Our project focuses on Europium-doped Cerium Oxide nanotubes and their use as potential probes for bioimaging and optical sensors. Most CeO2 nanomaterials are not intrinsically fluorescent in the visible region, so these materials can be doped with rare earth ions that possess visible fluorescence. Rare earth ions that prefer the +3 oxidation state can be efficiently doped into CeO2 nanomaterials due to their similar ionic radii. Our research utilizes Europium (III) for doping, which is known for its red-orange emission and hypersensitive 5D0→7F2 transition. We choose a one-dimensional architecture for the target nanostructure because of its ideal geometry to interact with cells. A sacrificial template is employed, beginning with the synthesis of Zinc Oxide nanowires on an FTO substrate. After the nanowires are grown, a Europium (III) - Cerium (III) cycling process is performed to construct the nanotube, using the nanowire as a template.
The size and morphology of the nanotubes are measured using a Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The crystalline structure of the Europium-doped CeO2 nanotubes can be characterized using X-ray diffraction (XRD) to determine how varying Eu3+ concentration can change the XRD peaks. Their photoluminescence (PL) spectra are measured as a function of varying the percentage concentration of Eu3+. Light emission is compared as a function of dopant concentration by varying the Eu3+ concentration between 5%-15% to determine the concentration with the optimal fluorescence intensity. Ultimately, the desired characteristic fluorescence of the nanotubes enables their use in bioimaging and as optical sensors.

Every 65 seconds, someone is diagnosed with Alzheimer's disease, which is the seventh leading cause of death in the United States. A major barrier to potential therapeutics is the permeability of these molecules across the blood-brain barrier. We have developed small molecules with strong reactivity to combat the oxidative stress known to cause Alzheimer’s disease. However, the permeability is less than ideal. As a result, my goal is to produce a molecule that has enhanced permeability but retains the reactivity of the parent molecules. To achieve this, the BOILED-Egg model was used to assess different derivatives of our parent molecule, Py2N2. This model showed the differences in lipophilicity among different Py2N2 compounds and how they impact permeability into the blood-brain barrier and gastrointestinal tract. Background information on our parent molecule and its function regarding Alzheimer's development will be outlined to give a scope of what these compounds can target and how they function. Compounds with high lipophilicity reflected in the model will have schemes of synthetic synthesis for future directions.

The binding of the water-soluble porphyrin tetrasodium tetraphenylporphyrintetrasulfonate (TPPS) to bovine serum albumin (BSA) in aqueous media at room temperature can be explored for developing an analytical assay for PFAS (or “forever chemicals”) detection. Indeed, we determined that spectrophotometric detection of PFAS is optimized by exploiting competitive binding of PFAS and TPPS to BSA at pH 4.7. In this poster, we spectrophotometrically investigated BSA-TPPS binding at pH 3.0, 4.7, and 7.2. Specifically, TPPS concentration was maintained constant at 80 M in our experiments and BSA concentration was varied. Interestingly, while BSA-TPPS complexes are soluble at pH 7.2, they form insoluble precipitates in acidic conditions (pH 3.0 and 4.7) at low BSA concentration. Specifically, we find that solubility of TPPS exhibits a minimum as BSA concentration increases. We therefore developed a theoretical model that successfully describes the observed behavior of TPPS solubility. Spectrophotometric calibration curves for the determination of PFAS concentration were constructed using solutions with a sufficiently high BSA:TPPS molar ratio.

The purpose of the project is to predict the redox potential of tetra-aza macrocycle copper complexes. Density functional theory combined with a continuum solvation model was used to compute the redox potentials of 23 copper–ligand complexes. Gibbs free energies for the redox reactions were evaluated at the M06-2X/Def2-SVP/Def2-TZVPP/SMD level of theory. The predicted redox potentials agree well with experimental values for tetra-aza macrocyclic copper complexes. To examine the influence of chloride, calculations were performed for ligand systems both in the presence and absence of coordinated Cl. The correlation between the computed and experimental measurements yielded R2 values of 0.92 (without coordinated Cl) and 0.89 (with coordinated Cl), reflecting trends consistent with experimental measurements. For the complexes without coordinated chloride, the predictions further demonstrated strong accuracy, with a root-mean-square error of 30.9 mV. Overall, the result highlights this computational workflow as a practical approach for estimating the redox properties of copper complexes, redox-active systems relevant to biomimetic and medicinal chemistry.

Salt-induced diffusiophoresis is the migration of a charged nanoparticle in water, induced by an imposed directional gradient of salt concentration. This transport phenomenon has emerged as a valuable tool for particle manipulation inside porous materials and microfluidics. Micelles are a common example of nanoparticles with the crucial ability of hosting small guest molecules. Thus, micelle diffusiophoresis is important in the manipulation of small molecules. Diffusiophoresis depends on the intrinsic ability of micelles to randomly move (diffuse) in water. In this poster, we report experimental micelle diffusion coefficients for the surfactant hexadecylpyridinium chloride (CPC) in the presence of aqueous NaCl and KCl. The electrical double layer theory was successfully employed to explain the effect of surfactant and salt concentrations on the observed micelle diffusion coefficient. These data were then used to characterize salt-induced diffusiophoresis of charged micelles.