| AVS 55th International Symposium & Exhibition | |
| Biomaterial Interfaces | Thursday Sessions |
| Session BI-ThP |
| Session: | Biomaterial Interfaces Poster Session with Focus on Engineered Bio-Interfaces and Sensors |
| Presenter: | M. Sundh, University of Aarhus, Denmark |
| Authors: | M. Sundh, University of Aarhus, Denmark S. Svedhem, Chalmers University of Technology, Sweden B. Kasemo, Chalmers University of Technology, Sweden D. Sutherland, University of Aarhus, Denmark |
| Correspondent: | Click to Email |
It is well known that artificial bilayers composed of ternary lipid mixtures of phosphatidylcholine, sphingomyelin (SM), and cholesterol (chol) phase separate and form domains enriched in SM and chol; so called rafts. Rafts are believed to be involved in numerous cellular processes such as cell signaling, endocytosis etc.1 and thus the importance of their study. Developments in the field of nanotechnology have opened up new routes to the study of molecular systems. The long term goal of these studies involves the use of nanostructured interfaces to systematically define parameters such as membrane curvature and allow the investigation of their correlation to phase separation. As a preliminary step the formation and quality of bilayers, formed with lipid raft compositions, on flat surfaces is investigated. Quartz crystal microbalance with dissipation (QCM-D) is a tool commonly used to study and quantify the adsorption of proteins and the fusion of lipid vesicles into lipid bilayers.2 In this study the influence of lipid composition in lipid vesicles on the formation of bilayers was investigated and interpreted in terms of the phase separation of the components. Ternary lipid mixtures of POPC/SM/chol at different ratios were formed into unilamellar vesicles by extrusion and deposited on SiO2 coated QCM crystals. Preliminary results show that the formation of lipid bilayers can be tuned by changing the lipid composition or temperature. An increase in the proportion of SM within the vesicles results in a reduction in quality of the formed bilayer, seen by an increased dissipation response. These results can be interpreted in terms of phase separation into ordered and disordered fluid domains within the vesicles. As the SM concentration is increased the ordered phase becomes dominant up to a point where the vesicles are too rigid to fuse and form bilayers. A temperature study of vesicles with POPC/chol shows that rupture of vesicles could be induced by doing the experiment at increased temperatures and hence changing the lipid phase.
1 Simons, K. and D. Toomre, Lipid rafts and signal transduction. Nat Rev Mol Cell Biol, 2000. 1(1): p. 31-39.
2 Reimhult, E., F. Hook, and B. Kasemo, Intact vesicle adsorption and supported biomembrane formation from vesicles in solution: Influence of surface chemistry, vesicle size, temperature, and osmotic pressure. Langmuir, 2003. 19(5): p. 1681-1691.