| Silica-Immobilized Enzymes for Multi-Step Synthesis in Microfluidic Devices (Postprint) |
OCT 2007 |
7 pages |
| Authors:
Heather R. Luckarift; Bosung S. Ku; Jonathan S. Dordick; Jim C. Spain; AIR FORCE RESEARCH LAB TYNDALL AFB FL MATERIALS AND MANUFACTURING DIRECTORATE
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 | The microfluidic combinatorial synthesis of 2-aminophenoxazin-3-one (APO) is reported. Individual microfluidic chips containing metallic zinc, silica-immobilized hydroxylaminobenzene mutase and silica-immobilized soybean peroxidase are connected in series to create a chem-enzymatic system for synthesis. Zinc catalyzes the initial reduction of nitrobenzene to hydroxylaminobenzene which undergoes a biocatalytic conversion to 2-aminophenol, followed by enzymatic polymerization to 2-aminophenoxazin-3-one. Silica-immobilization of enzymes allows the rapid stabilization and integration of a biocatalyst within a microfluidic ... |
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| Three Dimensional Immobilization of Beta-Galactosidase on a Silicon Surface (Preprint) |
DEC 2006 |
28 pages |
| Authors:
Heather R. Luckarift; Lorena Betancor; Jim C. Spain; GEORGIA INST OF TECH ATLANTA SCHOOL OF CIVIL ENGINEERING
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| Many alternative strategies to immobilize and stabilize enzymes have been investigated in recent years for applications in biosensors. The entrapment of enzymes within silica-based nanospheres formed through silicification reactions provides high loading capacities for enzyme immobilization, resulting in high volumetric activity and enhanced mechanical stability. Here we report a strategy for chemically-associating silica nanospheres containing entrapped enzyme to a silicon support. Beta-Galactosidase was used as a model enzyme due to ... |
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| Biosensor for Continuous Monitoring of Organophosphate Aerosols (Preprint) |
DEC 2006 |
22 pages |
| Authors:
Heather R. Luckarift; Glenn R. Johnson; Roby Greenwald; Mike Bergin; Jim C. Spain; APPLIED RESEARCH ASSOCIATES INC TYNDALL AFB FL
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| An enzyme-based monitoring system provides the basis for continuous sampling of organophosphate contamination in air. The enzymes butyrylcholinesterase (BuChE) and organophosphate hydrolase (OPH) are stabilized by encapsulation in biomimetic silica nanoparticles, entrained within a packed bed column. The resulting immobilized enzyme reactors (IMERS) were integrated with an impinger-based aerosol sampling system for collection of chemical contaminants in air. The sampling system was operated continuously and organophosphate detection was performed in ... |
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| Probing the Role of Promoters in Zinc Reduction of Nitrobenzene: Continuous Production of Hydroxylaminobenzene [PREPRINT] |
30 OCT 2006 |
24 pages |
| Authors:
Lixiong Li; Theodore V. Marolla; Lloyd Nadeau; Jim C. Spain; AIR FORCE RESEARCH LAB TYNDALL AFB FL MATERIALS AND MANUFACTURING DIRECTORATE
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| Production of hydroxylaminobenzene (HAB) via zinc reduction of nitrobenzene (NB) is an established batch process based on aqueous electrolytic reactions involving an electrolyte as the promoter. This experimental study explored continuous production of HAB that is needed as an intermediate in a novel zinc/biocatalyst processing train to obtain aminophenols. Experiments were conducted suing a Zn packed bed to probe the role of promoters under continuous-flow conditions at a temperature of ... |
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| Continuous-Flow Applications of Silica-Encapsulated Enzymes |
13 OCT 2006 |
12 pages |
| Authors:
Heather R. Luckarift; Glenn R. Johnson; Melanie M. Tomczak; Rajesh R. Naik; Jim C. Spain; AIR FORCE RESEARCH LAB TYNDALL AFB FL MATERIALS AND MANUFACTURING DIRECTORATE
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| Recent studies have demonstrated the applicability of biomineralization reactions to create an inorganic support matrix suitable to enzyme immobilization. The enzyme/inorganic nanocomposites exhibit excellent mechanical stability and provide an effective method for developing immobilized enzyme reactors, applicable to biocatalysis, biosensors and drug discovery. Enzymes are remarkably versatile catalysts, but in their native soluble form are often labile in the absence of stabilizing agents and are difficult to recover from reaction ... |
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| Coimmobilization of a Redox Enzyme and a Cofactor Regeneration System |
JUL 2006 |
4 pages |
| Authors:
Lorena Betancor; Cecile Berne; Heather R. Luckarift; Jim C. Spain; GEORGIA INST OF TECH ATLANTA SCHOOL OF CIVIL AND ENVIRONMENTAL ENGINEERING
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| The co-immobilization of nitrobenzene nitroreductase and glucose-6-phosphate dehydrogenase in silica particles enables the continuous conversion of nitrobenzene to hydroxylaminobenzene with NADPH recycling. |
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| Silica-Immobilized Enzyme Reactors; Application to Cholinesterase-Inhibition Studies |
MAR 2006 |
10 pages |
| Authors:
Heather R. Luckarift; Glenn R. Johnson; Jim C. Spain; GEORGIA INST OF TECH ATLANTA SCHOOL OF CIVIL AND ENVIRONMENTAL ENGINEERING
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| A rapid and economical method is reported for the preparation of an immobilized enzyme reactor (IMER) using silica-encapsulated equine butyrycholinestearse (BuChE) as a model system. Peptide-mediated silica formation was used to encapsulate BuChE, directly immobilizing the enzyme within a commercial pre-packed column. The silica/enzyme nanocomposites form and attach simultaneously to the metal affinity column via a histidine-tag on the silica-precipitating peptide. BuChE-IMER column were integrated to a liquid chromatography system ... |
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| Bacterial Degradation of DNT and TNT Mixtures |
31 OCT 2005 |
100 pages |
| Authors:
Rebecca E. Parales; Jim C. Spain; Glenn R. Johnson; CALIFORNIA UNIV DAVIS DEPT OF MICROBIOLOGY AND IMMUNOLOGY
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| The major objective of this research project was to develop bacterial strains with the ability to efficiently degrade mixtures of dinitrotoluene (DNT) isomers and expand that degradation capability to include TNT. Since most contaminated sites contain mixtures of nitroarene compounds, these strains would have the potential for use in the bioremediation of field sites. We have isolated strains that can degrade several nitroarene compounds, including nitrobenzene, 2-nitrotoluene (2NT) and 2,4- ... |
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| Entrapment of Enzymes and Nanoparticles Using Biomimetically Synthesized Silica |
07 JUL 2004 |
3 pages |
| Authors:
Rajesh R. Naik; Melanie M. Tomczak; Heather R. Luckarift; Jim C. Spain; Morley O. Stone; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| Entrapment of enzymes and nanoparticles using biosilification reactions. |
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| Evolution of Catabolic Pathways for Synthetic Compounds Bacterial Pathways for Degradation of 2,4-dinitrotoluene and Nitrobenzene |
15 MAY 2003 |
15 pages |
| Authors:
Glenn R. Johnson; Jim C. Spain; AIR FORCE RESEARCH LAB TYNDALL AFB FL MATERIALS AND MANUFACTURING DIRECTORATE
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| The pathways for 2,4-dinitrotoluene (2,4-DNT) and nitrobenzene offer fine illustrations of how the ability to assimilate new carbon sources evolves in bacteria. Studies of the degradation pathways provide insight about two principal strategies for overcoming the metabolic block imposed by nitro- substituents on aromatic compounds. The 2,4-DNT pathway uses novel oxygenases for oxidative denitration and subsequent ring-fission. The nitrobenzene pathway links facile reduction of the nitro-substituent, a novel mutase enzyme, ... |
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| Mechanism of Xanthine Oxidase Catalyzed Biotransformation of HMX Under Anaerobic Conditions |
2003 |
8 pages |
| Authors:
Bharat Bhushan; Louise Paquet; Annamaria Halasz; Jim C. Spain; Jalal Hawari; NATIONAL RESEARCH COUNCIL OF CANADA MONTREAL (QUEBEC) BIOTECHNOLOGY RESEARCH INST
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| Enzyme catalyzed biotransformation of the energetic chemical octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is not known. The present study describes a xanthine oxidase (XO) catalyzed biotransformation of HMX to provide insight into the biodegradation pathway of this energetic chemical. The rates of biotransformation under aerobic and anaerobic conditions were 1.6 0.2 and 10.5 0.9 nmol h 1 mg protein 1, respectively, indicating that anaerobic conditions favored the reaction. The biotransformation rate was about 6-fold ... |
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