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Environmental and energy issues have stimulated renewed interest in utilizing both water and methanol as reagents and reaction mediums. Our current interest is to evaluate the scope of group nine organometallics and establish thermodynamic parameters for their reactivity in aqueous solvent. A comprehensive thermodynamic database for a wide scope of organo-rhodium transformations in a range of reaction media including benzene, water, and methanol has been well established by our group. Aqueous solutions of rhodium porphyrin have been determined to manifest an exceptional range of substrate reactions with carbon monoxide, dihydrogen, olefins, methanol and aldehydes. This study will focus on expansion of the thermodynamic database to all the group nine metals, particularly the iridium porphyrin systems in both water and methanol. Substrate reactivity and development of new mechanistic strategies for the conversion of carbon monoxide, alkanes, and alkenes to organic oxygenates are central objectives. Water/Methanol soluble porphyrin iridium complexes including iridium tetrakis(p-sulfonatophenyl)porphyrin ((TSPP)Ir) and iridium tetrakis(3,5-sulfonatomesityl)porphyrin ((TMPS)Ir) derivatives can be prepared by sulfonation of tetra phenyl porphyrin (H2TPP) and tetra mesityl porphyrin (H2TMP). The reactivity of dihydrogen with aqueous solutions of iridium(III) tetrakis(p-sulfonatophenyl)porphyrin ((TSPP)Ir(III)) complexes produce equilibrium distributions between six iridium species including iridium hydride ([(TSPP)Ir-D(D2O)]-4), iridium(I) ([(TSPP)IrI(D2O)]-5), and iridium (II) dimer ([(TSPP)IrII(D2O)]2-8) complexes. Each of these types of iridium porphyrin species including Ir(I), Ir(II), Ir(III), Ir-H, and Ir-OH function as precursors for a range of organometallic substrate reactions. A primary objective is to define the quantitative relationships pertaining to the distribution of species in aqueous solution as a function of the dihydrogen and hydrogen ion concentrations through direct measurement of five equilibrium constants along with free energy changes of coordinated water and free energy changes of reactions of dihydrogen in water. Reactivity, kinetics and evaluation of equilibrium thermodynamics, including the reactions of iridium hydroxide and methoxide with olefins to produce beta-hydroxyalkyl and beta-methoxyalkyl complexes, reactions of iridium hydride and olefins to produce iridium alkyl complexes, and reactions of iridium hydride with carbon monoxide to produce iridium formyl [Ir-CHO] complexes are also objectives of this research. Another research goal is the design and synthesis of diporphyrin ligands that form dimetal complexes capable of preorganizing transition states for substrate reactions that involve two metal centers. Dirhodium dimetalloradical complexes are observed to manifest large rate increases over mono-metalloradical activation reactions of hydrogen, methane, and other small molecule substrates. In this study, synthesis of diporphyrin (bisporphyrin) ligands and other ligands which will permit dimetallo complexes like anti-aromatic [14]annulene and low steric porphine ligands will be also be examined. / Chemistry

The commonly used PLGA-based delivery systems are often limited by their inadequate drug loading and release properties. This study reports the integration of oil into PLGA to form the prototype of a hybrid drug carrier PONC. Our primary goal is to confer the key strength of lipid-based drug carriers, i.e. efficient encapsulation of lipophilic compounds, to a PLGA system without taking away its various useful qualities. The PONC were formulated by emulsification solvent evaporation technique, which were then characterized for particle size, encapsulation efficiency, drug release and anticancer efficacy. The ATRA loaded PONC showed excellent encapsulation efficiency and release kinetics. Even after surface functionalization with PEG , controlled drug release kinetics was maintained, with 88.5% of the encapsulated ATRA released from the PEG-PONC in a uniform manner over 120 hours. It also showed favorable physicochemical properties and serum stability. PEG-PONC has demonstrated substantially superior activity over the free ATRA in ovarian cancer cells that are non-responsive to the standard chemotherapy. The newly developed PEG-PONC significantly reduced the IC50 values (p<0.05) in the chemoresistant cells in both MTT and colony formation assays. Hence, this new ATRA-nanoformulation may offer promising means for the delivery of lipophilic compounds like all-trans retinoic acid to treat highly resistant ovarian cancer. / Pharmaceutical Sciences

<p> Affinity capillary electrophoresis (ACE) is a versatile technique for assessing non-covalent molecular interactions in free solution provided that there are significant changes in apparent analyte mobility as a result of specific complexation. The thermodynamics of receptor binding are vital for controlling the selectivity in molecular recognition, which are dependent on the electrolyte composition of solution. In addition, the conformational properties of the complex (e.g., size, shape) can also contribute a secondary influence on receptor selectivity that has been relatively unexplored in ACE to date. In this study, dynamic 1:1 host-guest inclusion complexation involving a anionic resorcin[4]arene with a group of neutral corticosteroids was examined by ACE, where the macrocycle serves as both an intrinsic buffer and electrokinetic host. The tetraethylsulphonate derivative of 2-methylresorcin[4]arene (TESMR) was first synthesized via an acid-catalyzed condensation reaction, which was then fully characterized in terms of its weak acidity (pKa), mobility, UV spectral and buffer capacity properties. TESMR solutions were demonstrated to have stable intrinsic buffer and ion transport properties at pH 7.5 even at low ionic strength. It was determined that over a 200 % enhancement in the apparent binding constant (KB) was realized by ACE when using TESMR as an intrinsic buffer at pH 7.5 relative to an extrinsic sodium phosphate buffer system, which was also confirmed by 1H-NMR. The coupling of thermodynamic (KB) and electrokinetic (μep, AC) factors associated with complex formation in buffered aqueous solutions that minimize the effects of extrinsic electrolytes serves to enhance enthalpy-driven molecular recognition processes by ACE.</p> / Thesis / Master of Science (MSc)

Solutions of poly(2-ethyl-2-oxazoline) and poly(2-methyl-2-oxazoline) in water and several alcohols were characterized by light scattering and cloud point measurements. The second virial coefficients in water were found to decrease with increasing temperature, reflecting lower critical solution behavior, which is consistent with the cloud point measurements. The temperature dependence of the second virial coefficients revealed that specific interactions between polymer and water dominated the free energy of mixing. The Flory-Huggins x parameter determined from light scattering was in the range 0.48 - 0.49 in water and 0.32 - 0.41 in ethanol. The Kuhn length for PEOX was determined to be 0.77 nm which corresponds to less than two monomer units, indicating relatively flexible chains of PEOX. The segmental adsorption energy, x_s^po, of PEOX was measured using a desorption/displacement technique. PEOX was desorbed from silica with five low molecular weight organic displacers in two solvents - water and ethanol - to obtain values of the critical volume fraction of the displacer at which desorption was complete, Φ_cr. The high adsorption energy parameters are consistent with the polymer adsorbing principally by hydrogen bonding between the carbonyl groups on the polymer and surface silanol groups. The difference in adsorption energies in water and ethanol reflect specific solvent effects that may be related to the formation of hydrogen bond bridges between PEOX and silanol groups in water. Adsorption of PEOX from water, alcohols and chlorobenzene onto silica was investigated by measuring PEOX adsorption isotherms using a depletion method. A linear relationship of the plateau adsorption amount, Γ_p vs. log (molecular weight) was obtained, which agreed qualitatively with the Scheutjens-Fleer (S-F) mean field adsorption theory. The values of Γ_p, varied significantly with solvent type as well as with pH and electrolyte concentration in water. These variations in Γ_p, were due to changes of the polymer solvency and the silanol density on the silica particles. Competitive adsorption experiments of PEOX with various polymers were performed, including poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO) poly(vinyl methyl ether) (PVME), and poly(dimethyl siloxane) (PDMS). PEOX showed a higher affinity to the silica surface than other polymers. This suggested that PEOX had good potential for serving as an anchor block for diblock copolymer stabilizers for metal oxides in water. The solubility of homopolymers PEOX, PEO, PPO, PVME, and PDMS and copolymers PEOX-PDMS and PEOX-PVME was investigated in water, alcohols, and chlorobenzene using static light scattering (SLS). The steric stabilization effect of silica dispersions in chlorobenzene by PEOX-PDMS was measured by dynamic light scattering (DLS). The stability was qualitatively related to the average particle hydrodynamic diameter against time. The adsorbed amount and layer thickness of diblock copolymer poly(dimethyl amino ethyl methacrylate-b-n-butyl methacrylate) (DMAEM-BMA) on silica surfaces from isopropanol was measured. The linear dependence of the adsorbed amount and thickness with respect to the tail block length was obtained. This is consistent with the Marques-Joanny model. / Ph. D.

Curdlan, a (1,3)-linked linear homopolysaccharide composed of beta-D-glucan, is produced by the bacterium Alcaligenes faecalis var. myxogenes. Several strategies to synthesize chemically modified curdlan derivatives have been reported, but there have been few reports of regioselective functionalization at specific positions of the curdlan backbone, especially of aminated curdlan derivatives which have remarkable potential in biomedical and pharmaceutical applications. We demonstrate herein the design, synthesis and characterization of a family of regioselectively aminated curdlan derivatives including 6-deoxy-6-(bromo/azido/amino/amido/ammonium) curdlans starting from 6-bromo/azido-6-deoxycurdlan. A key reaction that enabled the whole synthesis of new curdlan derivatives at C-6 described in this dissertation was the highly selective bromination of curdlan. The resultant 6-bromo-6-deoxycurdlan, prepared with high regioselectivity, was treated with trialkylamines or heterocyclic amines to produce a range of water-soluble curdlan ammonium salts. The bromide was then nucleophilically displaced by sodium azide to produce the versatile precursor 6-azido-6-deoxycurdlan. Its water solubility was enhanced either by the incorporation of hydrophilic trioxadecanoate esters into O-2/4 positions or by the borohydride reduction to afford 6-amino-6-deoxycurdlan. The iminophosphorane intermediate generated during Staudinger reactions was further investigated for subsequent syntheses: i) 6-amino or 6-amido-6-deoxycurdlan by in situ reaction with water or excess carboxylic anhydride, ii) 6-monoalkylamino curdlan by reductive amination using aldehydes and sodium cyanoborohydride, and iii) 6-dialkylamino-/tri-alkylammoniocurdlans by reacting with methyl iodide. Such derivatives could have properties useful for a range of biomedical applications, including interactions with proteins, encapsulation of drugs, and formulation with genes or other biological compounds. / Ph. D.

No / The formulation of poorly water-soluble drugs is a challenging problem within pharmaceutical development. Recently, formulation using nanoparticles was highlighted as showing great potential to improve the dissolution and solubility characteristics of poorly water soluble drugs.

Introduction: Integrating 3-dimensional (3D) printing with lipid-based formulation (LBF) is impacting pediatric pharmaceutical manufacturing by enabling personalized oral dosage forms tailored to children's specific needs. Serious challenges are created by manipulating conventional adult dosages to produce suitable dosages for the pediatric population. The study explores an emulsion gel with two model lipophilic drugs, Aprepitant and Irbesartan, using semi-solid extrusion (SSE) as a 3D printing method to produce patient-centered dosages. Method: The solubility of the two model drugs in the studied LBF type IIIA – MC was determined using the shake-flask method combined with High-Performance Liquid Chromatography with Ultraviolet Detection (HPLC-UV) analysis. Once determined, LBF was loaded with 90% of the soluble drug amount to later produce the emulsion by mixing the drug-loaded LBF with Milli-Q water. The emulsion gel was produced as the next step by adding three different polymers to the emulsion. The three polymers were Methylcellulose Methocel (A4C), Methylcellulose Methocel (A4M), and Sodium Crosscarmellose (AcDiSol). Lastly, tablets were 3D-printed using a BIO X 3D printer with a pneumatic printhead. The tablets were vacuum-dried and analyzed for mass and content uniformity, and disintegration time.  Results: The thermodynamic solubility of Aprepitant in LBF IIIA – MC was determined to be 11.30 mg/g while the solubility of Irbesartan was 4.08 mg/g. The produced tablets contained lower concentrations of the drugs compared to the traditional dosages available on the market. The 3D-printed tablets passed the European Pharmacopeia requirements for mass and content uniformity, and disintegration time.  Conclusion: The study showed justified results indicating the emulsion gel can be used to produce tablets loaded with different poorly water-soluble drugs. All characterization studies done on the 3D-printed tablets carried out according to the European Pharmacopeia guidelines showed correct mass and content uniformity together with reasonable disintegration time. This suggests that the emulsion gel has the potential to be used to produce tablets loaded with any other lipophilic drug, potentially multiple drugs loaded at the same time.

A size-selected series of water-soluble luminescent Ag–In–S (AIS) and core/shell AIS/ZnS QDs were produced by a precipitation technique. Up to 10–11 fractions of size-selected AIS (AIS/ZnS) QDs emitting in a broad color range from deep-red to bluish-green were isolated with the photoluminescence (PL) quantum yield reaching 47% for intermediate fractions. The size of the isolated AIS (AIS/ZnS) QDs varied from ~2 nm to ~3.5 nm at a roughly constant chemical compo- sition of the particles throughout the fractions as shown by the X-ray photoelectron spectroscopy. The decrease of the mean AIS QD size in consecutive fractions was accompanied by an increase of the structural QD imperfection/disorder as deduced from a notable Urbach absorption “tail” below the fundamental absorption edge. The Urbach increased from 90–100 meV for the largest QDs up to 350 meV for the smallest QDs, indicating a broadening of the distribution of sub-bandgap states. Both the Urbach energy and the PL bandwidth of the size-selected AIS QDs increased with QD size reduction from 3–4 nm to ~2 nm and a distinct correlation was observed between these parameters. A study of size-selected AIS and AIS/ZnS QDs by UV photoelectron spectroscopy on Au and FTO substrates revealed their valence band level EVB at ~6.6 eV (on Au) and ~7 eV (on FTO) and pinned to the Fermi level of conductive substrates resulting in a masking of any possible size- dependence of the valence band edge position.

A size-selected series of water-soluble luminescent Ag–In–S (AIS) and core/shell AIS/ZnS QDs were produced by a precipitation technique. Up to 10–11 fractions of size-selected AIS (AIS/ZnS) QDs emitting in a broad color range from deep-red to bluish-green were isolated with the photoluminescence (PL) quantum yield reaching 47% for intermediate fractions. The size of the isolated AIS (AIS/ZnS) QDs varied from ~2 nm to ~3.5 nm at a roughly constant chemical compo- sition of the particles throughout the fractions as shown by the X-ray photoelectron spectroscopy. The decrease of the mean AIS QD size in consecutive fractions was accompanied by an increase of the structural QD imperfection/disorder as deduced from a notable Urbach absorption “tail” below the fundamental absorption edge. The Urbach increased from 90–100 meV for the largest QDs up to 350 meV for the smallest QDs, indicating a broadening of the distribution of sub-bandgap states. Both the Urbach energy and the PL bandwidth of the size-selected AIS QDs increased with QD size reduction from 3–4 nm to ~2 nm and a distinct correlation was observed between these parameters. A study of size-selected AIS and AIS/ZnS QDs by UV photoelectron spectroscopy on Au and FTO substrates revealed their valence band level EVB at ~6.6 eV (on Au) and ~7 eV (on FTO) and pinned to the Fermi level of conductive substrates resulting in a masking of any possible size- dependence of the valence band edge position.