Microfluidic Transport Studies on Lipid Vesicles
type: CreativeWork
description: The plasma membrane is the outermost layer of a cell and separates it from the extracellular environment. The membrane, as well as the proteins that are anchored in it, plays a crucial role in the uptake and efflux of molecules. Lipid bilayers are therefore an important object of research in many fields of science, such as biophysics, pharmacology and synthetic biology. In this thesis, we develop new microfluidic methods that allow us to study the laws that govern the transport processes through lipid bilayers. We use the novel microfluidic Octanol-Assisted Liposome Assembly (OLA) technique to obtain lipid vesicles which serve as model membrane for our studies. We perform a literature review, where we discuss OLA and other techniques to obtain liposomes in detail, before we provide a biophysical analysis of liposomes generated with OLA and compare them to vesicles obtained via traditional techniques. The biophysical analysis represents the first systematic evaluation of the properties of GUVs produced with the OLA technique to date. Using a fluorescence intensity assay, we show that OLA allows for the production of GUVs with binary lipid mixtures of DOPC-DOPG and DOPC-DOPE in the 1:3, 2:2 and 3:1 lipid ratio. GUVs with binary lipid mixtures of DOPG-DOPE are only stable in the 1:3 and 2:2 mixing ratio, but not in the 3:1 ratio. We attribute this behaviour to the high charge density of this mixture and the lipid polymorphism which makes it energetically unfavourable for certain lipid compositions to form lamellar structures. We furthermore investigate the lateral lipid diffusivity of DOPC and POPC vesicles produced with OLA using fluorescence recovery after photobleaching (FRAP) and compare it to that of vesicles obtained via the established electroformation technique. We find the lateral diffusion coefficients to be quantitatively similar and in the range of 1 μm²/s for the different lipid systems and techniques tested. Finally, using a dithionite bleaching assay, we…
abstract: The plasma membrane is the outermost layer of a cell and separates it from the extracellular environment. The membrane, as well as the proteins that are anchored in it, plays a crucial role in the uptake and efflux of molecules. Lipid bilayers are therefore an important object of research in many fields of science, such as biophysics, pharmacology and synthetic biology. In this thesis, we develop new microfluidic methods that allow us to study the laws that govern the transport processes through lipid bilayers. We use the novel microfluidic Octanol-Assisted Liposome Assembly (OLA) technique to obtain lipid vesicles which serve as model membrane for our studies. We perform a literature review, where we discuss OLA and other techniques to obtain liposomes in detail, before we provide a biophysical analysis of liposomes generated with OLA and compare them to vesicles obtained via traditional techniques. The biophysical analysis represents the first systematic evaluation of the properties of GUVs produced with the OLA technique to date. Using a fluorescence intensity assay, we show that OLA allows for the production of GUVs with binary lipid mixtures of DOPC-DOPG and DOPC-DOPE in the 1:3, 2:2 and 3:1 lipid ratio. GUVs with binary lipid mixtures of DOPG-DOPE are only stable in the 1:3 and 2:2 mixing ratio, but not in the 3:1 ratio. We attribute this behaviour to the high charge density of this mixture and the lipid polymorphism which makes it energetically unfavourable for certain lipid compositions to form lamellar structures. We furthermore investigate the lateral lipid diffusivity of DOPC and POPC vesicles produced with OLA using fluorescence recovery after photobleaching (FRAP) and compare it to that of vesicles obtained via the established electroformation technique. We find the lateral diffusion coefficients to be quantitatively similar and in the range of 1 μm²/s for the different lipid systems and techniques tested. Finally, using a dithionite bleaching assay, we…
author: Schaich, Michael
language: eng
keywords: Microfluidics, Lipid Membranes, Giant Unilamellar Vesicles, Membrane Transport
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/e6b26ff9-0c01-4fa5-8cf7-9f583111ae15/download
license: https://creativecommons.org/licenses/by-nc-sa/4.0/
date published: 2020-03-26
date modified: 2026-07-22T22:24:32Z
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.55444