Using Vibrational Laser Spectroscopy to Study Biologically Relevant Interfaces
type: CreativeWork
description: In this thesis, the advanced spectroscopic techniques of atomic force microscopy - infrared (AFM-IR) spectroscopy and sum-frequency generation (SFG) spectroscopy are explored in detail for their innate ability to unravel the complexities of biological interfaces. The benefits of both techniques are demonstrated through applications to a variety of different interfaces, ranging from whole cells and aggregates (red blood cells and hair fibres) to artificial mimics (hydrogels) and thin molecular films (phospholipid monolayers). Specifically, the lateral chemical resolution and surface sensitivity of AFM-IR are used to chemically characterise the constituent components of biologically relevant systems below the diffraction limit whilst correlating these measurements to the nanoscale physical properties of the surface, such as topography, friction, and adhesion, that are accessible through traditional AFM. Similarly, the inherent surface specificity and sub-monolayer sensitivity of SFG is utilised, along with its ability to elucidate chemical structure and conformation, to probe oxidation in cell membranes, both in whole cells and monolayer mimics, thereby yielding a much deeper understanding of the oxidation mechanism due to reactive oxygen species (ROS) in physiological systems. Furthermore, some limitations and challenges associated with the use of these techniques in biologically relevant systems are identified, characterised and discussed, along with potential ways to circumvent them or minimise their impact in such investigations. Specifically, the inability of AFM-IR to probe thick substrates under aqueous conditions is discussed due to the relevance to studying many biological systems under physiological conditions. A novel method of sample preparation is proposed to maintain pseudo-aqueous conditions for the substrate whilst avoiding the limitations associated with AFM-IR measurement. Additionally, the common application of SFG to study surfactant monolayers at …
abstract: In this thesis, the advanced spectroscopic techniques of atomic force microscopy - infrared (AFM-IR) spectroscopy and sum-frequency generation (SFG) spectroscopy are explored in detail for their innate ability to unravel the complexities of biological interfaces. The benefits of both techniques are demonstrated through applications to a variety of different interfaces, ranging from whole cells and aggregates (red blood cells and hair fibres) to artificial mimics (hydrogels) and thin molecular films (phospholipid monolayers). Specifically, the lateral chemical resolution and surface sensitivity of AFM-IR are used to chemically characterise the constituent components of biologically relevant systems below the diffraction limit whilst correlating these measurements to the nanoscale physical properties of the surface, such as topography, friction, and adhesion, that are accessible through traditional AFM. Similarly, the inherent surface specificity and sub-monolayer sensitivity of SFG is utilised, along with its ability to elucidate chemical structure and conformation, to probe oxidation in cell membranes, both in whole cells and monolayer mimics, thereby yielding a much deeper understanding of the oxidation mechanism due to reactive oxygen species (ROS) in physiological systems. Furthermore, some limitations and challenges associated with the use of these techniques in biologically relevant systems are identified, characterised and discussed, along with potential ways to circumvent them or minimise their impact in such investigations. Specifically, the inability of AFM-IR to probe thick substrates under aqueous conditions is discussed due to the relevance to studying many biological systems under physiological conditions. A novel method of sample preparation is proposed to maintain pseudo-aqueous conditions for the substrate whilst avoiding the limitations associated with AFM-IR measurement. Additionally, the common application of SFG to study surfactant monolayers at …
author: Fellows, Alexander
language: eng
keywords: Biological Interfaces, Sum-Frequency Generation, AFM-IR, Infrared Nanospectroscopy, Surface Spectroscopy, Lipid Films, Red Blood Cells, Hair, Hydrogel, Oxidation, Reactive Oxygen Species
license: https://creativecommons.org/licenses/by/4.0/
date published: 2022-08-22
date modified: 2026-07-22T22:24:13Z
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.91194