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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Nanoporous Aluminum Oxide – A Promising Support for Modular Enzyme Reactors

Kjellander, Marcus January 2013 (has links)
Nanoporous alumina is a rather newly characterized material that so far has found limited use in the construction of bioreactors. The material has many advantages compared to conventional immobilization matrices. I have investigated its use in flow-through bioreactors. The rigidity and porous structure of the material makes it an excellent choice for multienzyme reactor construction. The total activity in a reactor is easily controlled by the number of membranes since the porosity makes the material less prone to increase flow system pressure. This bioreactor is suitable for characterization of new enzymes since the amount of immobilized enzyme is standardized and the enzyme may be reused many times. We designed a simple stepwise technique for covalent immobilization on this matrix in a monolayer to minimize mass transfer effects in the reactor function. The kinetic parameters for ten different substrates were investigated for immobilized alcohol oxidase and, as a second step, a two-step reactor was also designed by addition of horseradish peroxidase. This bienzymatic reactor was, in turn, employed for measuring injected alcohol concentrations. The use of the matrix for substrate specificity screening was proven for two new epsilon-class glutathione transferases from Drosophila melanogaster. Immobilized trypsin showed a substantially prolonged lifetime and its potential use as an on-line digestion unit for peptide mass fingerprinting was also demonstrated. Finally, I investigated the immobilization of the model enzyme lactate dehydrogenase by adsorption mediated by metal ion chelation similar to IMAC. Regeneration was here possible multiple times without loss of capacity. In conclusion, immobilization of enzymes on nanoporous alumina is a convenient way to characterize, stabilize and reuse enzymes.
22

Azo dye biodegradation and the effect of immobilization on pseudomonas sp.ADD16-2.

January 1997 (has links)
by Yung-Ho Chow. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 162-173). / ACKNOWLEDGEMENT --- p.i / ABSTRACT --- p.ii / LIST OF TABLES --- p.iii / LIST OF FIGURES --- p.iv / ABBREVIATION --- p.vi / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Azo dyes --- p.3 / Chapter 1.2 --- Chemistry of azo dyes --- p.3 / Chapter 1.2.1 --- Synthesis of azo dyes --- p.3 / Chapter 1.2.2 --- Oxidation and reduction --- p.4 / Chapter 1.2.3 --- Dyeing --- p.4 / Chapter 1.2.4 --- Staining to biological materials --- p.5 / Chapter 1.3 --- Toxicity of azo dyes --- p.5 / Chapter 1.3.1 --- Toxicity to mammals --- p.6 / Chapter 1.3.2 --- Toxicity to microorganisms --- p.6 / Chapter 1.4 --- Degradation of azo dyes --- p.9 / Chapter 1.4.1 --- Degradation of azo dyes by mammalian system --- p.9 / Chapter 1.4.2 --- Degradation of azo dyes by fungi system --- p.10 / Chapter 1.4.3 --- Degradation of azo dyes by bacteria --- p.11 / Chapter 1.4.3.1 --- Requirement of cofactors --- p.12 / Chapter 1.4.3.2 --- Effect of oxygen --- p.13 / Chapter 1.4.3.3 --- Effect of cell permeability --- p.14 / Chapter 1.4.3.4 --- Redox potential and rate of dye degradation --- p.15 / Chapter 1.4.3.5 --- Rate of dye degradation --- p.15 / Chapter 1.4.4 --- Azo-reductase --- p.18 / Chapter 1.4.4.1 --- Microsomal azo-reductase --- p.18 / Chapter 1.4.4.2 --- Bacterial azo-reductase --- p.19 / Chapter 1.5 --- Immobilization of microorganisms --- p.19 / Chapter 1.5.1 --- Gel matrix for entrapment --- p.20 / Chapter 1.5.2 --- Effect of gel entrapment to microbial cells --- p.21 / Chapter 1.5.2.1 --- Reduced diffusion of substrates in gel --- p.22 / Chapter 1.5.2.2 --- Effects in growth patterns --- p.22 / Chapter 1.5.2.3 --- Protection of entrapped microbial cells --- p.23 / Chapter 1.5.2.4 --- Increase metabolic activities --- p.26 / Chapter 1.5.2.5 --- Reduction of water activity --- p.27 / Chapter 1.5.2.6 --- Prolongation of products formation --- p.27 / Chapter 1.6 --- Application of immobilized microorganisms in bio-remediation of azo dyes --- p.28 / Chapter 1.7 --- Purpose of study --- p.28 / Chapter CHAPTER 2 --- MATERIALS AND METHODS --- p.29 / Chapter 2.1 --- Materials --- p.31 / Chapter 2.1.1 --- Chemicals --- p.31 / Chapter 2.1.2 --- Bacteria --- p.36 / Chapter 2.1.3 --- Instruments --- p.36 / Chapter 2.1.4 --- Media --- p.37 / Chapter 2.1.4.1 --- Luria Broth medium --- p.37 / Chapter 2.1.4.2 --- Minimal medium --- p.37 / Chapter 2.2 --- Methods --- p.38 / Chapter 2.2.1 --- Culture of Pseudomonas sp. ADD16-2 --- p.38 / Chapter 2.2.2 --- Purification and characterization of azo-reductase --- p.38 / Chapter 2.2.2.1 --- Preparation of crude extract --- p.38 / Chapter 2.2.2.2 --- Purification of azo-reductase --- p.39 / Chapter 2.2.2.2a --- Preparation of SDS-polyacrylamide gel --- p.40 / Chapter 2.2.2.2b --- Sample preparation and application --- p.41 / Chapter 2.2.2.2c --- Electrophoresis condition --- p.41 / Chapter 2.2.2.2d --- Staining of gel by Commasie blue --- p.41 / Chapter 2.2.2.3 --- Measurement of azo-reductase activity --- p.41 / Chapter 2.2.2.4 --- Determination of effect of pH to azo- reductase activity --- p.42 / Chapter 2.2.3 --- Measurement of azo dye decolourization rate by whole cells of Pseudomonas sp. ADD16-2 --- p.42 / Chapter 2.2.3.1 --- Preparation of cells --- p.42 / Chapter 2.2.3.2 --- Measurement of azo dye decolourization rate --- p.43 / Chapter 2.2.4 --- Measurement of azo dye decolourization rate by crude extract of Pseudomonas sp. ADD16-2 --- p.43 / Chapter 2.2.5 --- Determination of dye degradation products by High Performance Liquid Chromatography (HPLC) --- p.46 / Chapter 2.2.6 --- Measurement of redox potential of azo dyes --- p.47 / Chapter 2.2.7 --- Determination of the effect of cell permeation agents on dye degradation --- p.48 / Chapter 2.2.8 --- Determination of cell permeability --- p.48 / Chapter 2.2.9 --- To study the effect of the presence of dye degradation products or added aromatic amines to dye degradation --- p.49 / Chapter 2.2.9.1 --- Whole cell reactions --- p.50 / Chapter 2.2.9.2 --- Crude extract or purified azo-reductase reaction --- p.50 / Chapter 2.2.10 --- Immobilization of cells by different matrix --- p.50 / Chapter 2.2.10.1 --- Preparation of cells for immobilization --- p.50 / Chapter 2.2.10.2 --- Immobilization by calcium alginate --- p.51 / Chapter 2.2.10.3 --- Immobilization by K-carrageenan --- p.51 / Chapter 2.2.10.4 --- Immobilization by polyacrylamide gel --- p.52 / Chapter 2.2.10.5 --- Immobilization by agarose gel --- p.52 / Chapter 2.2.10.6 --- Measurement of viability of immobilized cells --- p.53 / Chapter 2.2.10.7 --- Measurement of azo dye degradation rate in immobilized cell system --- p.53 / Chapter 2.2.10.8 --- Measurement of intracellular K in calcium alginate immobilized cells --- p.53 / Chapter 2.2.10.9 --- Long term batch culture of immobilized cells --- p.53 / Chapter 2.2.11 --- Determination of toxicities of azo dyes and aromatic amines --- p.54 / Chapter CHAPTER 3 --- RESULTS --- p.55 / Chapter 3.1 --- Purification of azo-reductase 、 --- p.56 / Chapter 3.2 --- Properties of azo-reductase --- p.63 / Chapter 3.3 --- Degradation of azo dyes --- p.73 / Chapter 3.3.1 --- Degradation profiles --- p.73 / Chapter 3.3.2 --- Products of dye degradation --- p.80 / Chapter 3.3.3 --- Effect of cell permeability on dye degradation rate --- p.94 / Chapter 3.3.4 --- Induction of dye degradation rate by prior dye degradation exercise or by direct addition of aromatic amines --- p.97 / Chapter 3.4 --- Effect of immobilization --- p.114 / Chapter 3.4.1 --- Effect of different immobilization matrix --- p.114 / Chapter 3.4.2 --- Toxicities of different azo dyes and aromatic amines to free and immobilized cells --- p.124 / Chapter 3.4.3 --- Effect of azo dyes and aromatic amines at high concentrations on free and on immobilized cells --- p.124 / Chapter CHAPTER 4 --- DISCUSSION --- p.145 / Chapter 4.1 --- Degradation of azo dyes by Pseudomonas sp. ADD16-2 --- p.146 / Chapter 4.2 --- Permeability of azo dyes in Pseudomonas sp. ADD 16-2 --- p.150 / Chapter 4.3 --- Induction of dye degradation rate --- p.155 / Chapter 4.4 --- Effect of immobilization --- p.159 / CONCLUSION --- p.161 / REFERENCE --- p.162 / APPENDIX --- p.174 / appendix 1 Structures of azo dyes that have similar structures to Orange G --- p.175 / appendix 2 Absorption profiles of azo dye degradation products taken at different time intervals --- p.178 / appendix 3 Effect of pre-incubation time to dye degradation rate of Orange I by Pseudomonas sp. ADD16-2 --- p.183 / appendix 4 Effect of calcium ions (0-0.2 M) to (A) dye degradation and (B) viability of cells --- p.185 / appendix 5 Effect of ATP on induction effect of Orange I on whole cells of Pseudomonas sp. ADD16-2 --- p.187 / appendix 6 Summary of azo dyes that were degraded by Pseudomonas putida AD1 cells --- p.189
23

Pretreatment of wastewater containing fats and oils using an immobilized enzyme.

Jia, Huanfei January 2002 (has links)
This thesis investigates an application of immobilized lipase for pre-treating wastewater containing fats and oils, which is difficult to treat practically. The kinetics of soluble lipase was studied for establishing background of the lipase. The immobilization of lipase was adopted in order to repeatedly use the expensive lipase. The developed immobilization methods were based on the characteristics of carriers, but covalent bonding of lipase was preferred because of strong adsorption nature. Three types of materials, nylon membrane and polystyrene-divinylbenzene and silica gel beads, were used for studying the lipase immobilization characteristics. The lipase from Canada rugosa was chosen because of its relatively high catalytic activity and commercial availability. The oily wastewater sources used were a simulated mixture of olive oil and distilled water as well as actual restaurant oily wastewater. A packed bed reactor packed with immobilized lipase was suitable for the study. Moreover, a comparative study of anaerobic digestion of lipase treated and un-treated oily wastewater was undertaken to evaluate the efficiency of the lipase pre-treatment method due to lack of the relevant literature in the enzymatic wastewater treatment field. The kinetics of lipase catalyzed hydrolysis reactions was investigated in a stirred tank reactor. The experimental results confirmed that the lipase catalyzed reaction obeyed Michaelis-Menten model. The optimal pH and temperature of the lipase catalysed hydrolysis reaction were 7 and 37°C, respectively. The conversion of oil to fatty acid was dependent on the reaction time and mass of the enzyme used. The lipase activities depended on the concentrations of some selected additives. Calcium ion improved lipase activity significantly amongst the additives used. / The immobilization of lipase was carried out using different materials, nylon membranes, polystyrene-divinylbenzene beads, and silica gel. Covalent adsorption was simple and successful for immobilizing the lipase onto nylon membrane which was pre-treated with HC1 solution for releasing amino groups. The adsorption of lipase was completed after only a 2-hour reaction time. It was much more practical for this shorter adsorption time (2 hours) rather than the 24 hours required for physical capillary adsorption of lipase. The properties of the immobilized lipase and the performance of the reactors we compared amongst the soluble and immobilized lipase forms. The immobilization, particularly for covalent bonding, made lipase more resistant to thermal deactivation. It was evident that the optimum temperature was shifted from 37°C for the soluble lipase to 45 and 40°C for immobilized lipase adsorbed onto nylon and polystyrene-divinylbenzene beads, respectively. The immobilized lipase could be used repeatedly with only little activity loss. The repeatedly operational stability made the reuse of the immobilized lipase possible. Comparison was also made between two types of beads, polystyrene-divinylbenzene beads and silica gels. Though polystyrene-divinylbenzene beads showed higher lipase activity and shorter adsorption time when compared to silica gels, the forme beads were not suggested for large scale study because of high cost of the beads. On improvement achieved in this work was that the 24 hours required for silanization of silica gel was reduced to only a few hours using evaporating 3-APTES in acetone instead of refluxing 3-APTES in toluene. / It is worthwhile to point out that much higher enzyme activity was obtained using the packed bed reactor as against the membrane reactor when aqueous oil emulsion was fed into the reactors. The lipase activity was 64.2% of soluble lipase activity for the immobilized lipase in the packed reactor but its activity was hardly detectable in the membrane reactor. Moreover, the operation of the packed bed reactor solved the of separating problem that severely hampered the lipase catalytic activity in the membrane reactor in aqueous phase. This result suggests that the packed bed reacts with the immobilized lipase is applicable in treating oily wastewater. The intrinsic parameters, Vmax and Km, were evaluated to study the internal diffusional effects of the porous spherical silica gel on the immobilized lipase. The changes of Vmax and Km for the immobilized lipase from those of the soluble lipase indicated that some alteration in the lipase intrinsic properties was caused by the immobilization of lipase. However, the magnitude of Thiele modulus suggested the immobilized lipase was most likely reaction controlling. In addition, good agreement for Vmax and Km from experiments and numerical model estimations seemed to suggest that the numerical model could be used for estimating Vmax and Km for the immobilized lipase. / An application was tried for conducting the hydrolysis of oily restaurant wastewater by soluble and the immobilized lipase. Enzyme activity of both forms was severely inhibited by the oily wastewater. The enzymatic activity was only 20% and 15% for soluble and the immobilized lipase, respectively, when compared to the initial activity value for the hydrolysis of olive oil by soluble lipase. Evaluation of the efficiency for the proposed lipase pre-treatment method was carried out by monitoring the performance of two anaerobic digesters. These two digesters were fed with lipase treated and untreated restaurant wastewater that was neutralised with KOH solution prior to feeding. The oil-floating problem was minimised by this saponification of fatty acids with potassium hydroxide. However, there was no clear sign of an improvement for the treatment efficiency of the anaerobic digesters in terms of COD removal and methane production rate resulted in digesting lipase treated oily wastewater when compared to the one without lipase pre-treatment.
24

Tridentate Phosphine Linkers for Immobilized Catalysts: Development and Characterization of Immobilized Rhodium Complexes and Solid-State NMR Studies of Polymers

Guenther, Johannes 1983- 14 March 2013 (has links)
The major directions of this thesis involve (1) the synthesis, immobilization, and characterization of tridentate phosphine linkers on silica, (2) the study of unprecedented Si2C bond cleavage in Rh and Ir phosphine complexes, and (3) the study of performance polymers with solid2state NMR techniques. First a brief overview of solid2state NMR and its relevance to the various areas of chemistry covered in this thesis is given. Following the synthesis, immobilization, and characterization of tridentate phosphine ligands, EtOSi[(CH2)nPPh2]3 (n = 4, 7, 11) and [MeP((CH2)nPPh2)3]+I? (n = 4, 7, 11) on silica is detailed. Both, immobilization by electrostatic interactions and by a covalent siloxane bond to the support, is studied and compared. Ligand exchange with Wilkinson?s catalyst affords immobilized Rh complexes. These materials are applied to catalytic olefin hydrogenation. In either case active hydrogenation catalysts are obtained that can easily and efficiently be recycled up to 30 times. Detailed investigations reveal that irrespective of the linkage to the support the catalysts consist initially of well2defined molecular species that form supported Rh nanoparticles with a narrow size distribution in the course of the catalytic reaction. The nanoparticles are active hydrogenation catalysts as well, and no metal leaching into solution is detected. The reaction of the tridentate phosphine ligands EtOSi[(CH2)2PPh2]3 and MeSi[(CH2)2PPh2]3 with Rh and Ir complexes is investigated. This reaction does not lead to the anticipated Wilkinson2type complexes with the metal in the +I oxidation state, but instead to oxidative addition of the C(sp3)2Si bond to Rh or Ir centers to yield octahedral complexes with the metal in the +III oxidation state. These complexes are fully characterized by multinuclear NMR in solution and in the solid state. Preliminary density functional theory (DFT) calculations corroborate the preference for oxidative addition. Subsequently the study of performance thermoplastics which are important materials for the oil and gas industry is presented. The polymer morphology is studied by solid2state NMR techniques. Special attention is devoted to potential decomposition pathways at elevated temperatures for polyetheretherketone (PEEK) and polyphenylene sulfide (PPS) polymers. 13C CP/MAS (cross polarization with magic angle spinning) NMR and IR spectroscopy reveal that PEEK polymers show no detectable chemical change on the molecular level, while PPS polymers display signs of oxidation of the thioether group and branching via formation of ether, thioether, and biphenyl linkages. Furthermore, the water absorption of polybenzimidazole (PBI), polyetherketoneketone (PEKK), and their blend PEKK2PBI is studied. It is demonstrated that steam2treatment even at high temperatures and pressures does not cause chemical decomposition and that the changes, which are morphological in nature, are fully reversible.
25

Immobilized metallodithiolate ligand supports for construction of bioinorganic model complexes

Green, Kayla Nalynn 15 May 2009 (has links)
The A-cluster active site in acetyl coA synthase exploits a Ni(CGC)2- metallopeptide as a bidentate ligand to chelate the catalytically active square-planar nickel center used to produce acetyl coA. As Nature utilizes polypeptides to isolate and stabilize the active sites, we have set out to immobilize biomimetic complexes to polyethylene-glycol (PEG) rich polystyrene polymer beads (TentaGel). The PEG rich resin-beads serve to imitate the peptidic superstructure of enzyme active sites as well as to protect the resin-bound models from O2 decomposition. As a model of the NiN2S2 ligand observed in the A-cluster of acetyl coA synthase, the CGC tripeptide was constructed on resins using Merrifield solid phase peptide synthesis and then metallated with NiII to produce bright orange beads. Derivatization with M(CO)x (M = Rh, W) provided qualitative identification of Ο-Ni(CGC)M(CO)x n- via ATR-FTIR. Additionally, Neutron Activation Analysis (NAA) and UV-vis studies have determined the concentration of Ni and CGC, and qualitatively identify Ο-Ni(CGC)2-. Furthermore, infrared studies and NAA experiments have been used to identify and quantify Ο- Ni(CGC)Rh(CO)2 1-. The S-based reactivity of Ni(ema)2-, a good model of Ni(CGC)2-, toward oxygenation and alkylation has been pursued and compared to neutral NiN2S2 complexes. The spectroscopic, electrochemical and structural effects of these modifications will be discussed and supported using DFT computations and electrostatic potential maps of the resulting Ni(ema)*O2 2- and Ni(ema)*(CH2)3 complexes. Having firmly established the synthesis, characterization and reactivity of NiN2S2 2- systems in solution and resin-bound, CuIIN2S2 analogues were explored. The synthesis and identification of solution complexes, Cu(ema)2-, Cu(emi)2-, and Cu(CGC)2- via UV-Vis, EPR, and –ESI-MS will be discussed in addition to their S-based reactivity with Rh(CO)2 + . Furthermore, the resin-bound Cu(CGC)2- complex has been produced and characterized by EPR and its Rh(CO)2 adduct identified by ATR-FTIR and compared to the analogous NiN2S2 2- systems. As the active site of [FeFe] Hydrogenase utilizes a unique peptide-bound propane dithiolate bridge to support the FeFe organometallic unit, [FeFe]Hydrogenase models have been covalently anchored to the resin-beads via similar carboxylic acid functionalities. The characterization (ATR-FTIR, EPR, Neutron Activation Analysis), stability and reactivity of the immobilized models complexes are discussed as well as work toward establishing the microenvironment of resin-bound complexes.
26

Novel immobilization chemistry for bioaffinity sensors /

Yan, Fei. January 2001 (has links)
Thesis (Ph. D.)--State University of New York at Binghamton, Chemistry Department, 2001. / Includes bibliographical references (leaves 209-237).
27

Functional polymers and proteins at interfaces /

Schilke, Karl F. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 173-189). Also available on the World Wide Web.
28

An investigation of the impact of immobilisation on the activity of dihydrodipicolinate synthase : thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy at the University of Canterbury /

Baxter, Chris Logan. January 2007 (has links)
Thesis (Ph. D.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.
29

New micropatterning techniques for the spatial addressable immobilization of proteins

Filipponi, Luisa. January 2006 (has links)
Thesis (PhD) - Swinburne University of Technology, Industrial Research Institute Swinburne - 2006. / A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy, Industrial Research Institute Swinburne, Swinburne University of Technology - 2006. Typescript. Includes bibliographical references (p. 184-197).
30

Thermally reversible hydrogels for controlled drug delivery and enzyme immobilization /

Dong, Liang-Chang, January 1990 (has links)
Thesis (Ph. D.)--University of Washington, 1990. / Vita. Includes bibliographical references (leaves [210]-222).

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