dc.contributor.advisor	Hafner, Jason H
dc.creator	Demers, Steven Meyer
dc.date.accessioned	2020-07-31T13:20:49Z
dc.date.available	2020-07-31T13:20:49Z
dc.date.created	2020-08
dc.date.issued	2020-07-29
dc.date.submitted	August 2020
dc.date.updated	2020-07-31T13:20:49Z
dc.description.abstract	Biological membranes are composed of numerous types of molecules ranging from different sterols to phospholipids to membrane partitioning proteins. While the overall compositions of these various elements are understood in part, how the phospholipid bilayer in cells accommodates the different processes for the copious types of proteins is not fully understood. Cholesterol however has been proven to play a key role in animal membrane functions. By using gold nanorods as a substrate, lipid membranes encapsulated the nanorods for the lipid structure to be analyzed by SERS. Optical excitation of gold nanoparticles at their size and shape-dependent plasmon resonant frequency induces strong oscillations of the nanoparticle’s free electron gas, leading to surfaced enhanced Raman scattering (SERS) – an enhancement of Raman scattering signals with a molecular scale distance dependence from the gold surface. The gold nanorods used for this project were tuned to an excitation laser wavelength of 785 nm. From previous lipid membrane studies, dioleoylphosphatidylcholine (DOPC) was demonstrated to have a well ordered, gold supported bilayer. Once a lipid bilayer was exchanged to the gold nanorod surface, a lipid solution interspersed with cholesterol was exchanged to the surface. The presence of cholesterol was confirmed in SERS by additional Raman peaks being observed that were characteristic of only cholesterol. Structural analysis by the surfaced enhanced Raman scattering (SABERS) method combines SERS and unenhanced Raman spectra with theoretical calculations of the optical field and molecular polarizability. Raman measurements of the samples are orientationally averaged while SERS spectra contain information on molecular position and orientation relative to the surface. Together these reveal the molecular orientation and position of cholesterol in phospholipid bilayers. This method offers an approach to analyzing lipid membrane molecular structure under ambient conditions, with microscopic quantities, and without molecular labels.
dc.format.mimetype	application/pdf
dc.identifier.citation	Demers, Steven Meyer. "Investigating Cholesterol Orientation in Lipid Bilayer by Raman Spectroscopy." (2020) Diss., Rice University. <a href="https://hdl.handle.net/1911/109123">https://hdl.handle.net/1911/109123</a>.
dc.identifier.uri	https://hdl.handle.net/1911/109123
dc.language.iso	eng
dc.rights	Copyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.
dc.subject	Biophysics
dc.subject	nanoscale
dc.subject	lipids
dc.subject	Raman
dc.subject	SERS
dc.subject	plasmonics
dc.title	Investigating Cholesterol Orientation in Lipid Bilayer by Raman Spectroscopy
dc.type	Thesis
dc.type.genre	Presentation
dc.type.material	Text
thesis.degree.department	Physics and Astronomy
thesis.degree.discipline	Natural Sciences
thesis.degree.grantor	Rice University
thesis.degree.level	Doctoral
thesis.degree.major	Biophysics
thesis.degree.name	Doctor of Philosophy

Investigating Cholesterol Orientation in Lipid Bilayer by Raman Spectroscopy

Files

Original bundle

License bundle

Collections