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Submitted to: Annual Biophysical Meeting
Publication Type: Abstract Only Publication Acceptance Date: 2/23/2006 Publication Date: 2/23/2006 Citation: Evans, K.O. 2006. Supported phospholipid membrane interactions with 1-butyl-3-methyl imidazolium chloride, a room-temperature ionic liquid, on surfaces--a quartz crystal microbalance with dissipation study [abstract]. Proceedings of the Annual Biophysical Meeting. 2006 CD-ROM. p. B129. Interpretive Summary: Technical Abstract: The use of the quartz crystal microbalance with dissipation has made it relatively easy and straight-forward to monitor and study surface-supported phospholipid membranes as they interact with other molecules such as proteins and DNA on different surfaces. Here at the National Center of Agricultural Utilization Research we are interested in the formation of supported phospholipid membranes, what effects a self-assembled monolayer has on the formation process and whether a room-temperature ionic liquid (1-butyl-3-methyl imidazolium chloride, BMIM-Cl) disturbs the supported bilayer system. Earlier results have shown the following: 1) that vesicles composed solely of 1,2-dielaidoylphosphocholine (DEPC) adsorbed to silica until a critical concentration was achieved before forming a thin, single supported phospholipid bilayer; 2) that vesicles adsorbed mostly intact onto oxidized gold; and finally, 3) when the gold surface was made more hydrophilic with a self-assembled monolayer (SAM) of 11-mercapto-1-undecanoic acid and 11-mercatpoundecanol at 1:1 molar ratios, the phospholipid vesicles adsorbed intact with less mass, suggesting that less entrapped water was present (indicating a more flattened vesicle surface population). Current data will be present that shows that an addition of the anionic lipid 1,2-dimystiroylphosphocholine (DMPG) resulted in the following: 1) on silica, vesicles with DMPG present at less than 50 mole percent (2 – 20) also adsorbed to a critical concentration just prior to fusing and forming a single, thin supported bilayer; 2) on gold, the vesicles still adsorbed intact but at a slower rate with increased amount of DMPG; 3) on the SAM, as little as 2 mole percent of DMPG was needed to get the adsorbed vesicle to fuse to a single bilayer after a critical vesicular concentration was reached – however, more than 2% (5 – 50) resulted in slower adsorption of intact vesicles that did not fuse to form a thin, single bilayer; and 4) the addition of BMIM-Cl buffer did not disturb or disrupt the supported bilayer systems on any of these surface, except on the SAM when DMPG was present at 2 mole percent – some mass (lipids and/or water) was displaced. The importance of calcium ions will also be discussed. |
