Abstract
Fluorescence microscopy can be used to visualize coexisting fluid phases in lipid monolayers composed of cholesterol and dipalmitoyl phosphatidylcholine under specified conditions of temperature, composition, and lateral pressure. At a critical composition of ≈30 mol% cholesterol, decreasing the average molecular area below ac [unk]50 Å2 per molecule forces the binary mixture through a critical point, where the monolayer becomes homogeneous. At molecular areas ≈10% above this critical area, we observe shape transitions from liquid domains with circular shapes to domains with less symmetrical shapes. Shape transitions and critical shape fluctuations can also be triggered with light, due to photochemical effects on the monolayer. Shape fluctuations of lipid domains can thus be used to sense chemical events at the air-water interface.
Keywords: membranes, phase transitions, air-water interface, surface photochemistry
Full text
PDF
Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Ipsen J. H., Karlström G., Mouritsen O. G., Wennerström H., Zuckermann M. J. Phase equilibria in the phosphatidylcholine-cholesterol system. Biochim Biophys Acta. 1987 Nov 27;905(1):162–172. doi: 10.1016/0005-2736(87)90020-4. [DOI] [PubMed] [Google Scholar]
- McConnell H. M. Theory of hexagonal and stripe phases in monolayers. Proc Natl Acad Sci U S A. 1989 May;86(10):3452–3455. doi: 10.1073/pnas.86.10.3452. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Recktenwald D. J., McConnell H. M. Phase equilibria in binary mixtures of phosphatidylcholine and cholesterol. Biochemistry. 1981 Jul 21;20(15):4505–4510. doi: 10.1021/bi00518a042. [DOI] [PubMed] [Google Scholar]