Date of Award

2015

Document Type

Thesis

Department

Chemistry

First Advisor

Marilyn R. Mackiewicz

Subjects

Membrane proteins -- Research, Amyloid beta-protein, Alzheimer's disease -- Etiology

DOI

10.15760/honors.154

Abstract

Lipid-coated AuNPs are prepared as cellular membrane mimics to study the protein- membrane interactions that play a role in neurodegeneration. PC and PC/Chol (1:1) lipid- coated AuNPs are used to monitor Aβ oligomer and monomer cellular membrane interactions. We used fluorescence anisotropy and TAMRA conjugated Aβ1-42 (TAMRA-Aβ1-42) to determine Aβ binding to lipid-coated AuNPs. An increase in the fluorescence anisotropy (r) of TAMRA-Aβ1-42 in the presence of the lipid-coated AuNPs indicate that the Aβ monomers bind to the membrane surface. Based on the change in r the binding affinity of Aβ to the AuNPs at pH 6.5 is higher than at pH 8 and was greater for Au-SO-PC-HT compared Au-SO-PC-Chol- HT. Dynamic light scattering (DLS) confirmed that Aβ1-42 monomers as well as oligomers bind to the lipid bilayers of the AuNPs as is evident by an increase in the hydrodynamic diameter (HD) of the lipid-coated AuNPs. When incubated with Aβ monomers, DLS show the greatest increase in the HD of Au-SO-PC-HT verses the Au-SO-PC-Chol-HT. When incubated with Aβ oligomers, DLS a greater increase in HD is observed at pH 6.5 compared to 8, demonstrating that Aβ binding is pH dependent. To investigate if Aβ binding to lipid-coated AuNPs cause significant disruption in membrane integrity cyanide etching studies were performed. UV-vis showed no shift in the surface plasmon resonance or change in optical density of lipid-coated AuNPs for either membrane type at pH 6.5 or 8.0 demonstrating that Aβ binding to the AuNP membranes does not lead to significant membrane disruption.

Comments

An undergraduate honors thesis submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in University Honors and Biochemistry

Persistent Identifier

http://archives.pdx.edu/ds/psu/15394

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