Adsorption and Self-assembly of Proteins at Chemically Modified Surfaces

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dc.contributor.advisorMorin, Sylvie
dc.creatorZahedijasbi, Shohreh
dc.date.accessioned2015-08-28T15:02:45Z
dc.date.available2015-08-28T15:02:45Z
dc.date.copyright2014-10-06
dc.date.issued2015-08-28
dc.date.updated2015-08-28T15:02:45Z
dc.degree.disciplineChemistry
dc.degree.levelDoctoral
dc.degree.namePhD - Doctor of Philosophy
dc.description.abstractOur research is mostly focused on the subject of adsorption and self-assembly of proteins at modified surfaces. We employed atomic force microscopy (AFM) to study bovine serum albumin (BSA) and insulin adsorption at 1-decene- and methyl 10-undecenoate-modified Si(111) substrates. The results were compared to matrix-assisted laser desorption/ionization-mass spectroscopy (MALDI-MS) data previously published in the Morin group. The MALDI-MS spectra showed a big insulin signal, while BSA was not detected for 1 mg/mL BSA and 10% saturated insulin solutions. Our AFM images revealed considerable BSA adsorption, whereas it was not possible to observe insulin molecules. This clearly shows that in addition to the low quantity of the protein, a stronger interaction between the surface and the protein may result in a weak MALDI-MS signal and prevent quantitative analysis using this technique. Self-assembled monolayers on Au surfaces were used to investigate the oligomerization of truncated K122-4 (ΔK122-4) pilins into a new protein nanostructure. Employing AFM, we observed that at hydrophobic layers, with more than 10-30% accessible hydrophobic component, ΔK122-4 pilins oligomerize to a nanoweb. To differentiate the structure of ΔK122-4 nanoweb from the aggregation of the pilins at hydrophilic surfaces, electrochemical impedance spectroscopy was employed. Through equivalent circuit fitting, capacitance values of 3.7 ± 0.4 μF/cm2 and 2.5 ± 0.2 μF/cm2 were obtained for the aggregated pilins and the web pattern, respectively. Because of the higher average thickness of the former layer, this could support the presence of water in this layer. A dielectric constant (ε) of 5.1 ± 0.7 was obtained for the nanoweb. This low value could indicate a more compact and ordered assembly. Finally, conductive protein nanotube (PNTs) fabrication was performed by electroless copper deposition at ΔK122-4 PNTs in aqueous solution. The nanostructures were catalyzed by PdCl42-. At least 20% of the accessible amino acids of the PNTs have S-, N- and O-donor side chains which are able to form a complex with Pd(II). Metallization was verified using scanning electron microscopy (SEM).
dc.identifier.urihttp://hdl.handle.net/10315/29921
dc.language.isoen
dc.rightsAuthor owns copyright, except where explicitly noted. Please contact the author directly with licensing requests.
dc.subjectChemistry
dc.subjectPhysical chemistry
dc.subjectAnalytical chemistry
dc.subject.keywordsProtein nanoweb
dc.subject.keywordsProtein nanotube
dc.subject.keywordsType IV pilin
dc.subject.keywordsΔK122-4
dc.subject.keywordsK122-4
dc.subject.keywordsPilin-based protein nanotube
dc.subject.keywordsPNT
dc.subject.keywordsNanostructure self-assembly
dc.subject.keywordsSurface oligomerization
dc.subject.keywordsSelf-assembled monolayer
dc.subject.keywordsMonolayer self-assembly
dc.subject.keywordsAlkanethiol self-assembled monolayer
dc.subject.keywordsAlkanethiol SAMs on gold
dc.subject.keywordsA(111)
dc.subject.keywordsNanostructure fabrication
dc.subject.keywordsScanning tunnelling microscope
dc.subject.keywordsElectrochemical impedance spectroscopy
dc.subject.keywordsEIS
dc.subject.keywordsEquivalent circuit
dc.subject.keywordsConductive bionanostructure
dc.subject.keywordsConductive nanostructure
dc.subject.keywordsNanotube metallization
dc.subject.keywordsCopper deposition
dc.subject.keywordsElectroless copper deposition
dc.subject.keywordsTransmission electron microscope
dc.subject.keywordsModified silicon
dc.subject.keywordsProtein
dc.subject.keywordsProtein adsorption
dc.subject.keywordsInsulin
dc.subject.keywordsBovine serum albumin
dc.subject.keywordsBSA
dc.subject.keywordsInsulin adsorption
dc.subject.keywordsBovine serum albumin adsorption
dc.subject.keywordsBSA adsorption
dc.subject.keywordsAtomic force microscope
dc.subject.keywordsAtomic force microscopy
dc.subject.keywordsAFM
dc.subject.keywordsSi(111)
dc.titleAdsorption and Self-assembly of Proteins at Chemically Modified Surfaces
dc.typeElectronic Thesis or Dissertationen_US

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