Enhanced Microscopic Dynamics of a Liver Lipid Membrane in the Presence of an Ionic Liquid.

Veerendra K Sharma,R Mukhopadhyay,Victoria García Sakai,Sajal K Ghosh

doi:10.3389/fchem.2020.577508

Abstract

Ionic liquids (ILs) are an important class of emerging compounds, owing to their widespread industrial applications in high-performance lubricants for food and cellulose processing, despite their toxicity to living organisms. It is believed that this toxicity is related to their actions on the cellular membrane. Hence, it is vital to understand the interaction of ILs with cell membranes. Here, we report on the effects of an imidazolium-based IL, 1-decyl-3-methylimidazolium tetrafluoroborate (DMIM[BF4]), on the microscopic dynamics of a membrane formed by liver extract lipid, using quasielastic neutron scattering (QENS). The presence of significant quasielastic broadening indicates that stochastic molecular motions of the lipids are active in the system. Two distinct molecular motions, (i) lateral motion of the lipid within the membrane leaflet and (ii) localized internal motions of the lipid, are found to contribute to the QENS broadening. While the lateral motion could be described assuming continuous diffusion, the internal motion is explained on the basis of localized translational diffusion. Incorporation of the IL into the liver lipid membrane is found to enhance the membrane dynamics by accelerating both lateral and internal motions of the lipids. This indicates that the IL induces disorder in the membrane and enhances the fluidity of lipids. This could be explained on the basis of its location in the lipid membrane. Results are compared with various other additives and we provide an indication of a possible correlation between the effects of guest molecules on the dynamics of the membrane and its location within the membrane.

Highlights

Ionic liquids (ILs) are a particular class of organic salts in which the ions are poorly coordinated, which results in low melting temperatures (Hayes et al, 2015; Egorova et al, 2017)
Our work showed that 1-decyl-3-methylimidazolium tetrafluoroborate [C10MIM]+[BF4] [or [DMIM][BF4]] has the highest toxicity toward liver cancerous cells, which we suggest is due to the modulation of the structure and dynamics of the liver membrane due to the incorporation of IL (Bakshi et al, 2020)
In a quasielastic neutron scattering experiment, the scattered intensity is proportional to the double scattering cross section, which gives the probability of scattered neutrons within the solid angle element d, about the direction and with an energy exchange of dE = Ef-Ei (Ef and Er are the final and initial energy of the neutron, respectively)

Summary

Introduction

Ionic liquids (ILs) are a particular class of organic salts in which the ions are poorly coordinated, which results in low melting temperatures (Hayes et al, 2015; Egorova et al, 2017). ILs are non-explosive, non-flammable and have good thermal stability and high ionic conductivity (Hayes et al, 2015; Egorova et al, 2017). These ILs have various widespread industrial applications, such as in high-performance lubricants, in chemical and polymer synthesis, in energy harvesting, and in food and cellulose processing (Plechkova and Seddon, 2008; Plechkova et al, 2009; Hayes et al, 2015; Egorova et al, 2017).

Methods

Results

Conclusion