Physical Sciences and Mathematics Commons^™

Gene Vectors With Fluorescence Tracking Capabilities, Sophia Despina Angelopoulos

Browse all Theses and Dissertations

This project focuses on the optimization of benzothiazole-based chromophores to utilize them as fluorescent tags functionalized onto stimuli-responsive, or “smart,” polymers as non-viral gene delivery vectors for gene therapy applications. Blue-fluorescent emissive chromophores will allow tracking capabilities for the transfection pathway of the vector to be monitored as it delivers the DNA payload within intercellular space. The most appropriate chromophore must be covalently bound to a free amine within the vector, which is accomplished through NAS chemistry from fluorophenyl-benzothiazoles (F-BTZ-CBz) derivatives to amidated hyperbranched poly(ethyleneimine)(HPEI-IBAm0.61). HPEI is considered to be a synthetic polycation, which promotes tunable solubility through characteristics of …

Raman Spectroscopic And Quantum Chemical Investigation Of The Effects Of Tri-Methylamine N-Oxide (Tmao) On Hydrated Urea, Hydrated Guanidinium, And Hydrogen Bonded Networks, Genevieve Verville

Honors Theses

Trimethylamine N-Oxide (TMAO), guanidinium, and urea are three important

osmolytes with their main significance to the biophysical field being in how they

uniquely interact with proteins. TMAO is known to stabilize and counteract the

destabilizing effects of both urea and guanidinium. The exact mechanisms by which

TMAO stabilizes and both guanidinium and urea destabilize folded proteins continue

to be debated in the literature. Some studies suggest that solvent interactions do not

play a large role in TMAO’s stabilizing effects and therefore advocate direct

stabilization, whereas others suggest that TMAO counteracts denaturation primarily

through an indirect effect of strong solvent interactions. …

Breakthroughs In Obtaining Qm/Mm Free Energies, Phillip S. Hudson

USF Tampa Graduate Theses and Dissertations

The computation of free energy is pivotal to understanding the fundamental nature of chemical phenomena. That is, whether a specific molecular outcome occurs spontaneously or is inherently unfavorable. The need to do this with consistent accuracy begs for the use of quantum mechanical (QM) methods. However, techniques for directly computing free energy differences with QM or mixed QM/MM methods are untenable, as the computational expense is quite exorbitant. At present, the most feasible approach for obtaining QM/MM free energies is employing the so-called indirect cycle, which relies on accurately computing free energy differences between low (e.g., molecular mechanical, MM) and …

Quantum Chemical Pka Estimation Of Carbon Acids, Saturated Alcohols, And Ketones Via Quantitative Structure-Activity Relationships, Corey Adam Baldasare

Browse all Theses and Dissertations

Acid dissociation constants, often expressed as pKa values, afford vital information with regards to molecular behavior in various environments and are of significance in fields of organic, inorganic, and medicinal chemistry. Several quantitative structure-activity relationships (QSARs) were developed that correlate experimental pKas for a given class of compounds with a descriptor(s) calculated using density functional theory at the B3LYP/6-31+G** level utilizing the CPCM solvent model. A set of carbon acids provided a good final QSAR model of experimental aqueous pKas versus ΔEH2O (R2 = 0.9647) upon removal of three aldehydes as outliers. A study of saturated alcohols offered a final …

The Analysis Of Trifluoromethylbenzimidazole (Tfmbi) Crystals Using Physical Chemistry Techniques To Explain Ferroelectric And Anti-Ferroelectric Properties Of The Compound, Kanwar Bhullar

Honors College Theses

Ferroelectrics are a group of materials possessing the unique chemical property of being able to switch their electrical polarity when exposed to an electric field. This property makes ferroelectrics a promising field of study with the potential to impact various future technologies in information and energy storage, as well as quantum mechanics. Understanding molecular structures of ferroelectric (and opposite anti-ferroelectric) materials, and how they relate to the compound’s properties is essential to harnessing the potential these materials carry. The report discusses analysis of anti-ferroelectric material trifluoromethylbenzimidazole (TFMBI), by subjecting the compound to various physical and computational chemistry techniques at varying …

Voltage-Driven Polyelectrolyte Complexation Inside A Nanopore, Prabhat Tripathi

Doctoral Dissertations

This thesis investigates how a pair of oppositely charged macromolecules can be driven by an electric field to form a polyelectrolyte complex inside a nanopore. To observe and isolate an individual complex pair, a model protein nanopore, embedded in artificial phospholipid membrane, allowing compartmentalization (cis/trans) is employed. A polyanion in the cis and a polycation in the trans compartments are subjected to electrophoretic capture by the pore. We find that the measured ionic current across the pore has a distinguishable signature of complex formation, which is different from the signature of the passage of individual molecules …

Mining Uranium From Seawater: A Coordination Chemistry Approach, Nada Mehio

Doctoral Dissertations

Poly(acrylamidoxime) fibers are the current state-of-the-art adsorbent for mining uranium from seawater. However, the amidoxime group is not perfectly selective towards the uranyl cation, in particular, competition with transition metal cations remains a major challenge. In order for subsequent generations of chelating polymer adsorbents to be improved, the coordination chemistry of amidoxime-uranyl and -transition metal cation complexes needs to be better understood. While the coordination mode of amidoxime-uranyl complexes has been established in the literature, a number of amidoxime-transition metal cation complex binding motifs can be observed on the Cambridge Structrural Database. Likewise, the formation constants, or log K values, …

Interactions Of The Naphthalene Radical Cation With Polar And Unsaturated Molecules In The Gas Phase, Sean P. Platt

Theses and Dissertations

Characterizing the interactions of solvent molecules with ions is fundamental in understanding the thermodynamics of solution chemistry. These interactions are difficult to observe directly in solution because the number of solvent molecules far exceed that of ions. This lend the gas phase to be the ideal medium in the study ion-solvent interactions on a molecular level. Ionized polycyclic aromatic hydrocarbon (PAH) molecules can readily form hydrogen bonds with neutral solvent molecules in aqueous and interstellar medium. Previous research has been done for stepwise solvation of small molecules such as benzene⁺, pyridine, and phenylacetylene. The similarity in these results …

Work Function Modification Of Metal Electrodes Via Printing Of Pedot:Pss And Carbon Nanotubes, Carly A. Jordan

Browse all Theses and Dissertations

Work function tunability of metal electrodes provides a route to improving performance of organic electronic devices. Using an electrode with a different work function changes the potential barrier at the polymer/electrode interface, leading to altered device characteristics, such as turn-on voltage in light emitting diodes or series resistance photodiodes. In this work, we explore work function modification by employing solution-based conducting materials, poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT:PSS) and carbon nanotubes (CNTs), printed as overcoatings on oxidized Ni. The capability of direct write technologies, namely inkjet and aerosol jet printing, to control thin film thickness is investigated. The correlation between film …

Computational Estimation Of The Pka's Of Purines And Related Compounds, Kara L. Geremia

Browse all Theses and Dissertations

The acid dissociation value pKa of a compound provides important information regarding the neutral and ionic forms of the compound present under different conditions. However, for many compounds experimental pKa values are not available, and for others the measured values are sometimes uncertain. Consequently, having a computational means for estimating pKa values can be of benefit for biochemical, pharmaceutical, polymer, and many other studies. Purines form a key group of bioactive compounds whose acid/base activities are of considerable interest. The purine class includes such diverse compounds as the nucleic acid bases adenine and guanine, the gout-related compound uric acid, the …

Near Single-Molecule Sers-Based Detection Using Ultrafiltered, Unfunctionalized Silver Nanoparticles, Joshua Dale Baker

Browse all Theses and Dissertations

Silver nanoparticles (AgNPs) are currently widely-used in consumer products, therapeutics, biomedical devices, and electronics. Yet, one application for which AgNPs have been used extensively is surface-enhanced Raman spectroscopy (SERS)-based sensing. However, AgNP size and aggregation state are known to greatly influence these applications. This works aimed 1) to synthesize a large volume of unfunctionalized, Creighton AgNPs, to characterize their chemical and physical properties, 2) then to size-select AgNPs of 1-50 nm and 50-100 nm in diameter and to concentrate them using a three-step, "green" tangential flow ultrafiltration (TFU) process. 3) Finally, to determine and compare the SERS-based sensing capabilities of …