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M. Tech. Chemical Engineering. / Discusses the application of nanotechnology process to offer wholesale benefits in water and wastewater treatment, extremely very few researches have been conducted in this field. Even with the few, studies have mainly focused on using single ion aqueous solution. Such approach is novel but the results may not give true picture of performance of nano-materials. It's known that water quality adversely affect sorption process. It's thus product to use real field water and wastewater to get valuable results. Presently, there is almost no information is open literature regarding the application of nano-scale adsorbents in treating real water and wastewater.

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published_or_final_version / abstract / Electrical and Electronic Engineering / Master / Master of Philosophy

published_or_final_version / abstract / Physics / Master / Master of Philosophy

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This thesis presents investigations into the design and synthesis of nanomaterials in supercritical carbon dioxide (sc-CO₂) as well as novel experimental design methodologies. First, the process-structure-property relationships are studied for the deposition of materials from organometallic precursors in sc-CO₂. The materials that were investigated in these studies were: (1) the semiconductor material copper zinc tin sulfide (Cu₂ZnSnS₄, or CZTS), which has application in solar energy capture; (2) zinc sulfide nanoparticles deposited onto carbon nanotubes, which have application in optoelectronics; and (3) silver nanoparticles deposited on silicon and glass wafer surfaces, which find application as biosensors via surface enhanced Raman spectroscopy. Next, two novel experimental design methodologies were implemented. The first is termed layers of experiment with adaptive combined design (LoE/ACD), which efficiently optimizes a process that is expensive and time consuming to study by zooming in on the process optimum through successive layers. The mean silver nanoparticle size was optimized as a function of temperature in the sc-CO₂ system using the LoE/ACD approach. The second experimental design methodology is called initial experimental design (IED). The IED methodology was developed to choose the first round of experiments for a system that is expensive to study (in terms of time and money), poorly understood, and possesses a related, non-identical system that is well-studied. The IED approach was used to optimize the mean iridium nanoparticle size as a function of temperature given expert opinion, prior data, and an engineering model for silver nanoparticles synthesized in sc-CO₂.

This thesis presents the development of novel methodologies in the template mediated chemical synthesis of lariat and branched nucleic acids. The synthetic branched DNA and RNA may be applicable as probes in the elucidation of the splicing mechanism or as potential therapeutic agents. Furthermore, this body of work describes the novel synthesis of Ru(II) branched DNA as building blocks in the supramolecular assembly of nano-motifs. In general, insight into the utilization of nucleic acids as biological molecules and as nanomaterials is presented at the interface of chemistry and biology. / Chapter 2 delineates the regioselective template directed synthesis of Y-RNA via chemical ligation at the branch point of a 5'-phosphate to a 2'-hydroxyl. The branched molecules resemble lariats as they possess the analogous branched architecture. The oligonucleotide components are synthesized from commercially available phosphoramidite building blocks through automated solid-phase synthesis. A unique template directed method in the synthesis of DNA and RNA lariats is proposed in Chapter 3. The regioselective chemical ligation affords wild-type DNA and RNA formed through assembly of a single oligonucleotide strand. A parallel DNA:RNA hybrid association was observed in the preorganized assembly and extensively characterized. Characterization of the Y-RNA and lariat nucleic acids were carried out through techniques such as thermal denaturation analysis, polyacrylamide gel electrophoresis, enzymatic degradation with the RNA lariat debranching enzyme, alkaline treatment as well as MALDI-TOF mass spectrometry. / The second part of the thesis exploits DNA as a nanomaterial in the convergent solid-phase synthesis of Ru(II)-DNA conjugates as branched building blocks in the assembly of nanostructures. Chapter 4 describes the synthesis of Ru branched DNA, utilizing cis-[(bpy)2Ru(imidazole) 2]2+ moiety as the vertex tethered to parallel DNA covalently through flexible hexamethylene linkers. Complete physical characterization and preliminary hybridization studies are conducted. The Ru-DNA conjugates presented were found to be unstable to the protocols required for synthesis of mixed sequence derivatives. The stability and scope of synthesis of these molecules are further discussed. / As an alternative, Ru-DNA branched complexes of mixed sequences, exhibiting greater stability, were synthesized. The transition metal building blocks of Chapter 5 employ a more rigid branch point, linking two parallel DNA strands through a one methylene spacer to the cis-[Ru(bpy)2 (4,4'-bis(hydroxymethyl)-2,2'-bipyridine)][PF6]2 vertex. Physical characterization and the intrinsic luminescent properties of the transition metal complex were confirmed in both the Ru-branched DNA and hybrized forms. A comparative study of the self-assembly behavior of the Ru-DNA conjugates to that of unmetallated branched DNA was also conducted. Interestingly, results indicate a metal-mediated assembly of almost exclusive formation of one discrete Ru-DNA dimeric cyclic nanostructure, where as unmetallated DNA building blocks produced an array of products. Complete confirmation of these products is presented through PAGE and enzymatic digestions. Finally the synthesis of novel Delta and Λ Ru-branched DNA diastereomers is presented as potential building blocks in the creation of chiral metallo-supramolecular constructs.

<p>The main aim of this study was to develop a novel strategy for harnessing the properties of electroconductive polymers in sensor technology by using polymeric nanostructured blends in the preparation of high performance sensor devices.</p>

Silver nanoparticles (AgNP), the most popular nano-compounds, possess unique chemical, physical and biological properties. Albizia adianthifolia (AA) – rich in saponins – is a plant of the Fabaceae family, found abundantly on the East coast of Africa. This plant is well known for its medicinal properties, and although the exact phytochemistry of AA is unknown, recent research suggests that AA can be used for the treatment of certain pathologies. The biological properties of a novel silver nanoparticle (AAAgNP) synthesised from an aqueous leaf extract of AA, were investigated on A549 lung carcinoma cells. Cell viability was determined by the 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Cellular oxidative status (lipid peroxidation and glutathione (GSH) levels) were determined by the TBARS and GSH-Glo™ Glutatione assays respectively. ATP concentration was measured using the CellTitre-Glo™ assay. Caspase-3/-7, -8 and -9 activities were determined by Caspase-Glo® assays. Flow cytometry was used to measure apoptosis, mitochondrial (mt) membrane depolarisation, expression of CD95 receptors and intracellular smac/DIABLO levels. DNA fragmentation was assessed with the comet assay. The expression of p53, bax, PARP-1 and smac/DIABLO was evaluated by western blotting. Quantitative polymerase chain reaction was used to determine mRNA levels of bax and p53. AAAgNP caused a dose-dependent decrease in cell viability with a significant increase in lipid peroxidation (5-fold vs. control; p=0.0098) and decreased intracellular GSH (p=0.1184). A significant 2.5-fold decrease in cellular ATP was observed upon AAAgNP exposure (p=0.0040) with a highly significant elevation in mt membrane depolarisation (3.3-fold vs. control; p<0.0001). Apoptosis was also significantly higher (1.5-fold) in AAAgNP treated cells (p<0.0001) with a significant decline in expression of CD95 receptors (p=0.0416). AAAgNP caused a significant 2.5-fold reduction in caspase-8 activity (p=0.0024) with contrasting increases in caspase-3/-7 (1.7-fold vs. control; p=0.0180) and -9 activity (1.4-fold vs. control; p=0.0117). Western blots showed increased expression of smac/DIABLO (4.1-fold) in treated cells (p=0.0033). Furthermore, AAAgNP significantly increased the expression of p53, bax cleaved PARP-1 (1.2-fold; p=0.0498, 1.6-fold; p=0.0083 and 1.1-fold; p=0.0359 respectively). The expression of mRNA for both p53 and bax was also elevated post AAAgNP treatment, with 6-fold (p=0.0036) and 5-fold (p=0.0080) changes respectively compared to untreated cells. Data suggests that AAAgNP induces cell death in the A549 lung cells via the mt-mediated intrinsic apoptotic program. Further investigations are required to assess the potential use of AAAgNP in cancer treatment. / Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2012.