The Effect of Hydrophilic Ionic Liquids 1-Ethyl-3-Methylimidazolium Lactate and Choline Lactate on Lipid Vesicle Fusion

Abstract

Ionic liquids (ILs) are room-temperature molten salts that have applications in both physical sciences and more recently in the purification of proteins and lipids, gene transfection and sample preparation for electron microscopy (EM) studies. Transfection of genes into cells requires membrane fusion between the cell membrane and the transfection reagent, thus, ILs may be induce a membrane fusion event. To clarify the behavior of ILs with cell membranes the effect of ILs on model membranes, i.e., liposomes, were investigated. We used two standard ILs, 1-ethyl-3-methylimidazolium lactate ([EMI][Lac]) and choline lactate ([Ch][Lac]), and focused on whether these ILs can induce lipid vesicle fusion. Fluorescence resonance energy transfer and dynamic light scattering were employed to determine whether the ILs induced vesicle fusion. Vesicle solutions at low IL concentrations showed negligible fusion when compared with the controls in the absence of ILs. At concentrations of 30% (v/v), both types of ILs induced vesicle fusion up to 1.3 and 1.6 times the fluorescence intensity of the control in the presence of [Ch][Lac] and [EMI][Lac], respectively. This is the first demonstration that [EMI][Lac] and [Ch][Lac] induce vesicle fusion at high IL concentrations and this observation should have a significant influence on basic biophysical studies. Conversely, the ability to avoid vesicle fusion at low IL concentrations is clearly advantageous for EM studies of lipid samples and cells. This new information describing IL-lipid membrane interactions should impact EM observations examining cell morphology.

Amphiphilic ionic liquid induced fusion of phospholipid liposomes

“…37 increased further, relatively higher amount of dye leaks out in the fusion time period and hence, relatively higher saturation values are observed. These amphiphilic cations have been shown to induce fusion in egg-PC 24 and DOPC vesicles 23 previously. However, these studies did not comment on the leaky nature of membrane fusion or formation of fusion-holes.…”

“…Eri et al have shown fusion of DMPC+SM (3:1) liposomes under the influence of ionic liquids containing short chain amphiphilic 1-ethyl-3methylimidazolium cations. 23 In another study, Galletti et al have compared the impact of difference cationic head groups on fusion of egg-PC liposomes. 24 Apart from these two reports, ionic liquid induced membrane fusion remains unexplored.…”

Correlation between Ionic Liquid Cytotoxicity and Liposome–Ionic Liquid Interactions

“…Lipids, disengaged from the disrupted liposomes, have further been shown to aggregate with surface‐active imidazolium based ILs forming IL‐lipid micelles, as seen also with other surfactants . In addition, imidazolium‐ and cholinium‐based ILs with lactate anion and imidazolium, pyrrolidinium, and pyridinium based ILs have been shown to even induce liposome fusion.…”

Thermodynamic and Ultrasonic Properties of Ascorbic Acid in Aqueous Protic Ionic Liquid Solutions

“…The thermo-physical properties of ILs can be tuned by appropriate selection of cation and anion, as a result ILs can be made biocompatible and these are found to be very attractive in various analytical applications, particularly, in the fabrication of various modified electrodeswhichcan be used to extract chemicals or compounds (synthetic colors) from food samples. Reports are available [ 6 – 12 ]were ILs have been used for the extraction of Sudan and Para Red dyes from chilli powder employinghigh performance liquid chromatography (HPLC), thus showing potential application of ILs in food industries [ 10 – 11 , 13 – 15 ].…”