| Cells are not at equilibrium; ion concentrations continuously fluctuate and molecules are transported, created, and destroyed leading to the dynamic environment necessary for life. Even the lipid composition of the cell membrane is known to vary throughout the lifetime of the cell; however, the effects of this variation on cellular function are generally unknown. Fluorescence recovery after photobleaching (FRAP), epi-fluorescence microscopy, confocal microscopy, and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) have been used to examine effect of lipid chemistries, heat, and ionic strength on the properties of supported lipid bilayers. It will be demonstrated that ATR-FTIR spectroscopy can be successfully used to obtain information about the conformation of lipid head groups (e.g. CN+C, PO 2-), the hydration/hydrogen-bonding between and around lipids (e.g. CO, PO2-), and the orientation/conformation of the hydrocarbon chains (e.g. CH2, CH3).; Results will also be presented demonstrating that it is possible to create both reversible and irreversible changes to the membrane organization and curvature through use of a biologically relevant process, fluctuations in the bulk ionic strength. Also demonstrated is the ability to control the fluidity of phase separation within a binary lipid mixture by alterations to the lipid compositions. |
