A Dissertation Submitted to the Faculty of Health Sciences, University of the Witwatersrand, in the Fulfilment of the Requirements for the Degree for Master of Science in Medicine (Pharmaceutics) Department of Pharmacy and Pharmacology, University of the Witwatersrand, Johannesburg, 2016 / MT2016

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Orientador: Nelson E. Duran Caballero / Tese (doutorado) - Universidade Estadual de Campinas. Instituto de Quimica / Made available in DSpace on 2018-08-05T05:07:17Z (GMT). No. of bitstreams: 1 Azevedo_MarceloMantovaniMartiniano_D.pdf: 5866189 bytes, checksum: 0aa431a83a079eb97dbe140e5e49ca79 (MD5) Previous issue date: 2005 / Resumo: Neste trabalho investigamos sistemas poliméricos transportando a violaceína, composto de interesse farmacológico, mais especificamente antitumoral, obtido a partir da biossíntese da Chromobacterium violaceum. Entretanto, trata-se de um composto insolúvel em meio aquoso e como conseqüência apresenta toxicidade e baixa biodisponibilidade, justificando seu encapsulamento. As microesferas (PCL) foram preparadas segundo princípios conhecidos de obtenção e estabilização de sistemas coloidais, pelo método de emulsão e evaporação de solvente e as nanoesferas (PLGA) foram obtidas pelo método de "nanoprecipitação" (separação de fases). Os sistemas foram caracterizadas quanto às propriedades físico-químicas por microscopias ótica, eletrônica de varredura, eletrônica de transmissão, fluorescência, varredura a laser confocal e distribuição de tamanho, potencial zeta e tensão interfacial. As nanoesferas contendo violaceína promoveram citotoxicidade, diferenciação celular e apoptose em linhagem leucêmica promielocítica humana HL60 e fibroblastos V-79. A violaceína está incorporada duas formas: isolada e auto-associada, distribuída por toda a partícula e fluoresce apenas em solução diluída e quando dispersa na matriz polimérica. O sistema nanoparticulado é citotóxico para HL60, induz apoptose (constatado nas medidas de potencial transmembrana) e diferenciação celular. A inibição do intumescimento mitocondrial evidenciou um efeito selante conferido pelo Pluronic à membrana de mitocôndrias, sugerindo um direcionamento a um alvo específico da célula. / Abstract: In this work we investigate polymeric systems transporting violacein, substance of pharmacological interest, more specifically antitumoral, obtained from the biosynthesis of Chromobacterium violaceum. However, violacein is an insoluble compound in water and as a consequence introduces toxicity and low bioavailability, justifying the entrappment. Microspheres (PCL) were obtained according to well-known principles of obtainment and stabilization of colloidal systems, by the solvent evaporation method and nanospheres (PLGA) were obtained by "nanoprecipitation method" (phase separation). These systems were characterized regarding the physical-chemistry properties by optical, fluorescence and laser confocal microscopies, scanning electronic microscopy, transmission electronic microscopy, diameter distribution, zeta potencial and interfacial tension. Violacein entrapped in nanospheres promoted citotoxicity, cellular differentiation and apoptosis in leukaemia promyelocytic human HL60 cell line and fibroblasts V-79. Violacein in PCL microspheres is present in two forms: isolated and auto-associated, distributed along the particle and there is emission in diluted solution and when dispersed in the polymeric matrix The nanoparticulated system is cytotoxic for HL60, induces apoptosis (verified by transmembrane potential measures) and induces cellular differentiation. Inhibition of the mitochondrial swelling occurrence is caused by Pluronic membrane sealing capability to mitochondrial membrane, suggesting the direction to a specific target of the cell. / Doutorado / Físico-Química / Doutor em Quimica

In this thesis, original theoretical and numerical investigations into the interaction of light with excitonic nanostructures are presented, in a bid to demonstrate that excitonic nanostructures are viable alternatives to the use of plasmonic nanostructures where electric field enhancement and confinement are sought. In particular, the field enhancement and confinement around excitonic nanostructures on resonance is shown to be comparable if not in excess of that around noble metal nanoparticles such as gold and silver. These excitonic modes, when set in the context of a core-shell geometry, are shown to offer tunability through nanoparticle design and through the index of the environment. In addition, hybrid `hyperbolic' and `plexcitonic' modes are shown to offer similar properties in metallic-excitonic nanostructures. Altogether, these excitonic and hybrid excitonic modes are shown to have potential in nanophotonic applications.

A multi-scale approach was used to investigate the occurrence and physical characteristics of viral surrogates in water systems. This approach resulted in a methodology to quantify the dynamics and physical parameters of viral surrogates, including bacteriophages and nanoparticles. Physical parameters impacting the occurrence and survival of viruses can be incorporated into models that predict the levels of viral contamination in specific types of water. Multiple full-scale water systems (U.S., Italy and Australia) were tested including surface water, drinking water, stormwater and wastewater systems. Water quality parameters assessed included viral markers (TTV, polyomavirus, microviridae and adenovirus), bacteriophages (MS2 and ΦX-174), and coliforms (total coliforms and E. coli). In this study, the lack of correlations between adenovirus and that of bacterial indicators suggests that these bacterial indicators are not suitable as indicators of viral contamination. In the wastewater samples, microviridae were correlated to the adenovirus, polyomavirus, and TTV. While TTV may have some qualities which are consistent with an indicator such as physical similarity to enteric viruses and occurrence in populations worldwide, the use of TTV as an indicator may be limited as a result of the detection occurrence. The limitations of TTV may impede further analysis and other makers such as coliphages, and microviridae may be easier to study in the near future. Batch scale adsorption tests were conducted. Protein-coated latex nanospheres were used to model bacteriophages (MS2 and ΦX-174) and includes a comparison of the zeta potentials in lab water, and two artificial groundwaters with monovalent and divalent electrolytes. This research shows that protein-coated particles have higher average log10 removals than uncoated particles. Although, the method of fluorescently labeling nanoparticles may not provide consistent data at the nanoscale. The results show both that research on viruses at any scale can be difficult and that new methodologies are needed to analyze virus characteristics in water systems. A new dynamic light scattering methodology, area recorded generalized optical scattering (ARGOS) method, was developed for observing the dynamics of nanoparticles, including bacteriophages MS2 and ΦX-174. This method should be further utilized to predict virus fate and transport in environmental systems and through treatment processes. While the concentration of MS2 is higher than ΦX-174 as demonstrated by relative total intensity, the RMSD shows that the dynamics are greater and have more variation in ΦX-174 than MS2 and this may be a result of the hydrophobic nature of ΦX-174. Relationships such as these should be further explored, and may reflect relationships such as particle bonds or hydrophobicity.

Noble metal nanomaterials have numerous uses in plasmonic and surface enhanced Raman scattering (SERS) detection applications; however, upon the addition of analytes, nanomaterials often undergo uncontrolled aggregation which leads to inconsistent signal intensities. To overcome this limitation, the effect of gold nanosphere concentration, column purification, and surface chemistry functionalization using internally etched silica stabilization methods was investigated on SERS assays for small molecule detection. Nanostructure composition, size, shape, stability, surface chemistry, optical properties, and SERS-activity were monitored using localized surface plasmon resonance (LSPR or extinction) spectroscopy, transmission electron microscopy (TEM), and Raman spectroscopy. First, the behavior of citrate-stabilized gold nanospheres was monitored as a function of molecular surface coverage. Both extinction and SERS spectral intensities increased linearly below monolayer functionalization. Above this value, however, uncontrolled nanoparticle aggregation occurred and large but irreproducible SERS signal intensities were monitored. Next, gold nanoparticles were encapsulated with varying silica shell thicknesses and purified using traditional centrifugation steps and/or column chromatography. Relative to the traditionally purified (i.e. centrifuged) samples, the SERS responses from small molecules using the column purified nanoparticle samples followed a well-known SERS distance-dependence model. Thus, surface chemistry cannot form more than a 2 nm thick layer on gold nanospheres if SERS applications were targeted. To overcome these challenges, gold nanospheres encapsulated with a thick silica shell were made SERS-active by etching the internal silica layer near the metal surface. During the synthesis of these internally etched silica-coated gold nanospheres, the LSPR wavelength shift, a parameter related to the effective local refractive index near the gold core, was monitored instead of etching time, in order to produce nanostructures with more uniform internal silica etching from sample to sample. The SERS-activity of a target molecule using these nanostructures was measured as a function of LSPR wavelength shift. SERS signal intensity increased, which suggested that more analyte molecules were able to bind to the gold surface because of the larger pore size in the silica layer near the metal core. Further exploration of these findings should increase the integration of solution-phase nanoparticles in more predictable functions in future applications, resulting in more quantitative and reproducible molecular detection in complex sample matrices, including biological and environmental samples.

This thesis reported synthesis of TiO2 nanostructures and Fe2O3 nanostructures and studied on self-assembling process. The morphologies, compositions, and physicochemical properties of the prepared samples were characterized by TEM, FESEM, XRD, FTIR, UV, and SQUID etc. Nanoparticles of transition metal oxides own their special function to become an interesting hot research topic in the recent decades. In particular, superparamagnetic iron oxide nanoparticles can be used as drug delivery agent and new hard disc drive materials. They have wide application in environment industry as well. Titanium dioxide nanoparticles can be applied in photocatalysts, UV protectors and dye sensitive solar cell etc. Their wide industrial applications for advanced technology development motivate scientists to develop simple, economical and novel synthetic methods, and explore their applications, so that the commercialization of the production of the nanomaterials becomes feasible. The objective of this project is to develop an effective, simple and economical technical route for synthesis of nanosized iron oxide and titanium oxide particles/rods/films. The approach and the progress are outlined as follows. Based on extensive literature reading on the project related area, a novel self-assembling technical route for iron oxide nanostructure and architecture was proposed which has been confirmed to be effective. Detailed experimental investigation on the synthesis of nanoparticles/rods, and instrumental characterization of the particle size, structure, and crystallites, etc. via TEM, FESEM, XRD, FTIR, UV, SQUID are conducted. Uniform nanorods of hematite iron oxide and titanium oxide nanospheres, and anatase TiO2 thin film with micropores have been successfully achieved. Some preliminary exploration for applications of the synthesized nanomaterials has also been carried out. Firstly, a novel assembled scheme of iron oxide nanostructure and architecture by selfassembling process was investigated. The sol-gel technical route was employed to synthesize nearly uniform nanorods of hematite particles. Morphologies and physicochemical properties of iron oxide nanostructure were characterized by analytical instrument. Secondly, titanium oxide nanospheres were synthesized via a hydrothermal process using titanium isopropoxide as the precursor. Titanium oxide nanospheres with inner nanospace andhighly organized crystallites in the shell structure and surface regions were synthesized. It demonstrated that the technical route developed in this work has a high versatility for structural engineering of various targeted morphological products. Thirdly, a simple process of preparing anatase TiO2 thin film with micropores was pursued. The synthesized nano thin film with micropores was used for the material of dye-sensitive solar cell; and effective electron transfer of titanium oxide electrode was confirmed by electrochemical voltammetry. Preparation of the titanium oxide electrode and its electrochemical analysis was studied. The application of the titanium oxide of microporous thin film material as a promoter for electrochemistry voltammetry measuring system was explored in this thesis. In conclusion, the iron oxide nanorods with superparamagnetic property were successfully synthesized by a simple method with low cost materials. Titanium oxide hollow nanospheres were achieved by the assistance of copolymer template. Titanium oxide thin film with microporous structure with significantly high efficiency in electron transfer was realized. Further researches on the synthesis of hybrid iron oxide and titanium oxide nanoparticles, their crystal growth architecture and mechanism, as well as exploration of their applications are recommended.

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