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MATERIALS AND MODIFICATION OF ELECTRODES FOR THE DETECTION OF BIOLOGICAL MOLECULES
Wandstrat, Michelle Marie

2006, Doctor of Philosophy, Miami University, Chemistry.
Sol-gels have been utilized in many applications due to many desirable properties. A limitation of sol-gels is the gradual collapse of their structure with time. To address this problem, sol-gels were formed from tetramethoxysilane in the presence and absence of generation-zero poly(amidoamine) dendrimers (G0-PAMAM). To test the hypothesis that G0-PAMAM, which serves as a crosslinking agent, will stabilize the structure, the pore volume was monitored over a 52-week period. The premise was that the crosslinking will result in rapid densification. Nitrogen adsorption data stabilized after 25 weeks when G0-PAMAM was present. In its absence, the total pore volume continued to decrease over the entire period. Phospholipids (PLs) determination is important in the food and pharmaceutical industries. Methods were developed for the detection of a PL, phosphatidylcholine (PC). Electrochemical oxidation of PC, was accomplished at a 4-aminothiophenol (ATP)-modified gold electrode coated with a layer-by-layer assembly of electrochemical catalyst (dirhodium phosphomolybdic acid), a trapping agent for PC (a cyclophane, CP, derivative, 1,4-xylylene-1,4-phenylene-diacetate), and a spacer (generation-4 polyamidoamine dendrimer, PAMAM). The hypothesized process was verified by quartz crystal microbalance measurements which showed that Au | ATP | CP | PAMAM | CP trapped 1.5 ± 0.4 nmol / cm² of PC. The oxidation of PC at 0.16 V vs. Ag | AgCl yielded a current that varied linearly with concentration over the range 1 - 50 μM. Finally, an electrochemically assisted method for deposition of nm-scale films of porous silica was developed. In aqueous, un-buffered solution at a potential where H+ is generated in a tetraethylorthosilicate sol, nm-scale, insulating deposits of silica on electrodes are formed. Inclusion of beta-cyclodextrin in the sol provides conductivity, presumably by producing channels in the film. With the addition of a mediator, RhII, the electrochemical oxidation of PC is demonstrated; the process occurs without the passivation that otherwise precludes the voltammetric determination of PLs. Voltammetric current proportional to PC concentration in the range 1 -100 μM is achieved with this electrode.
James Cox (Advisor)
177 p.

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Wandstrat, M. (2006). MATERIALS AND MODIFICATION OF ELECTRODES FOR THE DETECTION OF BIOLOGICAL MOLECULES. (Electronic Thesis or Dissertation). Retrieved from https://etd.ohiolink.edu/

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Wandstrat, Michelle. "MATERIALS AND MODIFICATION OF ELECTRODES FOR THE DETECTION OF BIOLOGICAL MOLECULES." Electronic Thesis or Dissertation. Miami University, 2006. OhioLINK Electronic Theses and Dissertations Center. 19 Nov 2018.

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Wandstrat, Michelle "MATERIALS AND MODIFICATION OF ELECTRODES FOR THE DETECTION OF BIOLOGICAL MOLECULES." Electronic Thesis or Dissertation. Miami University, 2006. https://etd.ohiolink.edu/

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