Jump to main content
Jump to site search

Issue 47, 2017
Previous Article Next Article

Effects of ionic liquids on the nanoscopic dynamics and phase behaviour of a phosphatidylcholine membrane

Author affiliations

Abstract

Ionic liquids (ILs) are potential candidates for new antimicrobials due to their tunable antibacterial and antifungal properties that are required to keep pace with the growing challenge of bacterial resistance. To a great extent their antimicrobial actions are related to the interactions of ILs with cell membranes. Here, we report the effects of ILs on the nanoscopic dynamics and phase behaviour of a dimyristoylphosphatidylcholine (DMPC) membrane, a model cell membrane, as studied using neutron scattering techniques. Two prototypical imidazolium-based ILs 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM[BF4]) and 1-decyl-3-methylimidazolium tetrafluoroborate (DMIM[BF4]), which differ only in terms of the alkyl chain length of cations, have been used for the present study. Fixed Elastic Window Scan (FEWS) shows that the incorporation of ILs affects the phase behaviour of the phospholipid membrane significantly and the transition from a solid gel to a fluid phase shifts to lower temperature. This is found to be consistent with our differential scanning calorimetry measurements. DMIM[BF4], which has a longer alkyl chain cation, affects the phase behaviour more strongly in comparison to BMIM[BF4]. The pressure–area isotherms of the DMPC monolayer measured at the air–water interface show that in the presence of ILs, isotherms shift towards higher area-per lipid molecule. DMIM[BF4] is found to shift the isotherm to a greater extent compared to BMIM[BF4]. Quasielastic neutron scattering (QENS) data show that both ILs act as a plasticizer, which enhances the fluidity of the membrane. DMIM[BF4] is found to be a stronger plasticizing agent in comparison to BMIM[BF4] that has a cation with a shorter alkyl chain. The incorporation of DMIM[BF4] enhances not only the long range lateral motion but also the localised internal motion of the lipids. On the other hand, BMIM[BF4] acts weakly in comparison to DMIM[BF4] and mainly alters the localised internal motion of the lipids. Any subtle change in the dynamical properties of the membrane can profoundly affect the stability of the cell. Hence, the dominant effect of the IL with the longer chain length on the dynamics of the phospholipid membrane might be correlated with its cytotoxic activity. QENS data analysis has provided a quantitative description of the effects of the two imidazolium-based ILs on the dynamical and phase behaviour of the model cell membrane, which is essential for a detailed understanding of their action mechanism.

Graphical abstract: Effects of ionic liquids on the nanoscopic dynamics and phase behaviour of a phosphatidylcholine membrane

Back to tab navigation

Publication details

The article was received on 07 Sep 2017, accepted on 07 Nov 2017 and first published on 07 Nov 2017


Article type: Paper
DOI: 10.1039/C7SM01799E
Citation: Soft Matter, 2017,13, 8969-8979
  •   Request permissions

    Effects of ionic liquids on the nanoscopic dynamics and phase behaviour of a phosphatidylcholine membrane

    V. K. Sharma, S. K. Ghosh, P. Mandal, T. Yamada, K. Shibata, S. Mitra and R. Mukhopadhyay, Soft Matter, 2017, 13, 8969
    DOI: 10.1039/C7SM01799E

Search articles by author

Spotlight

Advertisements