Structural and kinetic studies of surfactant and phospholipid monolayers at the air/liquid interface using sum-frequency generation spectroscopy
type: CreativeWork
description: In this work, the non-linear optical technique of sum-frequency spectroscopy (SFG) has been used to investigate a variety of surfactant and phospholipid systems at different interfaces. Firstly, the effects of temperature and ionic strength on the adsorption of cationic and non-ionic surfactants were investigated. The binary surfactant system used here is a simplified hair conditioner model, consisting of a fatty alcohol and a long chain quaternary ammonium salt, self-assembled from solution onto a silica surface (which serves as a very approximate model of the hair surface). SFG was used to investigate and the effects of temperature and ionic strength on the conformational ordering of the adsorbed monolayer. The structure of a tethered bilayer lipid membrane (tBLM) produced by different methods was investigated. The tBLM is a bilayer of phospholipids, which are tethered to a gold substrate by a self-assembled monolayer (SAM). The SAM is a mixture of disulfide tether molecules and disulfide spacer molecules, which form covalent bonds to the gold surface. Ideally, the tether molecules should inter-digitate into the phospholipid membrane and hold it to the gold surface. This type of system is often used as a robust model for a cell membrane. Here, SFG was used to investigate the structure of the SAM, and of the membrane when formed either by rapid solvent exchange, or by a combination of Langmuir-Blodgett and Langmuir-Schaefer deposition. Significant differences in the resulting spectra of the tBLM were observed, as a result of the fabrication technique. SFG was also used to confirm that the polar orientation of the phospholipid in the tethered membrane systems was as expected for a bilayer. Two versions of the quaternary ammonium surfactant used previously were also investigated at the air/water interface. The only difference between the two surfactants was their counterion. The slow collapse of the compressed monolayer was monitored using SFG and by surface pressure…
abstract: In this work, the non-linear optical technique of sum-frequency spectroscopy (SFG) has been used to investigate a variety of surfactant and phospholipid systems at different interfaces. Firstly, the effects of temperature and ionic strength on the adsorption of cationic and non-ionic surfactants were investigated. The binary surfactant system used here is a simplified hair conditioner model, consisting of a fatty alcohol and a long chain quaternary ammonium salt, self-assembled from solution onto a silica surface (which serves as a very approximate model of the hair surface). SFG was used to investigate and the effects of temperature and ionic strength on the conformational ordering of the adsorbed monolayer. The structure of a tethered bilayer lipid membrane (tBLM) produced by different methods was investigated. The tBLM is a bilayer of phospholipids, which are tethered to a gold substrate by a self-assembled monolayer (SAM). The SAM is a mixture of disulfide tether molecules and disulfide spacer molecules, which form covalent bonds to the gold surface. Ideally, the tether molecules should inter-digitate into the phospholipid membrane and hold it to the gold surface. This type of system is often used as a robust model for a cell membrane. Here, SFG was used to investigate the structure of the SAM, and of the membrane when formed either by rapid solvent exchange, or by a combination of Langmuir-Blodgett and Langmuir-Schaefer deposition. Significant differences in the resulting spectra of the tBLM were observed, as a result of the fabrication technique. SFG was also used to confirm that the polar orientation of the phospholipid in the tethered membrane systems was as expected for a bilayer. Two versions of the quaternary ammonium surfactant used previously were also investigated at the air/water interface. The only difference between the two surfactants was their counterion. The slow collapse of the compressed monolayer was monitored using SFG and by surface pressure…
author: Goussous, Sami
language: en
keywords: Chemistry, Surfactant, Sum frequency spectroscopy, SFG, Langmuir monolayer, Surfactin, Phospholipid, Quaternary ammonium surfactants, quats, Langmuir-Blodgett, Spectroscopy, monolayer, cell membrane model, surfactin phospholipid interaction, phospholipid monolayer
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/a8742292-bac5-4e9e-92cf-2e19de4f31b1/download
license: https://creativecommons.org/licenses/by-nc/4.0/
date published: 2019-08-31
date modified: 2026-07-22T22:24:24Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.45743