Electrochemistry of Cytochrome c on Self-Assembled Phosphonic Acid Terminated Alkanethiols on Gold

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dc.contributor.advisor Tatyana I. Smirnova, Committee Member en_US
dc.contributor.advisor Edmond F. Bowden, Committee Chair en_US
dc.contributor.advisor Morteza G. Khaledi, Committee Member en_US
dc.contributor.author Quan, Lan Tu en_US
dc.date.accessioned 2010-04-02T18:04:31Z
dc.date.available 2010-04-02T18:04:31Z
dc.date.issued 2005-01-27 en_US
dc.identifier.other etd-10292004-100531 en_US
dc.identifier.uri http://www.lib.ncsu.edu/resolver/1840.16/1492
dc.description.abstract The synthesis of 10-mercaptodecanylphosphonic acid (C10PA) and self-assembly of C10PA on gold electrodes are reported. The electrochemical characterization of cytochrome c (cyt c) adsorption on the C10PA self-assembled monolayer (SAM) and on mixed hydroxyl(OH)/phosphonic acid (PA) terminated SAMs is also described, and a comparison is made to the pure carboxylic acid (COOH) SAM. On the pure C10PA SAM, no electroactivity for adsorbed cyt c was obtained. This lack of electroactivity could be due to a lack of adsorption resulting from hydrogen binding among the diprotic phosphonic acid groups, which could act to limit ionization needed for electrostatic cyt c binding at the interface. Alternatively, it could be that cyt c does bind strongly to this SAM, but becomes denatured or oriented in an unfavorable position for electron transfer to take place. On the other hand, cyt c electroactivity was obtained on the mixed OH/PA SAMs. In the mixed SAM, the OH terminated alkanethiol serves as a hydrophilic diluent, spacing out the phosphonic acid groups and thus limiting their ability to engage in mutual hydrogen bonding. Studies undertaken to examine the effects of OH alkanethiol chain length, the mole ratio of OH/PA, and self-assembly time yielded an optimal set of conditions for cyt c electroactivity, namely a 10:1 ratio C11OH/C10PA mixed SAM prepared with a 2 hour assembly time. Under those conditions, the redox properties of adsorbed cyt c were determined and compared with results for the widely studied COOH SAM. The formal potentials obtained for horse cyt c for both the C11OH/C10PA mixed SAM and the C10COOH pure SAM were approximately 230 mV vs NHE. The surface coverage for both types of monolayer were ~ 10 pmol/cm2. The electron transfer rate constants obtained were 17.7 s-1 and 12.7 s-1 for C11OH/C10PA mixed SAM and C10COOH pure SAM, respectively. Overall, the redox properties of cyt c on C11OH/C10PA mixed SAM were found to be similar to those obtained for a pure C10COOH SAM of comparable thickness. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject Mixed SAMs en_US
dc.subject 10-mercaptodecanylphosphonic en_US
dc.subject SAMs en_US
dc.title Electrochemistry of Cytochrome c on Self-Assembled Phosphonic Acid Terminated Alkanethiols on Gold en_US
dc.degree.name MS en_US
dc.degree.level thesis en_US
dc.degree.discipline Chemistry en_US


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