Date of Award

2015

Document Type

Thesis

Degree Name

Bachelor of Science (B.S.) in Biochemistry and University Honors

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.

Persistent Identifier

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

Available for download on Sunday, May 22, 2022

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