Paper Number
VP84
Session
Pre-recorded Flash Presentations (virtual)
Title
Interfacial rheology of phospholipid monolayers
Presentation Date and Time
All Week (Asynchronous) Any Time
Track / Room
Pre-recorded Presentation / Virtual
Authors
- Renggli, Damian (ETH Zurich, Materials)
- Vermant, Jan (ETH Zurich, Materials Departement)
Author and Affiliation Lines
Damian Renggli and Jan Vermant
Materials Departement, ETH Zurich, Zurich 8093, Switzerland
Speaker / Presenter
Renggli, Damian
Keywords
experimental methods; biological materials; interfacial rheology; rheology methods; surfactants
Text of Abstract
The membrane fluidity of phospholipid bilayers plays a central role in many biological processes, e.g. for cell homeostasis. Membranes not only compartmentalize the cytoplasm and various organelles, but they are also relevant for cell signaling where fine-tuning of the membrane fluidity is a necessity. The formation of metastatic cancer cells relies on an increase in membrane fluidity, which represents just one of many diseases related with membrane fluidity dysfunction. One approach to measure the investigate the mechanical properties of phospholipid bilayers is to investigate the interfacial rheology phospholipid monolayers—one leaflet of the lipid bilayer—under relevant conditions. Furthermore, monolayers have a relevance of their own as they coat the alveoli and prevent lung collapse. Therefore, phospholipids are used in pulmonary lung surfactant replacements for premature infants as well as for adults (acute respiratory distress syndrome). We investigate monolayers of various phospholipids at the water—air and buffer—oil interface, controlling temperature and surface pressure. Their linear viscoelastic regime is probed with oscillatory interfacial shear rheology by the interfacial needle stress rheometer (ISR), which is a macroscopic technique.[1] The lipid mixtures under investigation consist of phosphatidylcholines with saturated (palmitoyl) and unsaturated (oleoyl) fatty acids leading to different melting temperatures of the hydrophobic tails. At sufficiently high surface pressures, the saturated lipids pack efficiently and form liquid condensed phases leading to crowded membranes. The phases can undergo various shape instabilities depending on their size and balance of attractive and repulsive interactions between the lipids. The phase behavior is imaged simultaneously to the rheological measurement by a fluorescent microscope mounted on the ISR. [1] D. Renggli, A. Alicke, R. H. Ewoldt, and J. Vermant, J. Rheol., vol. 64, no. 1, pp. 141–160, Jan. 2020.