DEVELOPMENT AND EVALUATION OF CONDUCTIVE NANOWIRESUSING DEOXYRIBONUCLEIC ACID AS A TEMPLATE

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dc.contributor.authorSIYAKA, MOMOH JIMOH ZUBAIRU
dc.date.accessioned2016-04-18T08:06:33Z
dc.date.available2016-04-18T08:06:33Z
dc.date.issued2015-07
dc.descriptionA THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLOUNIVERSITY, ZARIA INPARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF DOCTOR OF PHILOSOPHY IN INORGANIC CHEMISTRY DEPARTMENT OF CHEMISTRY FACULTY OF SCIENCE AHMADU BELLO UNIVERSITY, ZARIA, NIGERIAen_US
dc.description.abstractFeOOH, Fe2O3, polyimidazole (PImi) and polypyrrole (Ppy) were grown on λ-DNA as template strategy using bottom-up approach by the oxidation of the corresponding precursors into leaf-like and wire-like structures,respectively with diameters ranging between 6 and 30 nm. The bottom-up synthetic approach is based on the DNA π-stacking and base-pairing interaction with the precursor or the coordination of the donor site on the DNA nuleobases and phosphate group with the nanoparticles. These promote the growth of the templated materials into 1D nanostructured architecture by co-precipitation of iron oxide from their salt solutions and/or induce polymerisation with FeCl3. All the nanowires were synthesised in aqueous solution and aligned on oxidized silicon wafers by molecular combing method that relies on a combination of fluid flow and surface tension forces. Combination of microscopic and spectroscopic techniques for chemical family/identity, the structural character and electronic pathways showed that the nanowires considered comprised of crystallographic phases of the two iron oxide semiconductor nanoparticles,Ppy and PImi films bound to the template strands over time in a process analogous to Ostwald ripening. The TEM morphologies of the two iron oxides show parallel rough continuous leaf-like topography so elongate along the duplex DNA template axis to yield the dendritic morphology of the final nanowires, unlike the two DNA/templated polymers that displayed continuous beads-on-a-string chain-like arrays on the DNA phases. The AFM topographies translated the interaction into the directing ability of the template into high aspect ratio nanostructured materials with densely packed nanoparticles linearly arranged as nanowires. The diameter typically lies in the 6.5-33 nm for DNA/Ppy, 7.0-28 nm for DNA/Plmi, 5-27 nm for DNA/FeOOH and 3.0-26 nm for DNA/Fe2O3nanowires from statistical treatment of the nanowires size distributions. Analysis of the nanostructures reveals symmetrical distribution of the structure heights around the above modal values. Overall TEM xxvi morphology accounts for the phenomena observed in the AFM studies. Electronic probe of the nanowires by non-contact method via scanned conductance microscopy identifies DNA/FeOOH, DNA/Ppy and DNA/PImi to follow negative parabolic dependence,an indication of conductive characteristic. On the other hand, DNA/Fe2O3 was observed to follow positive parabolic dependence indicating non-conductive behaviour. These investigations demonstrate that duplex DNA-based nanowires with predictable and controllable shape, size, morphology and composition hold promise for downscaling and extension of Moore‟s law with application in gas sensorsfabrication and assessing (in vitro) cancer cells as target binding bio-diagnostic assays.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/7698
dc.language.isoenen_US
dc.subjectDEVELOPMENT,en_US
dc.subjectEVALUATION,en_US
dc.subjectEVALUATION,en_US
dc.subjectNANOWIRESUSING,en_US
dc.subjectDEOXYRIBONUCLEIC,en_US
dc.subjectACID,en_US
dc.subjectTEMPLATEen_US
dc.titleDEVELOPMENT AND EVALUATION OF CONDUCTIVE NANOWIRESUSING DEOXYRIBONUCLEIC ACID AS A TEMPLATEen_US
dc.typeThesisen_US
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