High Pressure Liquid Chromatography (HPLC) is a well-known and widely used analytical technique which is prevalent throughout the pharmaceutical industry as a research tool. Despite its prominence HPLC possesses some disadvantages, most notably slow analysis time and large consumption of organic solvents. Ultra Pressure Liquid Chromatography (UPLC) is a relatively new technique which offers the same separation capabilities of HPLC with the added benefits of reduced run time and lower solvent consumption. One of the key developments which facilitate the new UPLC technology is sub 2-µm particles used as column packing material. These particles allow for higher operating pressures and increased flow rates while still providing strong separation. Although UPLC technology has been available since early 2000, few laboratories have embraced the new technology as an alternative to HPLC. Besides the resistance to investing in new capital, another major roadblock is converting existing HPLC methodology to UPLC without disruption. This research provides a framework for converting existing HPLC methods to UPLC. An existing HPLC method for analysis of Galantamine hydrobromide was converted to UPLC and validated according to ICH guidelines. A series of statistical evaluations on the validation data were performed to prove the equivalency between the original HPLC and the new UPLC method. This research presents this novel statistical strategy which can be applied to any two methodologies to determine parity. / Chemistry

The pharmaceutical industry is at a critical juncture. With little remnants of the “Golden Age of the Pharmaceuticals” and applied pressure from large companies experiencing a dissipation of proprietary compounds, trends indicate a transition from a decade of stagnant productivity to one in which high throughput screening technologies and computational chemistry have diversified the discovery of new chemical entities (NCE). Despite these advances, drug discovery has been challenged by chemical entities that present delivery limitations due to the properties of their molecular structure. A recent evaluation of development pipelines indicated that approximately 70% of drug candidates exhibit poor aqueous solubility; thereby, resulting in erratic dissolution and insufficient bioavailability. Due to intrinsic physical properties, these compounds are known by the biopharmaceutics classification system (BCS) as class II compounds and are amendable to solubility and bioavailability enhancement platforms. Approaches such as pH adjustment, micronization, nanosuspensions, co-solvent solubilization, cyclodextrin inclusion complexation, salt formation, emulsified drug formulations and amorphous solid dispersions (ASD) are commonly utilized to maximize bioavailability and enrich in vivo absorption by prolonging exposure to high concentrations of dissolved drug in the gastrointestinal tract (GIT). Single-phase amorphous systems, such as solid dispersions, have been the focal point of the aforementioned practices as a result of their ability to promote a state of drug supersaturation over an extended duration of time. Within the structure of this dissertation, the application of concentration enhancing polymers for bioavailability enhancement of low solubility compounds was evaluated using solvent and fusion-based solid dispersion technologies. Exploiting a variety of analytical methodologies and tools, formulations produced by spray drying and hot melt extrusion (HME) techniques were investigated for sufficient dissolution enhancement. Studies revealed the selected formulation approaches provided a viable platform for manufacturing solid dispersions by illustrating systems that offered rapid and prolonged periods of supersaturation. While of the applications of single-phase amorphous solid dispersions are continuously expanding, their dissolution behavior is not as well understood. The overarching objective of dissolution testing during formulation development is to achieve biological relevance and predict in vivo performance. Proper in vitro dissolution testing can convey the influence of key in vivo performance parameters and be implemented for assessment and comparison of ASD formulations. Studies suggest that existing research fails to accurately address the intricacies associated with the supersaturated state. Upon solvation and during transit in the GIT, several high-energy drug-containing species are present in addition to free drug. Although these species are not absorbed in vivo, they play a pivotal role in generating and maintaining the supersaturation of a drug substance and function to replenish the supply of free drug as it permeates across the gastrointestinal membrane. Established dissolution apparatuses and methodologies in the United States Pharmacopeia (USP) focus on evaluation of total dissolved drug and may not be physiologically relevant for determining the amount of drug absorbed in vivo. Within the framework of this dissertation, a dissolution methodology was designed to reflect the physiochemical, physiological and hydrodynamic conditions that transpire throughout dissolution and absorption of an ASD during transit in the GIT. The apparatus and model present the ability to understand the kinetics and mechanisms of dissolution, supersaturation and nucleation. To support this hypothesis, analytical methods including high pressure liquid chromatography (HPLC) with ultraviolet (UV) detection were developed and fully validated. In parallel, a novel plasma membrane treatment was established to fabricate biomimetic membranes that possessed a hydrophilic and hydrophobic surface. The treated membranes are comprised of applied surface chemistries that emulate the unstirred aqueous layer created by microvilli protruding from the intestinal epithelial membrane as well as lipophilic constituents corresponding to the epithelial lipid membrane. Calculated in vitro similarity (f2) and difference (f1) factors support the hypotheses that plasma treated microporous polymer membranes exhibit biorelevant properties and demonstrate adequate biorelevance for in vitro dissolution studies. The described dissolution methodology has been applied as a tool for selection of candidates to move forward to pharmacokinetic studies. In a culminating study, in vitro – in vivo correlations (IVIVC) were performed employing the universal membrane-permeation non-sink dissolution method for formulations of Carbamazepine. To demonstrate the utility of the methodology, multiple level C correlations were established. The membrane-permeation model enables quantitative assessment of drug dissolution and absorption and offers a means to predict the relative in vivo performance of amorphous solid dispersions for BCS class II drug substances. / Chemistry

This dissertation elucidates the instrumentation and application of a hybrid ambient ionization source, laser electrospray mass spectrometry (LEMS), for the direct analysis and molecular imaging of biological tissue without matrix deposition. In LEMS, laser pulses from a Ti:Sapphire laser amplifier (60 fs, 800 nm, and 1 mJ) interact with surface analytes and transfer them from the condensed phase into the gas phase without the requirement of either exogenous matrix or endogenous water in the sample. The laser vaporized analytes are captured and ionized by an electrospray source, and finally detected by a mass analyzer. It was found that a turn-key, robust femtosecond fiber laser with longer wavelength, longer duration, and lower pulse energy at 1042 nm, 425 fs, and 50 µJ, respectively, provided comparable results with the Ti:Sapphire laser. Vaporization of intact, dried or aqueous cytochrome c and lysozyme samples was demonstrated by the fiber laser. A charge states distribution at lower charge states indicating folded conformation of proteins and the hemoglobin α subunit-heme complex from whole blood was observed. Endogenous anthocyanins, sugars, and other metabolites were detected and revealed the anticipated metabolite profile for the flower petal and leaf samples by the fiber laser. Phospholipids, especially phosphatidylcholine, were identified from a fresh mouse brain section sample. These lipid features were suppressed in both the fiber laser and Ti:Sapphire LEMS measurement in the presence of optimal cutting temperature compounds which are commonly used in animal tissue cryosectioning. This dissertation also details the design of an automated mass spectrometry imaging source based on the Ti:Sapphire LEMS. The laser, translation stage, and mass analyzer are synchronized and controlled using a customized user interface to enable step-by-step scanning of the area of interest on a given tissue sample. The imaging source is coupled with a high resolution accurate mass quadrupole time-of-flight (QTOF) mass analyzer with tandem mass analysis capability. A lateral resolution of 60 µm was demonstrated on a patterned ink film by LEMS imaging. Plant metabolites including sugar and anthocyanins were directly imaged from a leaf sample. Small metabolites, lipids and proteins were simultaneously imaged from a single tissue section of a pig liver sample. Biomarkers of blood-brain barrier damage and traumatic brain injury (TBI) that occurred during the injury were detected and imaged from a TBI mouse brain. The loading values from principal component analysis (PCA) were shown to be useful for identification of features of interest from the large LEMS imaging dataset. / Chemistry

Extracellular matrix (ECM) is a key component and regulator of many biological tissues. Several cardiovascular pathologies are associated with significant changes in the composition of the matrix. Better understanding of these pathologies and the physiological phenomenon behind their development depends on reliable methods that can measure and characterize ECM content and structure. In this dissertation, infrared spectroscopic methodologies are developed to study the changes in extracellular matrix of cardiovascular tissue in two cardiovascular pathologies; myocardial infarction and abdominal aortic aneurysm. The specific aims of this dissertation were: 1. To develop a Fourier transform infrared imaging spectroscopy (FT-IRIS) methodology for creating distribution maps of collagen in remodeled cardiac tissue sections after myocardial infarction, and to quantitatively compare maps created by FT-IRIS with conventional staining techniques. 2. To develop an FT-IRIS method to assess elastin and collagen composition in the aortic wall. This will be accomplished using ex vivo animal aorta samples, where the primary ECM components of the wall will be systematically enzymatically degraded. 3. To apply the newly developed FTIR imaging methodology to evaluate changes in the primary ECM components (collagen and elastin) in the wall of human AAA tissues. The infrared absorbance band centered at 1338 cm-1, was used to map collagen deposition across heart tissue sections of a rat model of myocardial infarction, and was correlated strongly in the size of the scar (R=0.93) and local intensity of collagen deposition (R=0.86). In enzymatically degraded pig aorta samples, as a model of ECM degradation in abdominal aortic aneurysm (AAA), partial least squares (PLS) models were created to predict collagen and elastin content in aorta based on collected FTIR spectra and biochemically measured values. PLS models based on FT-IRIS spectra were able to predict elastin and collagen content of the samples with strong correlations (R2=0.90 and 0.70 respectively). Elastin content prediction from IFOP spectra was successful through a PLS regression model with high correlation (R2=0.81). The PLS regression coefficient from the FT-IRIS models were used to map collagen and elastin human AAA biopsy tissue sections, creating a similar map of each component compared to histologically stained images. The mean value of collagen deposition in each tissue was calculated for 13 pairs of AAA samples where stress had been calculated using finite element modeling. In most pairs with stress values higher than 5 N/m2, collagen content was lower in the sample with higher stress value. Collagen maturity had a weak negative correlation (R=-0.35) with collagen content in these samples. These results confirm that infrared spectroscopy is a powerful tool that can be applied to replace or complement conventional methods such as histology and biochemical analysis to characterize ECM components in cardiovascular tissues. Furthermore, infrared spectroscopy has the potential for translation to a clinical environment to examine ECM changes in aorta in a minimally invasive fashion using fiber optic technology. / Mechanical Engineering

The electrocatalytic nitrogen reduction reaction (NRR) is of considerable interest due to its potential for less energy intensive and environmentally friendly ammonia production which is critical for agricultural and clean energy applications. However, the selectivity of NRR compared to the hydrogen evolution reaction (HER) often poses challenges for various catalysts, including Earth-abundant transition metal oxynitrides like Ti, V, and Co. In this work, a comparative analysis of the selectivity of these three metal oxynitrides was conducted, each having different metal oxophilicities. A combination of electrochemical, surface characterizations and density functional theory (DFT) calculations were employed to directly assess NRR and HER activities under the same reaction conditions. Results show that cobalt oxynitrides exhibit NRR activity at pH 10, involving the electrochemical reduction of both lattice-bound nitrogen and dissolved N2, although more HER activity was observed. In contrast, vanadium oxynitride films displayed HER inactivity at pH 7 and 10 but demonstrated NRR activity at pH 7, while titanium oxynitrides were active at pH 3.2 but inactive under neutral and basic pH conditions. These comprehensive studies highlight substantial variations in HER and NRR selectivity based on transition metal oxophilicity/azaphilicity, indicating distinct mechanisms governing NRR and HER mechanisms.

Six peripherally meso-modified Zn (II) porphyrin sensitizer dyes are designed and their J-V performance in dye sensitized solar cell (DSSC) evaluated. Electron-donating groups including phenothiazine, carbazole and pyrene are used to modify the porphyrin macrocycle at the meso-carbon position(s). To compare the effect of donor substitution on the performance of the cells in terms of short circuit current (Jsc), light harvesting efficiency (LHE) and power conversion efficiency (η), two sets of sensitizers with different degrees of substitution are synthesized. One set of dyes (mono-substituted) have one electron donor at trans-position to the acceptor, while the second set (tri-substituted) dyes have three of the same type electron donor groups at 5, 10 and 15 meso-carbon positions making all the six dyes push-pull type sensitizers incorporating 4'-carboxyphenyl as an electron-acceptor/anchor group. Different spectroscopic and electrochemical methods are used to study the photophysical and electrochemical properties of the dyes, while the photovoltaic performance of their cells under 1.5 A.M is studied using solar simulator. Meso-substitution of Zinc (II) porphyrin with these small donor molecules is shown to improve the light harvesting character of the Zinc (II) porphyrin macrocycle in the UV-Vis absorption while at same time improving its fluorescence quantum yield, excited-state life time and electron donating potential. All these factors combined make these meso-modified dyes better sensitizers with suitable Δ0 Δ0, and much improved power conversion efficiencies (PCE) compared to unsubstituted Zn (II) porphyrin. In particular, as a result of the peripheral modification, a doubling in efficiency in the mono- substituted series (RA-200-Zn; η=^M 4.2%, Jsc= -13.13 mA cm-2, Voc=0.54 ) and tripling in the tri-substituted series ( tri-phenothiazine Zn (II) Porphyrin; η= 7.3%, Jsc= -18.15 mA cm-2, Voc= 0.55 ) compared to unsubstituted Zn (II) porphyrin (η= 2.11%, Jsc= -5.7 mA cm-2, Voc= 0.53 V) has been accomplished.

The Abraham solvation model (ABSM) is an experimentally derived predictive model used to help predict various solute properties. This work covers various uses for the ABSM including predicting molar enthalpies of vaporization, predicting solvent coefficients for two new solvents (2,2,5,5-tetramethyloxolane and diethyl carbonate), predicting values for multiple new ionic liquids (ILs). This work also introduces a novel method for updating IL ABSM parameters by updating cation- and anion-specific values using linear algebra and binary matrices.

Ultrafast charge and electron transfer, primary events in artificial photosynthesis, are key in solar energy harvesting. This dissertation provides insight into photo-induced charge and electron transfer in the donor and acceptor constructs built using a range of donor and acceptor entities, including transition metal dichalcogenides (TMDs, molybdenum disulfide (MoS2), and tungsten disulfide (WS2)), N-doped graphene, diketopyrrolopyrrol (DPP), boron-dipyrromethene (BODIPY), benzothiadiazole (BTD), free base and metal porphyrins, zinc phthalocyanine (ZnPc), phenothiazine (PTZ), triphenylamine (TPA), ferrocene (Fc), fullerene (C60), tetracyanobutadiene (TCBD), and dicyanoquinodimethane (DCNQ). The carefully built geometries and configurations of the donor and (D), acceptor (A), with a spacer in these constructs promote intramolecular charge transfer, and intervalence charge transfer to enhance charge and electron transfer efficiencies. Steady-state UV-visible absorption spectroscopy, fluorescence and phosphorescence spectroscopies, electrochemistry (cyclic voltammetry (CV) and differential pulse voltammetry (DPV)), spectroelectrochemistry (absorption spectroscopy under controlled potential electrolysis), transient absorption spectroscopy, and quantum mechanical calculations (density functional theory, DFT) are used to probe ground and the excited state events as well as excited state charge separation resulting in cation and anion species. The current findings are useful for the increased reliance on renewable energy resources, especially solar energy.

Transition metal carbides (TMCs) are of increasing interest for catalytic processes. Their performance and stability under common oxidative conditions in catalytic reactions are crucial for several applications, including catalysis and electrochemical reactions. In this work, we report a detailed XPS study of the interactions of stoichiometric NbC and TaC surfaces with common oxidizing agents like O2 and H2O, which are important media in many chemical processes. Experimental results showed that NbC reacts with O2 to produce Nb sub-oxrides, while TaC is inert to O2 exposure. TaC surfaces are more sensitive to H2O vapor, with a greater surface oxidation and hydroxylation. Atmospheric oxidation of NbC and TaC was also studied, and results showed that both films oxidized yielding to the formation of Nb2O5 and Ta2O5, hydroxylated/ oxide carbon species, and some adventurous carbon build-up. TMCs are catalytically active in many reactions, especially those involving electrochemical nitrogen reduction reactions (NRR) to ammonia. Experimental and DFT calculations were used to provide insight on how carbide surface structures change electrochemically and how that evolution relates to NRR activity. Results showed that NbC has NRR activity at pH 3.2 after immersion in 0.3 M NaOH, leaving niobium suboxides. However, photoemission data showed that the Nb2O5 overlayer is restored after polarization to -1.3 V vs. Ag/AgCl, inhibiting NRR activity. TaC, on the other hand, is inactive for NRR at potentials more positive than -1.0 V, as NaOH treatment fails to remove the Ta2O5 surface layer induced by ambient exposure. The study also found that the formation and stabilization of intermediate oxidation states on the surface of transition metal ions are crucial for N≡N bond activation and NRR activity.

Doctor of Philosophy / Department of Chemical Engineering / Keith L. Hohn / To characterize surface properties by current techniques, metal oxides typically have to be pre-treated at high temperature to remove surface absorbents. Therefore, a new low temperature method which can provide information on the surface chemistry is desired. In this work, the surface properties of metal oxide samples were studied by tetrakis(dimethylamino)ethylene (TDE) chemiluminescence (CL). This chemiluminescent method was also employed in probing the properties of reversed microemulsions. It was found that the emission intensity vs. reaction time curve (I[subscript]t) of catalyzed TDE CL on MgO was affected by the distributions and types of surface hydroxyl groups. Isolated hydroxyls with lower coordination were found to have higher catalytic reactivity for the emission of TDE CL. Although hydrogen bonded hydroxyls also catalyze the TDE oxidation reaction, the influence on the light emission was negative. Because the properties of surface hydroxyls are associated with specific orientations of adjacent ions, information on surface hydroxyls can provide information about some general surface characteristics of a metal oxide. When characterizing surface hydroxyls on Al[subscript]2O[subscript]3 by TDE CL, it was found that the catalytic reactivity of isolated hydroxyl groups is strongly associated with the stretching frequency of isolated hydroxyl. The stretching frequency of an isolated hydroxyl group is related to the modification of the adjacent ions and the coordination of the isolated hydroxyl. The results showed that the blue-shifts in the stretching frequencies of isolated hydroxyls led to increases in the catalytic reactivity of Al[subscript]2O[subscript]3 surfaces for the emission of TDE CL. TDE CL was further applied in characterizing the surfaces of other metal oxides and chemically grafted Al[subscript]2O[subscript]3. The results indicated that the isolated hydroxyl groups with fewer adjacent ions likely have higher affinity for the binding of grafting agents. Higher emission intensities were obtained from catalyzed TDE CL on metal oxides featuring higher percentages of isolated hydroxyls. The determination of a surfactant’s critical micellar concentration was accomplished by measuring the decay rate of the emission of TDE CL in a reversed microemulsion system. In this study, the CMC values of non-ionic and ionic surfactants were measured in different non-polar solvents.