lab has previously demonstrated that Lipopolysaccharide (LPS), a component of gram-negative bacteria, induces an inflammatory response that increases Aβ found in the brain. Dendritic spines are projections on dendrites that may or may not be synapsing with an axon. Previous research indicates that there is a correlation between the number of properly functioning synapses and the number of dendritic spines. In this study, LPS was administered to induce inflammation, stimulating Aβ production. We then quantified dendritic spine density in order to compare dendritic spine density in the hippocampus of both LPS- and saline-treated groups. Contrary to our hypothesis, we saw a non-significant increase in dendritic spine density following LPS treatment, when compared to saline controls.

There has been mounting concern from both scientists and the public regarding the presence and biological effects of emerging contaminants (ECs) in the environment. ECs can be defined as contaminants that are not currently subject to routine monitoring programs or regulatory standards, but that have the potential to cause adverse environmental or human health effects. These pollutants are being found in increasing levels in aquatic environments, and as such, the possible health impacts of these contaminants have become a growing focus of scientific research. Some classes of ECs, especially those that disrupt neurological development or thyroid hormone levels, have the potential to alter the growth, development, and function of the eyes. For many organisms, eyesight is crucial to survival as it allows them to avoid danger, obtain food, and perform many other important activities. However, reliable methods for testing the effects of ECs on vision are scarce, so the full impact of many ECs remains unknown. As such, this project aimed to determine dependable ways to measure visual development and function in the fathead minnow, a small fish frequently used to screen for chemical toxicity and adverse effects. We found that the feeding assay was a straightforward and promising option for measuring vision because it estimated the average prey capture ability of a group in a relatively short amount of time. We also found that the optomotor assay, while compelling, presented no significant differences between groups for the variables tested. However, there were practical differences observed throughout the trials, indicating that although the assay is complex, further testing and development could transform it into a reliable source of data.

Zebra and Quagga mussels are aquatic and highly invasive freshwater bivalve molluscs native to Eurasia. They have spread at an exponential rate into bodies of water throughout the country by means of our interconnected waterway. Prior analysis of their distribution has determined a consistent global pattern in which a population of zebra mussels initially invades a body of water and subsequently, a population of quagga mussels is established in the same region. Despite differential habitat preferences, both species have been found to live and reproduce in the same location. Since both species exhibit broadcast spawning as a reproductive mechanism, the potential for hybridization exists; this potential was analyzed via evaluating the initial fertilization and early embryonic cleavage stages required for production of viable hybrid offspring. A series of hybridization crosses were performed and compared against a control. Fertilization events observed and analyzed included motility and chemotaxis, the acrosome reaction, sperm binding and entry into the egg cytoplasm, and finally cleavage and early development. Inability to produce viable offspring suggests a hybridization-block has been established between the two species at the level of fertilization or early development.

Some classes of endocrine disrupting compounds in the environment have the ability to alter thyroid function. Such thyroid disrupting compounds are known to influence growth and development, but recent studies suggest that thyroid disruption can also have adverse effects on reproduction. A recent study in the Jeffries lab demonstrated that early-life stage thyroid disruption caused decreased reproductive output in fathead minnows (Pimephales promelas), even after a prolonged period of depuration. However, the mechanisms connecting early life stage thyroid disruption to altered reproduction during adulthood remain elusive. This study sought to determine whether alterations in reproductive success following thyroid disruption were a result of male or female reproductive performance in an effort to narrow potential mechanisms by which thyroid disrupting compounds alter reproduction. The results of this study bring insight to the underlying cause of decreased reproductive output following thyroid inhibition.

Carnivorous plants occupy nutrient-poor soils and have evolved traits that allow them to obtain nutrients by capturing and digesting insects. The pale pitcher plant, Sarracenia alata, uses passive pitfall traps to capture their insect prey. Although studies have examined prey composition for S. alata, it is unknown whether this species is selective in prey capture or whether it captures insects in proportion to their abundance in the environment. The purpose of this study was to compare prey capture of S. alata pitchers with the available insects to determine whether this species is selective in prey capture. The available insects were sampled using artificial sticky traps in the vicinity of the pitchers. The insects in the study were identified first to the taxonomic level of order and then further identified to "morphospecies" as a means of examining preference on a finer scale. The relative proportions of insects in specific orders differed between artificial traps and plants. Although dipterans were a major component of capture in both artificial traps and plants, the relative proportions of morphospecies differed between the two. These results support the hypothesis that S. alata is selective in its prey capture, but further studies are needed that use different methods of measuring the available insects in order to avoid potential bias.

Our team will answer the question how Penicillium mold grows in a microgravity environment versus Earth’s gravity. This question answers or sparks several other questions such as is it a viable solution for some antibiotics in space or how do antibiotics like penicillin work in the body in space. Will it grow more or will it be the same or maybe grow less? The purpose of our experiment is to provide a viable solution to some bacterial infections in space. Bacteria in space tends to act more violently so maybe good bacteria or mold will act more furiously to kill those bacteria. Our hypothesis is that it will grow better. This is based off of the fact that in an earlier SSEP experiment the polymers absorbed more water. Which might be the same for organisms like mold so it would make it easier to absorb water. Plus with lower gravity organisms tend to grow larger at least that is many scientist hypotheses. So since there is practically no major gravity or forces in space may be the mold will grow larger than usual. Our group believes this based on the fact that we have researched.

Our experiment is about diabetes and Humalog synthetic insulin crystallization in a microgravity environment. We feel like this is a good experiment to design because we could find out if there is a way to prevent crystallization of insulin, especially if we understand how it happens in microgravity. When insulin crystallizes, the bacteria that usually makes it viable stops working. This would cause it to be ineffective for patients in dire need of this medication. To complete this experiment we are going to keep the insulin in a type 1 FME at the International space station (ISS) at above 65℉ to see if it crystallizes within a certain amount time. We will keep the experiment refrigerated at or below 40℉ during transportation to the ISS and again on arrival back to Earth’s gravity. Refrigeration slows the crystallization growth and this is how it is stored on Earth. Keeping our experiment refrigerated during transportation is an important step because the insulin crystallization growth should only be measured while in microgravity. We will be conducting the same experiment, using the same time frame and refrigeration needs before and after, for our earth bound experiment.

Our experiment is how well will a hornwort plant purify polluted water in microgravity. We will see how it will purify at the same rate as it does in full gravity. We chose this plant because they can purify water and they grow at a fast rate. This will help astronauts because if they run out of water they can grow hornwort even if the only water they have is polluted. Also, it will help them to have purified water if their water system breaks down. The hornwort plant will be growing on the way from Earth to the ISS. The experiment will be purifying the polluted water in microgravity for 5-6 days. Then the formalin will be added to the plant to stop its growth and preserve the sample. We are polluting the water with Cyanobacteria, which is more commonly known as blue green algae. We will know it has worked if the polluted water has become purified after it has been tested.

Previous studies, including those in the Jeffries lab, have shown that female animals are able to fight and survive infection better than males. However, the underlying cause of this difference remains unclear. Because many differences between males and females are due to differences in sex steroid hormone (e.g., estrogen, testosterone, etc.) concentrations, it is possible that differences in immune function are also due to such differences in hormone levels. The objective of this study is to uncover the role of sex steroid hormones in the immune response of fathead minnows (Pimephales promelas). Because females exhibit better pathogen resistance than males, it is hypothesized that estrogen (a “female” hormone) enhances immune system function. The results of this study provides insight into the potential crosstalk between the reproductive and immune systems, as well as a better understanding of the role of sex hormones in the organism.

The fathead minnow (Pimephales promelas), a small fish model often used to screen for reproductive endocrine disrupting compounds, has recently been used by some investigators to screen for chemicals with thyroid disrupting capabilities. However, it is uncertain how known thyroid disruptors affect various markers of thyroid disruption in this species. This study aimed to fill this gap in knowledge by assessing the sensitivity of endpoints known to be responsive to thyroid disruption in other closely-related species in larval fathead minnows. In addition, we sought to uncover how the timing and length of exposure influenced the response of these endpoints. To accomplish these objectives, larval fathead minnows were exposed to various doses of propylthiouracil (PTU; a known thyroid disruptor) and thyroxine (T4; a known thyroid stimulant) for 35 days. Several metrics indicative of alterations in thyroid hormone status (e.g., thyroid related gene expression, growth, thyroid cell follicular height, etc.) were measured on day 7, 21, and 35. The results of this study provide valuable information that can be utilized in developing fathead minnow thyroid disrupting chemical screening assays.

Habitat maps derived from remotely sensed data are strong predictors of wildlife distributions, outperforming traditional on the ground vegetation structure surveys. Texas Parks and Wildlife created a statewide habitat map in 2014 featuring 398 vegetation classes to 10-meter resolution. The Great Trinity Forest is the largest urban forest in the United States, with 3,000 continuous hectares within the city of Dallas. As part of our wider study of the forest’s wildlife, we edited Texas Parks and Wildlife’s habitat to more accurately and meaningfully reflect habitat distinctions in the Great Trinity Forest. First we adjusted the locations and boundaries of waterways to reflect changes in their location over the past four years. Then we reclassified the bottomland hardwood forest habitat type (BHF) to reflect different succession stages of forest growth. Using LIDAR and aerial images we calculated canopy heights and reclassified BHF using those heights as primary BHF, secondary BHF, or early successional bottomlands.

Methylmercury (MeHg) is an environmental contaminant that can have adverse effects on wildlife. Because inorganic Hg is converted to MeHg primarily in aquatic ecosystems, studies of MeHg contamination of food webs have historically focused on aquatic organisms. However, recent studies have found that emergent aquatic insects (e.g. mayflies and dragonflies) can transport MeHg to terrestrial predators like songbirds, and this could have implications for species in decline such as Red-winged blackbirds (Agelaius phoeniceus). Red-winged blackbirds are odonate (dragonflies and damselflies) predators, and odonates can make up 50 – 90% of a Red-winged blackbird’s diet during the breeding season. Red-winged blackbirds have declined throughout their range by 30% over the last 50 years. Their decline is due in part to loss of wetland habitat, but the consumption of MeHg contaminated prey items could also be having an effect. Several studies have reported MeHg contamination of Red-winged blackbirds, and yet, the potential effect of diet on MeHg contamination in Red-winged blackbirds has not been studied. I collected data on blood MeHg level of Red-winged blackbird nestlings and the emergence rate of odonates during the summer of 2017 at the Eagle Mountain Hatchery Experimental Pond Facility in Tarrant County, Texas. I used the ArcGIS Space Time Cube to identify spatiotemporal hot spots of nestling MeHg level and odonate emergence, and I used linear regression models to see how well proximity to odonate emergence hotspots predicted nestling MeHg hotspots.

Cancer is the second leading cause of death and will directly affect approximately 40% of the people in the United States over the course of their life. Chemotherapy has been shown to be an effective therapeutic strategy, but it lacks specificity, resulting in a multitude of negative side effects. Targeted therapies such as Herceptin, Iressa, and Nivolumab have shown increased effectiveness against cancer by attacking specific molecules in the target cell. For example, Herceptin inhibits the HER2 protein, which is overproduced in some breast cancer cells, and stops cell division. Biotin is an innate coenzyme for carbohydrate, lipid and protein metabolism. Certain cancer types overexpress biotin transporters on the surface of each cancer cell in order to increase biotin absorption necessary for metabolic processes. Furthermore, the intracellular environment in cancer cells is more reducing compared to non-cancer cells due to increased metabolism. Ferrocene is an iron-based organometallic molecule that has been shown to generate reactive oxygen species (ROS) in the reducing environment of cancer cells. Given that certain cancer cells absorb biotin with a higher efficiency, we hypothesize that linking biotin to ferrocene will increase the efficiency of ferrocene entering the cell and result in selective cancer cell death. Therefore, we have produced a library of biotin-ferrocene conjugates to selectively target cancer cell lines that over express biotin receptor sites. Experiments were conducted utilizing ferrocene and a variety of ferrocene-biotin conjugates (C1, C2, 2) in both cancer (MCF-7) and noncancer (HEK 293) cell lines in order to compare the relative toxicity between compounds.

Many rainbow trout (Oncorhynchus mykiss) populations exhibit partial migration, where resident and migrant individuals coexist in a single population. Due to anthropogenic, environmental, and population-specific factors, migratory individuals have been decreasing in frequency across the continental United States. Biologically, whether an individual will migrate is determined by both genetic and environmental factors. Although migration in many salmonids is known to be highly heritable, the environment plays an overriding role. Previous studies investigating the genetic basis of migration have failed to control for environmental variance and, consequently, the genes and regions of the genome underlying the development of the migratory phenotype remain unknown. We used data from a common garden experiment to identify single nucleotide polymorphisms (SNPs) significantly associated with migration in the F1 generation of a resident-by-resident and a migrant-by-migrant cross. We genotyped 192 F1 individuals on an Affymetrix SNP chip at 57,501 known polymorphic locations throughout the genome. We identified 5002 significant SNPs in the migrant-by-migrant family and 429 significant SNPs in the resident-by-resident family, using an FDR-corrected p-value of 0.01. For the migrant cross, we located significant markers associated with 28 genes whose functions are connected to pathways previously hypothesized to be important in migration. Five genes on three chromosomes were associated with migration in both familial crosses, suggesting that these regions are important in determining life history regardless of familial origin in this population. These data will be further used to develop a model to predict life history in individuals that are yet to make that determination. Understanding the genetic factors involved in the decision to migrate, through the identification of polymorphisms associated with migration, will assist fisheries managers in restoring and maintaining migratory rainbow trout populations.

The Texas horned lizard (Phrynosoma cornutum) has always been believed to be an ant specialist, especially on harvester ants. However, a population of horned lizards in south Texas seem to have a more diverse diet consisting of other insects and arachnids. The goal of this project is to build a DNA library of order Coleoptera (beetles) that are preyed upon by these horned lizards. This DNA library will be compared to DNA extracted from horned lizard scat so that we can identify which species of beetles these lizards are eating. For this process, I isolated DNA from 244 beetles collected in pit fall traps from Kenedy and Karnes City, amplified the cytochrome oxidase I (COI) gene, and sequenced it. I compared the processed sequences to those available on GenBank and BOLD (Barcode of Life Database) to identify the species of beetle.

Oxidative stress in the brain is a known contributor to the development of neurodegenerative diseases, including Alzheimer’s. The focus of this project is to target the amyloid-β plaque formations and reactive oxygen species (ROS) derived from mis-regulated metal-ions that lead to disease-causing oxidative stress. The present investigation measures both the antioxidant reactivity and metal chelating ability of 1,4,11,13-tetra-aza-bis(2,6-pyridinophane)-8,17-ol (L4).  L4 contains two radical scavenging pyridol groups along with a metal-binding nitrogen rich ligand system.  It was hypothesized that increasing the number of pyridol groups on the ligands in our small molecule library would increase the radical scavenging activity, which in turn may provide cells protection from oxidative stress.  The radical scavenging ability of L4 was quantified using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay. This was compared to other radical scavenging small molecules to evaluate the effect of the additional radical scavenging group on the antioxidant activity.  The interaction of L4 with redox active metal-ions such as copper(II) was also evaluated using the coumarin-3-carboxylic acid (CCA) assay to show the molecule’s ability to target mis-regulated metal-ions in diseased tissues. With the end goal being to develop a potential biological therapeutic agent, metabolic stability studies were also performed.

The combination of inorganic porous silicon (pSi) and flexible biocompatible polymers has been shown to yield more beneficial hybrid scaffolds for tissue engineering (i.e. use of synthetic materials to facilitate healing). PSi has a variety of tunable properties, including pore size, pore volume and non-toxic degradation. The addition of a biocompatible polymer such as polycaprolactone (PCL) can provide control over shape and serve as an additional drug delivery component.
In this work, composite materials consisting of oxidized porous silicon (ox-pSi) with a particle size of ~ 30 μm and pore size of 40-100 nm and PCL porous fibers. Porous fibers were fabricated using an electrospinning method into sheets of desired thickness (0.1-0.4 mm), fiber diameter 3-4 μm, and fiber pore size 300-500 nm. Ox-pSi particles previously loaded with the anticancer drug-camptothecin (CPT) were placed between two sheets (6 mm in diameter each) and sealed at the edges, resulting in ~65% loading of ox-pSi. Drug release from the ox-pSi particles alone and ox-pSi/porous PCL fiber composites was monitored fluorometrically in phosphate buffered saline (PBS), showing a distinct release profile for each material.
Ox-pSi/p-PCL fiber composites release a CPT payload in accordance with the Higuchi release model and showed a significant decrease in burst effect compared to ox-pSi particles only. In addition, composite evolution after 5 weeks in PBS at 37 oC was examined using gravimetry, differential scanning calorimetry (DSC), and field emission scanning electron microscopy (FESEM). Overall weight loss of the composites was about 50%, mainly attributed to pSi particles dissolution and some polymer hydrolysis. Preliminary DSC results show that high surface area porous PCL fibers are less crystalline compared to solid PCL fibers, suggesting a faster hydrolysis route.

Europium contrast agents have been extensively investigated as an alternative to typical Gd3+ species for imaging. This is due to the dual imaging modalities which can accessed dependent on the oxidation state of the europium metal center (T1 or PARACEST). To achieve these functionalities, the europium containing complex must be stable enough to support both oxidation states (+3 and +2). In collaboration with UTSW, an electrochemical investigation was completed to understand the effects of the ligand environment on the metal center as a direct result of glycine modification to the ligand scaffold, DOTA. Increasing amide functionalities in close proximity to the europium core result in a positive shift in the potential in comparison to the acetate arms associated with DOTA. Furthermore, the addition of the glycine moiety to the pendant arms results in redox activity of the ligand itself, making the ligand non-innocent in nature. Additionally, a crystal structure of Eu4 (the tetraglycinate DOTA derivative) was obtained and compared to known lanthanide complexes.