Supported Phospholipid Bilayer Interaction with Components Found in Typical Room-Temperature Ionic Liquids – a QCM-D and AFM Study

Abstract

Quartz crystal microbalance with dissipation (QCM-D) monitoring and atomic force microscopy (AFM) were combined to evaluate the defects created by an ionic liquid anion and a cation in a supported phospholipid bilayer composed of zwitterionic lipids on a silica surface. The cation 1-octyl-3-methyl imidazolium (OMIM + ) was shown to remove lipids from the bilayer, increase the roughness to approximately 2.8 nm (~0.2 for stable supported bilayer) and possibly redeposit lipids with entrapped water. The anion bis(trifluoromethylsulfonyl)imide (Tf 2 N -) was found to leave distinct defects within the bilayer that had large pore-like interiors which left the surrounding bilayer intact. However, the ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPTf 2 N) formed a film over the supported bilayer. This work demonstrates, for the first time, the direct effects common components of ionic liquids have on a supported phospholipids bilayer.

AFM study of the interaction of cytochrome P450 2C9 with phospholipid bilayers

“…Phase imaging was also employed to confirm the lamellar phases in the top leaflet, as the phase lag of the tip relative to the excitation signal is sensitive to surface properties, such as adhesion and viscoelasticity. Fig.2A (phase image) clearly demonstrates a large phase contrast (∼1 • ) between the two domains, which is interpreted as a change in bilayer softness (Evans, 2008;Leonenko et al, 2000), and thus confirms the proposed lamellar phases on the top leaflet of the DMPC bilayer.…”

Effect of pyrrolidinium based ionic liquid on the channel form of gramicidin in lipid vesicles

“…8, Panel B and C [61,62]. At CMC (100 mM) the size of the vesicles increases largely and the BMOP forms a film around the gramicidin vesicle, this type of behaviour of the pyrrolidinium based IL with vesicles has been reported earlier [23]. The above results signify that the membrane bound gramicidin in its channel form have strong interactions with BMOP and well supported by the above discussed results.…”

“…In depth investigation, computational as well as experimental studies of the interaction between ILs having different alkyl chain length and varied head groups with phospholipid membranes have been reported and the results showed disruption of the phospholipid bilayer at higher concentration of ILs with long hydrocarbon side chain [22][23][24]. Some recent findings also reported that ILs has the ability to fuse and aggregate lipid vesicles depending upon the length of the alkyl chain at higher concentrations [25,26].…”

Effects of imidazolium-based ionic surfactants on the size and dynamics of phosphatidylcholine bilayers with saturated and unsaturated chains

“…Evans showed that imidazolium-based ILs with longer hydrocarbon tails more significantly destabilize liposomes and supported lipid bilayers [21][22][23]. Jeong et al also showed that longer ILs at higher concentrations more effectively insert into membranes, which induces membrane instability, leading to the lower transition temperature of membranes [24].…”